MANUAL 1 COVER · Photo Acknowledgments page 7 USDA NRCS page 19 page 33 Fairfax County, VA page 38 USDA NRCS page 38 Eric Livingston page 39 Roger Bannerman page 39

Urban Subwatershed Restoration Manual Series

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Manual 1Manual 1Manual 1Manual 1Manual 1

Version 2.0

Photo Acknowledgments

page 7 USDA NRCSpage 19 www.metrokc.govpage 33 Fairfax County, VApage 38 USDA NRCSpage 38 Eric Livingstonpage 39 Roger Bannermanpage 39 http://in.water.usgs.gov/river/page 43 USDA NRCSpage 44 Ft. Worth Department of Environmental Managementpage 45 www.cabq.gov/solidwaste/greenwst.htmlpage 50 www.cityschools.com/walkergrant/fsts/aboutprogram.html

Urban Subwatershed Restoration Manual No. 1

AN INTEGRATED FRAMEWORK TORESTORE SMALL URBAN WATERSHEDS

Prepared by:

Tom SchuelerCenter for Watershed Protection

8390 Main Street, 2nd FloorEllicott City, MD 21043

www.cwp.orgwww.stormwatercenter.net

Prepared for:

Office of Water ManagementU.S. Environmental Protection Agency

Washington, D.C.

February 2005

Copyright ©2005 by the Center for Watershed Protection.Material may be quoted provided credit is given.

Printed in the United States of America on recycled paper.

Version 2.0

Urban Subwatershed Restoration Manual 1 i

Foreword

FFFFForewordorewordorewordorewordoreword

Urban watershed restoration has recentlyevolved into a growing and sophisticatedpractice. Two decades ago, the number ofwatershed restoration efforts could be countedon one hand; now they number in the hundreds,with many more starting each year. With eachnew effort, more experience is gained, and thepractice of restoring urban watershedsbecomes ever more sophisticated and effective.We have learned many lessons so far: thatrestoration is technically challenging, takesmany years to complete, and requires broadpartnerships to build the dozens or evenhundreds of restoration practices needed for asmall watershed. While urban watershedrestoration is extremely challenging, it is alsoexceptionally rewarding to make a realdifference in the quality of our home waters.

This manual series was written for a broadaudience with an interest in the methods andtechniques to restore small urban watersheds,including planners, engineers, agency staff,watershed groups, and environmentalconsultants. The manuals distill our experienceacquired in many different watershedrestoration settings over the past two decadesinto a single package. During this time, we havesought to continuously refine, test and expandboth our restoration practices and oursubwatershed assessment tools. We expectedthat it would be further adjusted over time;therefore, we are pleased to release this manualin Version 2.0, in response to user feedback andnew resources. We sincerely hope that these

manuals will help guide your efforts tosuccessfully restore urban watersheds in yourcommunity.

Many thanks are extended to three externalreviewers who carefully looked over drafts ofthis manuscript. They include Derek Booth,University of Washington Center for Water andWatershed Research; Bill Stack, City ofBaltimore Department of Public Works; andThomas Davenport, national nonpoint sourceexpert for the U.S. Environmental ProtectionAgency. Much of this material was firstpresented at our inaugural WatershedRestoration Institute in September 2003, andthe common sense feedback from instituteparticipants is also keenly appreciated.

Many Center staff contributed to thedevelopment of this manual, including TedBrown, Anne Kitchell, Chris Swann, KarenCappiella, Hye Yeong Kwon, Jennifer Zielinski,and Stephanie Sprinkle. The hard work, diligentresearch and practical insights of thisoutstanding team is reflected throughout themanual. In addition, Tiffany Wright, HeatherHolland and Lauren Lasher cannot be thankedenough for their able assistance in editing,proofing and producing this manual. Finally, wewould like to acknowledge the patience, insightsand flexibility of our EPA project officer, RobertGoo, during the two years it took to producethis manual series under a cooperativeagreement with US EPA Office of Water CP-82981501.

Sincerely,

Tom SchuelerDirector of Watershed Research and PracticeCenter for Watershed Protection

Urban Subwatershed Restoration Manual 1ii

Foreword

Urban Subwatershed Restoration Manual 1 iii

Foreword

This is the first manual in an 11 manual seriesthat provides detailed guidance on how to repairurban watersheds. The entire series of manualswas written by the Center for WatershedProtection to organize the enormous amount ofinformation needed to restore small urbanwatersheds into a format that can easily beaccessed by watershed groups, municipal staff,environmental consultants and other users. Thecontents of the manuals are organized asfollows.

Manual 1: An IntegratedManual 1: An IntegratedManual 1: An IntegratedManual 1: An IntegratedManual 1: An IntegratedApproach to Restore SmallApproach to Restore SmallApproach to Restore SmallApproach to Restore SmallApproach to Restore SmallUrban WUrban WUrban WUrban WUrban Watershedsatershedsatershedsatershedsatersheds

The first manual introduces the basic conceptsand techniques of urban watershed restoration,and sets forth the overall framework we use toevaluate subwatershed restoration potential. Themanual emphasizes how past subwatershedalterations must be understood in order to setrealistic expectations for future restoration.Toward this end, the manual presents a simplesubwatershed classification system to defineexpected stream impacts and restorationpotential. Next, the manual defines seven broadgroups of restoration practices, and describeswhere to look in the subwatershed to implementthem. The manual concludes by presenting acondensed summary of a planning approach tocraft effective subwatershed restoration plans.

Manual 2: Methods toManual 2: Methods toManual 2: Methods toManual 2: Methods toManual 2: Methods toDevelop Restoration PlansDevelop Restoration PlansDevelop Restoration PlansDevelop Restoration PlansDevelop Restoration Plansfor Small Urban Wfor Small Urban Wfor Small Urban Wfor Small Urban Wfor Small Urban Watershedsatershedsatershedsatershedsatersheds

The second manual contains detailed guidanceon how to put together an effective plan torestore urban subwatersheds. The manualoutlines a practical, step-by-step approach todevelop, adopt and implement a subwatershedplan in your community. Within each step, the

manual describes 32 different desktop analysis,field assessment, and stakeholder involvementmethods used to make critical restorationmanagement decisions.

The next seven manuals provide specificguidance on how to identify, design, andconstruct the seven major groups of watershedrestoration practices. Each of these “practice”manuals describes the range of techniques usedto implement each practice, and providesdetailed guidance on subwatershed assessmentmethods to find, evaluate and rank candidatesites. In addition, each manual providesextensive references and links to other usefulresources and websites to design betterrestoration practices. The seven manuals areorganized as follows:

Manual 3: Storm WManual 3: Storm WManual 3: Storm WManual 3: Storm WManual 3: Storm WaterateraterateraterRetrofit PracticesRetrofit PracticesRetrofit PracticesRetrofit PracticesRetrofit Practices

The third manual focuses on storm waterretrofit practices that can capture and treatstorm water runoff before it is delivered to thestream. The manual describes both off-sitestorage and on-site retrofit techniques that canbe used to remove storm water pollutants,minimize channel erosion, and help restorestream hydrology. The manual then presentsguidance on how to assess retrofit potential atthe subwatershed level, including methods toconduct a retrofit inventory, assess candidatesites, screen for priority projects, and evaluatetheir expected cumulative benefit. The manualconcludes by offering tips on retrofit design,permitting, construction, and maintenanceconsiderations in a series of 17 retrofit profilesheets.

About the RAbout the RAbout the RAbout the RAbout the Restoration Manual Seriesestoration Manual Seriesestoration Manual Seriesestoration Manual Seriesestoration Manual Series

Urban Subwatershed Restoration Manual 1iv

Foreword

Manual 4: Urban StreamManual 4: Urban StreamManual 4: Urban StreamManual 4: Urban StreamManual 4: Urban StreamRepair PracticesRepair PracticesRepair PracticesRepair PracticesRepair Practices

The fourth manual concentrates on practicesused to enhance the appearance, stability,structure, or function of urban streams. Themanual offers guidance on three broadapproaches to urban stream repair – streamcleanups, simple repairs, and more sophisticatedcomprehensive repair applications. The manualemphasizes the powerful and relentless forcesat work in urban streams, which must alwaysbe carefully evaluated in design. Next, themanual presents guidance on how to setappropriate restoration goals for your stream,and how to choose the best combination ofstream repair practices to meet them.

The manual also outlines methods to assessstream repair potential at the subwatershedlevel, including basic stream reach analysis,more detailed project investigations, and priorityscreenings. The manual concludes by offeringpractical advice to help design, permit,construct and maintain stream repair practicesin a series of more than 30 profile sheets.

Manual 5: RiparianManual 5: RiparianManual 5: RiparianManual 5: RiparianManual 5: RiparianManagement PracticesManagement PracticesManagement PracticesManagement PracticesManagement Practices

The fifth manual examines practices to restorethe quality of forests and wetlands within theremaining stream corridor and/or flood plain. Itbegins by describing site preparation techniquesthat may be needed to make a site suitable forplanting, and then profiles four plantingtechniques for the riparian zone, based on itsintended management use. The manualpresents several methods to assess riparianrestoration potential at the subwatershed level,including basic stream corridor analysis,detailed site investigations, and screeningfactors to choose priority reforestation projects.The manual concludes by reviewing effectivesite preparation and planting techniques in aseries of eight riparian management profilesheets.

Manual 6: DischargeManual 6: DischargeManual 6: DischargeManual 6: DischargeManual 6: DischargePrevention PracticesPrevention PracticesPrevention PracticesPrevention PracticesPrevention Practices

The sixth manual covers practices used toprevent the entry of sewage and other pollutantdischarges into the stream from pipes and spills.The manual describes a variety of techniques tofind, fix and prevent these discharges that canbe caused by illicit sewage connections, illicitbusiness connections, failing sewage lines, orindustrial/transport spills. The manual alsobriefly presents desktop and field methods toassess the severity of illicit discharge problemsin your subwatershed. Lastly, the manualprofiles different “forensic” methods to detectand fix illicit discharges. Manual 6 is alsoknown as the Illicit Discharge Detection andElimination Guidance Manual: a guidancemanual for program development andtechnical assessment, and is referenced asBrown et al., 2004, throughout this manual.

Manual 7: WManual 7: WManual 7: WManual 7: WManual 7: Watershed Fatershed Fatershed Fatershed Fatershed ForestrorestrorestrorestrorestryyyyyPracticesPracticesPracticesPracticesPractices

The seventh manual reviews subwatershedpractices that can improve the quality of uplandpervious areas, which include techniques toreclaim land, revegetate upland areas, andrestore natural area remnants. When broadlyapplied, these techniques can improve thecapacity of these lands to absorb rainfall andsustain healthy plant growth and cover. Thisbrief manual also outlines methods to assess thepotential for these techniques at both the siteand subwatershed scale.

Manual 8: PManual 8: PManual 8: PManual 8: PManual 8: Pollution Sourceollution Sourceollution Sourceollution Sourceollution SourceControl PracticesControl PracticesControl PracticesControl PracticesControl Practices

Pollution source control practices reduce orprevent pollution from residential neighborhoodsor storm water hotspots. Thus, the topic of theeighth manual is a wide range of stewardshipand pollution prevention practices that can beemployed in subwatersheds. The manualpresents several methods to assess

Urban Subwatershed Restoration Manual 1 v

Foreword

subwatershed pollution sources in order todevelop and target education and/orenforcement efforts that can prevent or reducepolluting behaviors and operations. The manualoutlines more than 100 different “carrot” and“stick” options that can be used for thispurpose. Lastly, the manual presents profilesheets that describe 21 specific stewardshippractices for residential neighborhoods, and 15pollution prevention techniques for control ofstorm water hotspots.

Manual 9: MunicipalManual 9: MunicipalManual 9: MunicipalManual 9: MunicipalManual 9: MunicipalPractices and ProgramsPractices and ProgramsPractices and ProgramsPractices and ProgramsPractices and Programs

The ninth manual focuses on municipalprograms that can directly supportsubwatershed restoration efforts. The fivebroad areas include improved street and stormdrain maintenance practices, development/redevelopment standards, stewardship of publicland, delivery of municipal stewardshipservices, and watershed education andenforcement. This last “practice” manualpresents guidance on how municipalities canuse these five programs to promotesubwatershed restoration goals. The manualalso contains a series of profile sheets thatrecommends specific techniques to implementeffective municipal programs.

The series concludes with two user manualsthat explain how to perform field assessmentsto discover subwatershed restoration potentialin the stream corridor and upland areas.

Manual 10: The UnifiedManual 10: The UnifiedManual 10: The UnifiedManual 10: The UnifiedManual 10: The UnifiedStream Assessment (USA): AStream Assessment (USA): AStream Assessment (USA): AStream Assessment (USA): AStream Assessment (USA): AUserUserUserUserUser ’s Manual’s Manual’s Manual’s Manual’s Manual

The Unified Stream Assessment (USA) is arapid technique to locate and evaluate problemsand restoration opportunities within the urbanstream corridor. The tenth manual is a user’sguide that describes how to perform the USA,and interpret the data collected to determine thestream corridor restoration potential for yoursubwatershed.

Manual 11: The UnifiedManual 11: The UnifiedManual 11: The UnifiedManual 11: The UnifiedManual 11: The UnifiedSubwatershed and SiteSubwatershed and SiteSubwatershed and SiteSubwatershed and SiteSubwatershed and SiteReconnaissance (USSR): AReconnaissance (USSR): AReconnaissance (USSR): AReconnaissance (USSR): AReconnaissance (USSR): AUserUserUserUserUser ’s Manual’s Manual’s Manual’s Manual’s Manual

The last manual examines pollution sources andrestoration potential within upland areas ofurban subwatersheds. The manual providesdetailed guidance on how to perform each of itsfour components: the Neighborhood SourceAssessment (NSA), Hotspot Site Investigation(HSI), Pervious Area Assessment (PAA) andthe analysis of Streets and Storm Drains(SSD). Together, these rapid surveys helpidentify upland restoration projects and sourcecontrol to consider when devising subwatershedrestoration plans.

Individual manuals in the series are scheduledfor completion by 2006, and can be downloadedor delivered in hard copy for a nominal charge.Be sure to check the Center website,www.cwp.org, to find out when each manualwill be available and how it can be accessed.

Urban Subwatershed Restoration Manual 1vi

Foreword

Urban Subwatershed Restoration Manual 1 vii

Table of Contents

TTTTTable of Contentsable of Contentsable of Contentsable of Contentsable of Contents

Foreword .................................................................................................................................... i

About the Restoration Manual Series ........................................................................................ iii

Table of Contents ..................................................................................................................... vii

Introduction ............................................................................................................................... 1

Chapter 1: Organizing to RChapter 1: Organizing to RChapter 1: Organizing to RChapter 1: Organizing to RChapter 1: Organizing to Restore Urban Westore Urban Westore Urban Westore Urban Westore Urban Watershedsatershedsatershedsatershedsatersheds .................................................................................................................................................................................................................................................................................................................3

1.1 Getting the Terminology Right ............................................................................... 31.2 Trends Driving Growth in Urban Watershed Restoration ......................................... 41.3 Many Different Goals Guide Urban Watershed Restoration .................................. 61.4 The Role of Stakeholders in Watershed Restoration ............................................... 81.5 Organizing Stakeholders Into Action ................................................................... 13

Chapter 2: The Alteration of Urban SubwatershedsChapter 2: The Alteration of Urban SubwatershedsChapter 2: The Alteration of Urban SubwatershedsChapter 2: The Alteration of Urban SubwatershedsChapter 2: The Alteration of Urban Subwatersheds ...................................................................................................................................................................................................................................................................................................................... 15

2.1 Conversion to Impervious Cover ........................................................................ 152.2 Construction of Sewer, Water, and Storm Water Infrastructure ............................. 172.3 Intensive Management of Pervious Areas ........................................................... 172.4 Fragmentation of Natural Area Remnants ........................................................... 182.5 Interruption of the Stream Corridor ...................................................................... 182.6 Encroachment and Expansion in the Flood Plain................................................ 192.7 Increased Population Density .............................................................................. 202.8 Increased Density of Storm Water Hotspots ......................................................... 20

Chapter 3: Impacts of Urbanization on StreamsChapter 3: Impacts of Urbanization on StreamsChapter 3: Impacts of Urbanization on StreamsChapter 3: Impacts of Urbanization on StreamsChapter 3: Impacts of Urbanization on Streams .......................................................................................................................................................................................................................................................................................................................................... 21

3.1 Changes to Stream Hydrology ............................................................................ 233.2 Physical Alteration of the Stream Corridor ........................................................... 253.3 Degradation of Stream Habitat ........................................................................... 273.4 Decline in Water Quality ...................................................................................... 293.5 Loss of Aquatic Diversity ....................................................................................... 323.6 Summary ............................................................................................................. 35

Chapter 4: The RChapter 4: The RChapter 4: The RChapter 4: The RChapter 4: The Range of Subwatershed Range of Subwatershed Range of Subwatershed Range of Subwatershed Range of Subwatershed Restoration Pestoration Pestoration Pestoration Pestoration Practicesracticesracticesracticesractices ............................................................................................................................................................................................................................ 37

4.1 Storm Water Retrofit Practices .............................................................................. 374.2 Stream Repair Practices ....................................................................................... 394.3 Riparian Management Practices .......................................................................... 414.4 Discharge Prevention Practices ............................................................................ 444.5 Watershed Forestry Practices ............................................................................... 454.6 Pollution Source Control Practices........................................................................ 464.7 Municipal Practices and Programs ....................................................................... 494.8 Choosing the Right Combination of Restoration Practices for a Subwatershed ............................................................................................. 50

Urban Subwatershed Restoration Manual 1viii

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Chapter 5: Envisioning RestorationChapter 5: Envisioning RestorationChapter 5: Envisioning RestorationChapter 5: Envisioning RestorationChapter 5: Envisioning Restoration ..................................................................................................................................................................................................................................................................................................................................................................................................................... 55

5.1 The Remnant Stream Corridor ............................................................................. 555.2 Existing Storm Water Infrastructure ....................................................................... 565.3 Open Municipal Land ......................................................................................... 575.4 Natural Area Remnants ....................................................................................... 575.5 Road Crossings and Highway Rights-of-Way ....................................................... 575.6 Large Parking Lots ................................................................................................ 585.7 Storm Water Hotspots ........................................................................................... 605.8 Residential Neighborhoods ................................................................................. 605.9 Large Institutional Land Owners ........................................................................... 605.10 The Sewer System ............................................................................................... 625.11 Streets and Storm Drain Inlets ............................................................................. 625.12 Summary ............................................................................................................ 62

Chapter 6: A FChapter 6: A FChapter 6: A FChapter 6: A FChapter 6: A Framework for Small Wramework for Small Wramework for Small Wramework for Small Wramework for Small Watershed Ratershed Ratershed Ratershed Ratershed Restorationestorationestorationestorationestoration .......................................................................................................................................................................................................................................................... 65

Step 1: Develop Watershed Restoration Goals ........................................................... 67Step 2: Screen for Priority Subwatersheds ................................................................... 68Step 3: Evaluate Restoration Potential ........................................................................ 69Step 4: Conduct Detailed Restoration Assessment ..................................................... 70Step 5: Assemble Projects into Plan ............................................................................ 71Step 6: Determine Whether Subwatershed Plan Meets Watershed Goals .................. 72Step 7: Implement Plan .............................................................................................. 73Step 8: Measure Improvements Over Time ................................................................. 74Summary..................................................................................................................... 75

Appendix A: Derivation of Predictions for the Impervious Cover Model ............................... A-1

Appendix B: Organization of Restoration Technique Profile Sheetsfor the Manual Series ................................................................................................. B-1

References ............................................................................................................................. R-1

List of TList of TList of TList of TList of Tablesablesablesablesables

1. Selected Results of National Survey of Municipal Watershed Restoration Activity ........ 62. Hydrologic Predictions According to the ICM ............................................................... 253. ICM Predictions Concerning Physical Alteration of the Urban Stream Corridor ............ 264. Stream Habitat Predictions According to the ICM ......................................................... 285. Water Quality Predictions According to the ICM ........................................................... 306. Predictions on Aquatic Diversity According to the ICM ................................................. 347. Eleven Places to Envision Restoration in a Subwatershed ............................................. 55

List of FiguresList of FiguresList of FiguresList of FiguresList of Figures

1. The Stream Corridor and Upland Areas in Urban Subwatersheds ...................................... 42. General Classification of Watershed Restoration Goals ................................................... 73. Four Types of Stakeholders Involved in Watershed Restoration Plans ................................ 94. The Agency Stakeholder Pyramid .................................................................................... 95. The Public Stakeholder Pyramid ...................................................................................... 116. The Partner Stakeholder Pyramid ..................................................................................... 117. The Funder Stakeholder Pyramid ..................................................................................... 128. Six Urban Subwatersheds With Progressively Greater Impervious Cover ........................... 16

Urban Subwatershed Restoration Manual 1 ix

Table of Contents

9. Distribution of Natural Area Remnants in a Non-Supporting Subwatershed ....................... 1810. Stream Interruption in a Non-Supporting Subwatershed ................................................ 1911. Five Groups of Stream Impacts Associated with Urban Subwatersheds ......................... 2212. Representation of the Impervious Cover Model (ICM) ................................................... 2313. Comparison of Urban and Rural Hydrographs ............................................................... 2414. Loss of Riparian Forest Continuity in an Impacted Subwatershed.................................. 2615. Contrast in Habitat Features Between Rural and Non-Supporting Streams .................... 2816. Ten Major Categories of Pollutants Found in Urban Storm Water Runoff ........................ 2917. Relationship Between Subwatershed IC and Aquatic Insect Diversity ........................... 3318. Seven Groups of Practices Used to Restore Urban Watersheds ..................................... 3819. Example of a Storage Retrofit Pond ............................................................................... 3920. The Seven Basic Types of Stream Repair Techniques .................................................... 4021. Example of Comprehensive Stream Restoration Approach .......................................... 4222. Four Strategies to Establish Vegetation in the Riparian Area ......................................... 4323. Pollution Source Control Opportunities in Residential Neighborhoods.......................... 4724. Investigating Potential Storm Water Hotpots .................................................................. 4825. General Feasibility of Retrofit Practices at Different Levels of Subwatershed IC ........... 5126. General Ability to Meet Subwatershed Goals at

Different Levels of Subwatershed IC ............................................................................... 5327. Envisioning Restoration in the Remnant Stream Corridor ............................................... 5628. Envisioning Restoration Within Existing Storm Water Infrastructure ................................. 5729. Envisioning Restoration on Open Municipal Lands........................................................ 5830. Envisioning Restoration in Natural Area Remnants ........................................................ 5931. Envisioning Restoration at Road Crossings and Rights-of-Way ...................................... 5932. Envisioning Restoration in Large Parking Lots ................................................................. 6033. Envisioning Restoration for Storm Water Hotspots ........................................................... 6134. Envisioning Restoration in Residential Neighborhoods .................................................. 6135. Envisioning Restoration on Large Parcels of Institutional Land ...................................... 6136. Envisioning Restoration in the Sewer System .................................................................. 6237. Envisioning Restoration on Streets and Storm Drain Inlets .............................................. 6338. Overview of the Eight-Step Framework to Restore Urban Watersheds ........................... 6539. Detailed Steps and Tasks Involved in the Restoration Planning Process ....................... 66

List of Acronyms and AbbreviationsList of Acronyms and AbbreviationsList of Acronyms and AbbreviationsList of Acronyms and AbbreviationsList of Acronyms and AbbreviationsThe following list describes the many acronyms and abbreviations used in the manual todescribed the methods, practices, models used to restore small urban watersheds.

AFP: Adopt Final PlanASP: Adopt Subwatershed PlanASC: Achieving Stakeholder ConsensusB-IBI: Benthic Index of Biotic IntegrityCPI: Candidate Project InvestigationCRP: Create Restoration PartnershipsCSA: Comparative Subwatershed AnalysisCSO: Combined Sewer OverflowDDT: Dichloro-Diphenyl-TrichloroethaneDPI: Discharge Prevention InvestigationDSA: Detailed Subwatershed AnalysisDSP: Draft Subwatershed PlanEDA: Existing Data AnalysisEMC: Event Mean ConcentrationEPR: External Plan ReviewEPA: Environmental Protection AgencyEPT: Macroinvertebrate index that examines sensitive aquatic insect speciesF: Farenheit

Urban Subwatershed Restoration Manual 1x

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F-IBI: Fish Index of Biotic IntegrityFDC: Final Design and ConstructionFEMA: Federal Emergency Management AgencyGIS: Geographic Information SystemHCI: Hotspot Compliance InvestigationHSI: Hotspot Site InvestigationI: ImpactedIC: Impervious CoverICM: Impervious Cover ModelISS: Initial Subwatershed StrategyIRO: Inventory of Restoration OpportunitiesLWD: Large Woody DebrisMOA: Municipal Operations AnalysisMSI: Managing Stakeholder InputNARA: Natural Area Remnant AnalysisNCA: Needs and Capabilities AssessmentNCM: Neighborhood Consultation MeetingNPDES: National Pollutant Discharge Elimination SystemNS: Non-supportingNSA: Neighborhood Source AssessmentOMS: Ongoing Management StructurePAH: Polycyclic Aromatic HydrocarbonsPCB: Polychlorinated BiphenylsPCD: Project Concept DesignPER: Project Evaluation and RankingPMP: Performance Monitoring of ProjectsPSL: Priority Subwatershed ListRBA: Rapid Baseline AssessmentRBP: Rapid Bioassessment ProtocolREO: Restoration Education and OutreachRFC: Riparian Forest ContinuityRMI: Riparian Management InventoryRRI: Retrofit Reconnaissance InventoryRSAT: Rapid Stream Assessment TechniqueRv: Runoff CoefficientSCP: Source Control PlanSIR: Stakeholder Identification and RecruitmentSIS: Subwatershed Implementation StrategySMS: Sentinel Monitoring StationsSSD: Streets and Storm DrainsSTA: Subwatershed Treatment AnalysisSRI: Stream Repair InvestigationTPI: Tracking Project ImplementationTMDL: Total Maximum Daily LoadUD: Urban DrainageUSA: Unified Stream AssessmentUSGS: United States Geological SurveyUSSR: Unified Subwatershed and Site ReconnaissanceWGO: Watershed Goals and ObjectivesWRI: Watershed Reforestation InventoryWTM: Watershed Treatment Model

Urban Subwatershed Restoration Manual 1 1

Chapter 1: Organizing to Restore Urban Watersheds

This Manual presents the basic concepts usedto restore urban streams, and outlines anintegrated and practical framework forassessing restoration potential in small urbanwatersheds. The Manual is organized into sixchapters:

Chapter 1: Organizing toChapter 1: Organizing toChapter 1: Organizing toChapter 1: Organizing toChapter 1: Organizing toRRRRRestore Urban Westore Urban Westore Urban Westore Urban Westore Urban Watershedsatershedsatershedsatershedsatersheds

This chapter introduces the basic concepts oforganizing people to restore a local watershed.It begins by defining the language used to talkabout watersheds and their restoration. Next, itexplores national trends that are driving therapid growth of urban watershed restorationefforts, as well as the diverse local issues thatprompt restoration. Together, these nationaltrends and local issues shape the uniquerestoration goals that guide local restorationefforts. These goals often prescribe a desiredlevel of improvement in watershed health, asmeasured by a combination of physical,hydrologic, chemical, ecological or socialindicators. Chapter 1 makes a strong case fordefining these indicators in specific,measurable ways so that restoration progresscan be tracked and monitored.

Chapter 1 also describes the four basic groupsof stakeholders that must be engaged in localwatershed restoration efforts: the public,agencies, watershed partners, and potentialfunders. As all of these stakeholders mustinteract to develop and implement an effectivelocal restoration plan, the chapter concludes bydescribing how to build stakeholderinvolvement into the restoration planningprocess.

Chapter 2: Alteration of UrbanChapter 2: Alteration of UrbanChapter 2: Alteration of UrbanChapter 2: Alteration of UrbanChapter 2: Alteration of UrbanSubwatershedsSubwatershedsSubwatershedsSubwatershedsSubwatersheds

Effective restoration requires a keenunderstanding of how a subwatershed has beenaltered in the past. This chapter reviews eight

IntroductionIntroductionIntroductionIntroductionIntroduction

major subwatershed alterations that influenceurban streams and their prospects forrestoration. Alterations include the conversionof land to impervious cover; construction ofsewer, water and storm drain infrastructure;management of pervious areas; fragmentationof natural area remnants; interruption of thestream corridor; expansion and encroachmentof the floodplain; increased population density;and the creation of pollution hotspots.

Chapter 3: Impacts ofChapter 3: Impacts ofChapter 3: Impacts ofChapter 3: Impacts ofChapter 3: Impacts ofUrbanization on StreamsUrbanization on StreamsUrbanization on StreamsUrbanization on StreamsUrbanization on Streams

Given a knowledge of the intensity ofsubwatershed development, recent urbanstream research can help set realisticexpectations for urban restoration. This chapterpresents stream research within the context ofthe Impervious Cover Model (ICM). From arestoration standpoint, the ICM groups urbanstreams into three categories based on howmuch impervious cover exists in thesubwatershed: impacted streams, non-supporting streams and urban drainage. TheICM is then used to develop specificquantitative or narrative predictions for streamindicators for each of the three streamcategories. These predictions define theseverity of current stream impacts and theprospects for their future restoration.Predictions are made for five major types ofurban stream impacts: changes in streamhydrology, alteration of the stream corridor,stream habitat degradation, declining waterquality and loss of aquatic diversity. Waterquality impacts are further subdivided intopredictions concerning eutrophication,exceedance of bacterial standards, aquatic lifetoxicity, sediment contamination, and trash anddebris loading.

Introduction

Urban Subwatershed Restoration Manual 12


Chapter 4: RChapter 4: RChapter 4: RChapter 4: RChapter 4: Range of Aange of Aange of Aange of Aange of AvailablevailablevailablevailablevailableSubwatershed RSubwatershed RSubwatershed RSubwatershed RSubwatershed RestorationestorationestorationestorationestorationPPPPPracticesracticesracticesracticesractices

This chapter introduces the seven major groupsof restoration practices used to restore urbansubwatersheds. Four groups of practices aregenerally applied within the remaining streamcorridor: storm water retrofits, streamrestoration, riparian management, anddischarge prevention practices. Three groups ofpractices can be applied in the upland areas ofa subwatershed, including pervious areamanagement, pollution source control, andimproved municipal practice (although someon-site storm water retrofits can also beinstalled in upland areas). The chapterdescribes the many different restorationtechniques and discusses how they contributeto subwatershed restoration goals. The chapterconcludes with guidance on choosing the rightcombination of practices to meet specificrestoration goals, in the context of the actualrestoration potential of the subwatershed.

Chapter 5: EnvisioningChapter 5: EnvisioningChapter 5: EnvisioningChapter 5: EnvisioningChapter 5: EnvisioningRRRRRestorationestorationestorationestorationestoration

Urban restoration is both an art and a science,and it takes some skill to imagine thepossibilities for effective watershed restoration.This short chapter provides insight on how toenvision the prospects for effective restorationat the subwatershed level, and outlines somekey subwatershed characteristics that createthese opportunities. This chapter describes 11subwatershed features that offer opportunitiesfor subwatershed restoration practices. Theactual desktop and field assessment methodsused to find these restoration opportunities aredescribed in greater detail in Manuals 2, 10,and 11.

Chapter 6: A FChapter 6: A FChapter 6: A FChapter 6: A FChapter 6: A Framework toramework toramework toramework toramework toGuide SubwatershedGuide SubwatershedGuide SubwatershedGuide SubwatershedGuide SubwatershedRRRRRestorationestorationestorationestorationestoration

The last chapter introduces an eight-stepprocess to develop and implementsubwatershed restoration plans. Each step mayinclude tasks involving desktop analysis, rapidfield assessment, stakeholder involvement andmanagement products. The eight-stepframework can be used as a guide to develop,adopt, implement and track subwatershedrestoration plans. Manual 2 provides moredetail on the specific tasks and methods thatcan be used in subwatershed restorationplanning framework.

The next seven manuals provide more detailedguidance on each of the seven types ofwatershed restoration practices:

Manual 3: Storm Water Retrofit PracticesManual 4: Stream Repair PracticesManual 5: Riparian Management PracticesManual 6: Discharge Prevention PracticesManual 7: Watershed Forestry PracticesManual 8: Pollution Source Control PracticesManual 9: Municipal Practices and Programs

Each of these manuals describes techniques todesign and implement each restorationpractice, and provides detailed guidance on siteand subwatershed assessment methods. Inaddition, the manuals provide extensivereferences to other helpful resources for thedesign and construction of effective restorationpractices.

The final two manuals outline field methods toassess subwatershed restoration potential:

Manual 10: The Unified Stream Assessment (USA)

Manual 11: The Unified Subwatershed and Site Reconnaissance (USSR)

Introduction



Chapter 1: Organizing to RChapter 1: Organizing to RChapter 1: Organizing to RChapter 1: Organizing to RChapter 1: Organizing to RestoreestoreestoreestoreestoreUrban WUrban WUrban WUrban WUrban Watershedsatershedsatershedsatershedsatersheds

Each watershed restoration partnership isunique, both in terms of the goals that guide itand the stakeholders that participate in it. Thefive parts of this chapter explore how toorganize the partnerships needed to effectivelyrestore urban watersheds.

The first part of Chapter 1 defines the basicterminology used to talk about watersheds andrestoration. The second part examines the keytrends driving the rapid growth in urbanwatershed restoration in communities acrossthe country. The third part explores possiblegoals that can guide watershed restorationefforts and outlines how communities candevelop the most appropriate and achievablegoals. The fourth part describes the broadgroups of stakeholders that must be involved inrestoration plan development, while the fifthpart outlines practical strategies for organizingstakeholders toward a common purpose.

1.1 Getting the T1.1 Getting the T1.1 Getting the T1.1 Getting the T1.1 Getting the Terminology Righterminology Righterminology Righterminology Righterminology Right

The words “urban,” “watershed” and“restoration” can mean many things to manypeople, and when they are combined, it can bea recipe for confusion. So, from the outset, wewant to carefully define how each of theseterms is used throughout this manual.

Urban is defined as any watershed orsubwatershed with more than 10% totalimpervious cover.

Watersheds are land areas that drain surfaceand groundwater to a downstream water body,such as a river, lake or estuary. Watersheddrainage areas are large, ranging from 20 to100 square miles or more. Given their size,they may encompass many politicaljurisdictions, contain a mix of land uses(forest, agricultural, rural, suburban, urban),and have a broad range of pollution sources.Each watershed is composed of a number ofsmaller watersheds called “subwatersheds.”

Subwatersheds, as a general rule of thumb,have a drainage area of five to 10 square milesor less, and are the primary restoration unit inthe context of this manual. The small size ofsubwatersheds makes them ideal restorationcandidates for several reasons. First,subwatersheds can be rapidly mapped andassessed for restoration potential in a matter ofmonths, with an initial restoration strategyfollowing soon after. The small scale of asubwatershed also allows restoration practicesto be designed, constructed and assessed withina few years. Also, most subwatersheds arecontained within a single political jurisdiction,making it easier to coordinate localstakeholders. In our view, watershedrestoration can only be effectivelyimplemented at the subwatershed scale,although many subwatersheds may requirerestoration to achieve watershed goals.

Each urban subwatershed is drained by anetwork of perennial streams, each of whichcan be classified based on its relative order inthe network. For example, a small stream withno tributaries or branches is defined as a firstorder stream. When two first order streamscombine, they form a second order stream.Similarly, when two second order streams join,they create a third order stream, and so on.Given their relatively small drainage area, mosturban subwatersheds only contain streams thatrange from first to third order. The health ofthese smaller headwater streams is the majorfocus of urban restoration efforts.

The stream corridor and upland areas are thetwo parts of a subwatershed. Stream corridorsinclude the existing network of streamchannels and the lands that surround them.Upland areas include the remainingsubwatershed area that drains to the streamcorridor. The relationship between the streamcorridor and upland areas is depicted in Figure1. As subwatersheds urbanize, both the lengthand width of the stream corridor decline, andupland areas begin to dominate the landscape.



Figure 1: The Stream Corridor and Upland Areas in Urban SubwatershedsThe photo on the left illustrates a lightly developed subwatershed that has a relatively intact stream corridor

and stream network, which can be compared to a highly urban subwatershed where both features havebeen virtually eliminated.

Restoration is used throughout this manual inits broadest sense, and is defined as theapplication of any combination of restorationpractices that can improve stream health, asmeasured by improvements in physical,hydrological, chemical, ecological or socialindicators of stream quality. Alternative termssuch as “recovery,” “repair,” “rehabilitation,”or “enhancement” were considered, but foundinadequate. However, the use of the term“restoration” does not imply that fullecological restoration of an urban streams isalways possible.

Restoration practice is used to describe theseven broad groups of practices used to restoreurban subwatersheds. Four groups ofrestoration practices — storm water retrofits,stream restoration, riparian management anddischarge prevention — are generally appliedwithin the urban stream corridor. Theremaining three groups of practices —pollution source control, pervious areamanagement and municipal stewardship —are normally applied to upland areas of asubwatershed.

Stakeholders are defined as any agency,organization or individual involved in oraffected by the decisions made in asubwatershed restoration plan. From a practical

standpoint, it helps to think of four broad groupsof stakeholders in each restoration effort:agencies, the public, watershed partners andpotential funders. Each of these fourstakeholder groups is further defined later inthis chapter.

1.2 T1.2 T1.2 T1.2 T1.2 Trends Driving Growth inrends Driving Growth inrends Driving Growth inrends Driving Growth inrends Driving Growth inUrban WUrban WUrban WUrban WUrban Watershed Ratershed Ratershed Ratershed Ratershed Restorationestorationestorationestorationestoration

The remarkable growth in urban watershedrestoration efforts has been fueled by severalintersecting trends affecting thousands ofcommunities across the nation: the need tocontrol nonpoint source pollution, newregulatory mandates, increased municipalrestoration capability, growth in urbanwatershed organizations, and greater publicexpectations for cleaner and greenerneighborhoods.

Need to Control Nonpoint PNeed to Control Nonpoint PNeed to Control Nonpoint PNeed to Control Nonpoint PNeed to Control Nonpoint PollutionollutionollutionollutionollutionSourcesSourcesSourcesSourcesSources

Most communities have clamped down onpoint sources of pollution to the furthest extentpossible (e.g., sewage treatment plants andindustrial discharges). Despite a multi-billiondollar investment over the last three decades,



however, many urban streams and rivers still donot meet water quality standards and continueto experience severe habitat degradation.Consequently, communities are now shiftingtheir control efforts to reduce nonpoint sourcesof pollution in order to meet clean water goals.In urban watersheds, nonpoint source controlusually means better treatment of urban stormwater runoff, which is best accomplished at thewatershed or subwatershed scale.

EmerEmerEmerEmerEmerging Rging Rging Rging Rging Regulatoregulatoregulatoregulatoregulatory Driversy Driversy Driversy Driversy Drivers

A series of state and federal regulations arealso prompting many communities to restoretheir urban watersheds. For example, whenurban waters do not meet water qualitystandards prescribed under the Clean WaterAct, agencies must develop pollutant reductionplans that show how these standards can beattained in the future. These plans, known asTotal Maximum Daily Loads (or TMDLs), mayrequire communities to implement restorationpractices to reduce nonpoint source pollutantloads by specific amounts over a definedtimetable.

In addition, many communities are nowregulated under EPA’s storm water NPDESpermit program, which covers pollutantsdischarged from municipal storm drainsystems. The municipal permit program appliesto communities with populations of more than50,000. Under these permits, communitiesmust demonstrate that they have localprograms to manage storm water, detect andeliminate illicit discharges, prevent pollution,and educate and involve the public. Largercommunities are also responsible formonitoring the quality of their storm waterrunoff. A few states have even gone so far as tostipulate that a fixed percentage of eachcommunity must be restored during eachpermit cycle. As a result, many of the localprograms required under municipal NPDESstorm water permits support stronger localrestoration programs (CWP, 2003).

Communities may also engage in watershedrestoration to comprehensively addressnumerous other federal environmentalmandates, control programs, and policies.

Examples include the EPA minimum measuresto control combined sewer overflows (CSOs)and sanitary sewer overflows (SSOs), as wellas source control measures that may berequired under the Safe Drinking Water Act.Other federal agencies also encourage awatershed approach. A notable example is theNational Flood Insurance Program (FEMA),which encourages watershed-based solutions tolocal flooding problems. In addition, watershedefforts to recover salmon populations in thePacific Northwest have been prompted by theEndangered Species Act. Similar efforts havebeen triggered in the Texas hill country toprotect the endangered Barton Springssalamander. Many federal agencies activelypromote watershed restoration through newgrant programs that support research anddemonstration of wetland restoration, streamrestoration, nonpoint source control and urbanforestry practices.

Communities often find it a challenge tointegrate the many state and federal regulatorydrivers into a coherent whole, since theyoperate over many different watershed unitsand address multiple environmental endpoints.Urban watershed restoration planning offers auseful framework for this integration.

Increased LIncreased LIncreased LIncreased LIncreased Local Rocal Rocal Rocal Rocal RestorationestorationestorationestorationestorationCapabilityCapabilityCapabilityCapabilityCapability

In recent years, communities have greatlyexpanded the type and scope of their watershedrestoration activities. For example, the Centerrecently surveyed more than 50 communities ofall sizes to measure their current activity inurban watershed restoration. The averagecommunity had engaged in at least 10 of the 17core restoration programs recommended as partof a local Smart Watersheds Program (CWP,2004). Table 1 presents some of the interestinghighlights from the survey. As can be seen, atleast half of the communities reported somelevel of activity in many areas of urbanwatershed restoration. This finding suggeststhat more staff, programs, funding andmapping are available to support urbanwatershed restoration than ever before, andcommunities are rapidly acquiring morepractical skills and experience to implement



restoration practices. At the same time, thesurvey revealed that most local restorationefforts were still in an experimental ordemonstration stage, and few communities hadsystematically integrated their restorationefforts at the subwatershed scale.

Growth in Urban WGrowth in Urban WGrowth in Urban WGrowth in Urban WGrowth in Urban WatershedatershedatershedatershedatershedOrOrOrOrOrganizationsganizationsganizationsganizationsganizations

The recent growth of nonprofit watershedgroups has also been impressive. More than4,000 watershed groups are now establishedacross the country, along with an equal numberof land trusts, smart growth and “friends of”organizations. A majority of these groups arelocated in suburban or urban watersheds (CWP,2002). The number, sophistication, andexpectations of urban watershed groups haveall increased sharply in recent years. Thesegroups can exert considerable pressure to getcommunities to do a better job in restoringtheir urban watersheds. While urban watershedgroups may often be impatient for results, theyare becoming more effective advocates forlocal restoration.

PPPPPublic Demand for Better Lublic Demand for Better Lublic Demand for Better Lublic Demand for Better Lublic Demand for Better LocalocalocalocalocalEnvironmentEnvironmentEnvironmentEnvironmentEnvironment

Urban and suburban residents are concernedabout the overall quality of life in theirneighborhoods, and these concerns oftenextend beyond healthier streams. Residents areconcerned about issues such as greenways,flooding, waterfront improvements, aesthetics,trash, and neighborhood revitalization. Inaddition, the public has a stronger awarenessabout local stream quality, and activelyparticipates in both personal and watershedstewardship activities. The net effect is that thepublic is demanding better stream protection,and expects their community concerns to befully integrated within the watershedrestoration planning process.

1.3 Many Different Goals Guide1.3 Many Different Goals Guide1.3 Many Different Goals Guide1.3 Many Different Goals Guide1.3 Many Different Goals GuideUrban WUrban WUrban WUrban WUrban Watershed Ratershed Ratershed Ratershed Ratershed Restorationestorationestorationestorationestoration

No two urban watershed restoration efforts areever alike. Each restoration effort has its ownunique goals, which are shaped by thewatershed scale, various restoration “drivers”and stakeholder input. This section reviews theimpressive diversity of goals driving localwatershed restoration efforts across thecountry. A sample of watershed restorationgoals is depicted in Figure 2; mostcommunities choose multiple goals to guidetheir watershed plan. In general, mostrestoration goals can be lumped into one offour broad categories: water quality, physical/hydrological condition, biological diversity andcommunity concerns.

Watershed restoration goals may be orientedtoward the stream, the stream corridor, orupland areas, or some combination of all three.In addition, local restoration goals frequentlydiffer in ambition. For example, somecommunities set goals with prevention in mind,e.g., simply to keep something bad fromhappening, like a pollution spill, flood damage,or sewage overflows. Other communities seekto systematically repair a problem (or set ofproblems) in the stream or its corridor, such asan eroding bank, a fish barrier or an inadequateforest buffer. The most ambitious communities

Table 1: Selected Results of National Survey of Municipal Watershed Restoration Activity

Restoration Activity or Practice Communities Reporting Activity (%)

Small Watershed Planning 55

Subwatershed GIS Mapping 80

Rapid Stream Assessment 49

Storm Water Retrofitting 53

Stream Restoration 51

Discharge Prevention 63

Urban Forestry 49

Watershed Education 65

Hotspot Pollution Prevention 35

Public Involvement 71 Note: 50 + communities surveyed, with populations ranging from 25,000 to 2,000,000. Restoration activity tended to be slightly higher in communities with larger populations and in those covered by Phase I storm water NPDES permits. For complete survey results, consult CWP (2004)



set goals to improve conditions within thestream or its corridor. These communities seeka defined and measurable improvement for adesired indicator in stream health bycomprehensively applying many restorationpractices across a subwatershed.

The choice of whether to set goals to prevent,repair or improve problems depends on theactual restoration opportunities within asubwatershed. These opportunities depend onat least three subwatershed factors: percent

impervious cover, the length of intact streamcorridor, and the fraction of the subwatershedthat can be effectively treated by restorationpractices. Consequently, communities oftenneed to reconcile broad watershed restorationgoals with the limited restoration potential ofthe many subwatersheds that comprise it. Thebalance between proposing ambitious goals atthe watershed level and the ability torealistically achieve them in individualsubwatersheds is a major theme of this manual.

Source: USDA NRCS

Figure 2: General Classification of Watershed Restoration Goals Many different goals can be selected to guide watershed restoration; most communities

choose several different goals relating to water quality, biological, physical, and community indicators.

• Reduce pollutants of concern (e.g. TSS, N, P, Zn, Cu,hydrocarbons, pesticides)

• Prevent illegal discharges/spills• Meet water quality standards• Reduce sediment contamination• Allow water contact recreation• Protect drinking water supply

• Restore aquatic diversity• Restore wetlands/natural areas• Expand forest cover• Restore/reintroduce species (e.g. salmon)• Improve fish passage• Enhance wildlife habitat• Remove invasive species• Keep shellfish beds open• Enhance riparian areas

• Increase groundwater recharge• Reduce channel erosion• Reclaim stream network• Reduce flood damage• Reconnect floodplain• Restore physical habitat• Protect municipal infrastructure

• Eliminate trash/debris• Create greenways/waterfront access/open space• Revitalize neighborhoods• Improve aesthetics/beautification• Increase citizen awareness• Improve recreation opportunities• Increase fishing opportunities

Water Quality

Biological

Physical/Hydrological

Community



1.4 The Role of Stakeholders1.4 The Role of Stakeholders1.4 The Role of Stakeholders1.4 The Role of Stakeholders1.4 The Role of Stakeholdersin Win Win Win Win Watershed Ratershed Ratershed Ratershed Ratershed Restorationestorationestorationestorationestoration

While restoration is driven by the goals ofthose that care for the watershed, aligning theefforts and resources of stakeholders towardscommon goals is critical to the adoption andimplementation of any restoration plan.Ideally, the goals and vision for the watershedshould be developed early in the restorationprocess, based on input from a broad group ofstakeholders. Consequently, you need to knowthe key stakeholders in the watershed, andinclude them in virtually every step of therestoration process.

The term stakeholder is loosely defined as anyagency, organization, or individual that isinvolved in or affected by the decisions madein a watershed plan. In theory, this definitionincludes just about everybody; in reality, itmerely refers to those folks that actually showup to speak their mind.

Not all stakeholders are equal, however. In aliteral sense, each has a different stake in theoutcome of the plan, and is expected toperform a different role in the watershedrestoration effort. Each comes to the table withvarying degrees of watershed awareness,concern and/or expertise. Stakeholders alsohave different preferences as to how, when, andin what manner they want to be involved in theprocess. As a result, the outreach methods usedto educate and inform stakeholders must becarefully calibrated to match their differentlevels of knowledge and understanding. Forexample, some stakeholders are daytimeprofessionals expected to be at the tablebecause of their job duties, whereas others are“night-timers” donating their time andexpertise. Effective watershed managersrecognize the wide diversity in stakeholders,and structure their planning process to providemultiple options and opportunities forinvolvement.

Stakeholders usually fall into one of fourdistinct groups that interact to producerestoration plans, as shown in Figure 3. Thefour groups include the public, agencies,watershed partners and potential funders.

Conceptually, stakeholder involvement can beviewed as a pyramid, with expanding levels ofinvolvement. The base of the pyramid containsthe greatest number of stakeholders, many ofwhom are initially unaware of watershedproblems and their potential role in restoration.The awareness and involvement ofstakeholders becomes progressively greatertoward the top of the pyramid. Stakeholdersfound at the apex of the pyramid represent keydecision-makers, and are generally consideredthe champions for restoration. The next sectiondescribes each of the four stakeholder groupsin more detail.

Agency StakAgency StakAgency StakAgency StakAgency Stakeholderseholderseholderseholderseholders

Local government has primary responsibilityfor urban watershed restoration. In reality,these responsibilities are usually spread over awide assortment of bureaus, departments,agencies and divisions that rarely coordinatemuch with each other. As a result, it is useful tothink of all these individuals and units asoccupying different levels of the stakeholderpyramid (Figure 4). The apex of the pyramidconsists of the elected officials and the leadlocal restoration agency that are the championsof restoration, and who act to coordinate theactions of all other units of local government.Elected officials are critical stakeholders sincethey must vote to approve budgets forrestoration plans.

The next tier consists of agencies that dealdirectly with local environmental issues orservices, followed by agencies that own orcontrol land where restoration practices may beconstructed (e.g., schools, parks, etc.). Thenext rung is occupied by local agencies thatmay not initially perceive restoration as a corepart of their mission. A good example is a localplanning and zoning authority that cancontribute to subwatershed restoration byadopting better development standards forinfill and redevelopment.

The bottom of the pyramid consists of stateand federal agencies that regulate water qualityor protect natural resources. These agencies arecritical, since they may need to approvepermits for restoration practices or even



Restoration Plan

Partners

Agency

Funders

Public

Figure 3: Four Types of Stakeholders Involved in Watershed Restoration Plans

Figure 4: The Agency Stakeholder PyramidDozens of local, state and even federal agency stakeholders need to be involved to coordinate

effective local restoration planning.

State DEP/DNR; EPA; Corps of Engineers

Schools and Parks; Planning and Zoning Authority

Planning Department; Community Forestry; Conservation District

Department of Public Works; Department of Environmental Protection

Elected Officials

Lead Restoration Agency

Local Environmental Agencies

Land owning or Land Regulating Agencies

State and Federal Agencies

Mayor; Council; Planning Commission



approve the restoration plan itself (e.g., in thecase of a TMDL). Some agencies can alsolend staff expertise and provide monitoring andmapping data to support the restoration effort.

The PThe PThe PThe PThe Publicublicublicublicublic

The public is a major stakeholder in everywatershed restoration effort, although asindividuals they may be unaware of this role.Indeed, watershed awareness and activismvaries considerably among the public, and canbe best understood in terms of a pyramid(Figure 5). The general public make up thebottom of the pyramid, and initially possess alow level of watershed awareness orinvolvement. Indeed, much of what they knowabout watersheds comes from the local paperor evening news. Increasing the awareness ofthe general public is important, given that thecollective impact of their individual actionscan improve or degrade watershed health.

The next level of the pyramid is occupied bythe receptive public. As voters, they maysupport stronger local environmentalinitiatives, and might be willing to changedaily behaviors to protect the watershed, suchas installing rain barrels, planting trees orpicking up after their pets. Education, outreachand direct municipal services may often beneeded to improve personal stewardship amongthe receptive public.

The next subset is the adjacent public, whichincludes people that live near the streamcorridor and will be positively or negativelyaffected by any restoration practicesconstructed within it. Since they have such adirect stake in the outcome of restoration, thisgroup must be continuously informed as tohow restoration practices will influence theirneighborhood and property values.

The activist public occupies the next rung onthe pyramid. This group consists of communityleaders in neighborhood associations, civicgroups, garden clubs, recreational enthusiasts,and the like. While watershed restoration maynot be their main mission, the activist publicoften recognizes its potential benefits for thecommunity. Enlisting the activist public in the

restoration cause can be very important, giventhe strong influence they exert both in thecommunity and on the local political process.

The apex of the pyramid is occupied bywatershed groups that are organized toadvocate for urban watersheds and helpimplement local restoration plans. Fewsubwatersheds possess such a group at thebeginning of the restoration process, but theyshould always have one at the end.

WWWWWatershed Patershed Patershed Patershed Patershed Pararararartnerstnerstnerstnerstners

The watershed partners stakeholder groupconsists of non-local government partners thatare expected to perform many important rolesin watershed restoration. Figure 6 depicts thediversity of watershed partners involved inlocal restoration.

Responsible parties include utilities whoseactivities or discharges are regulated by permitor ordinance. The goal is to align theirpollution control efforts with the goals forwatershed restoration.

Local media are also valuable watershedpartners, since they have the best means tobroadcast information about watershedrestoration to the general public through localtelevision, community newspaper and radio.Restoration requires a lot of expertise, andlocal advisors are the stakeholders that canbring it to the table. Examples of local advisorsinclude engineers, environmental consultants,local scientists and educators. In addition,many non-profit organizations and regionalplanning agencies can contribute data andexpertise to the watershed restoration effort.

Local businesses and landowners can bevoluntary watershed partners, although theyoften start with a low level of awareness ormay be suspicious of potential regulation.However, it is very important to enlist theircooperation to improve stewardship on thelands they own and the operations they control.



Figure 5: The Public Stakeholder PyramidPublic stakeholders are not monolithic, but can be stratified on the basis of their awareness,stewardship activities, and interest in participating in the local watershed restoration process.

Everyone who lives and works in the watershed

Community Leaders; PTAs; Schools; Churches; Interested Citizens; Voters

Property owners near proposed restoration project sites

Neighborhood Associations; Civic Groups; Garden Clubs; Greenway Coalitions; Anglers’ Groups; Recreation/Hiking Group

Watershed Groups

Activist Public

Adjacent Public

Receptive Public

General Public

Watershed Organizations

Chamber of Commerce; Private Schools; Colleges/Universities; Industry; Builder/Developers; Real Estate Companies

Engineers; Environmental Groups and Consultants; Local Scientists; Educators; Non-Profits; Regional Planning Agencies

Responsible

Parties

Local Media

Local Advisors

Local Businesses and Landowners

NPDES Regulated Dischargers; Local Utilities

Figure 6: The Partner Stakeholder PyramidMany different partners comprise this diverse stakeholder group asked to perform many roles in

watershed restoration, including implementing pollution controls, spreading the restoration message,providing expertise, and integrating restoration goals into their normal operations.



Foundations; Corporations; Individuals

EPA; Corps of Engineers; Fish and Wildlife Service

State Environmental Agency (grants); State Resource Protections (grants)

Local Government

State

Federal

Private

Agency Heads; Budget Experts; Elected Officials

FFFFFundersundersundersundersunders

Funding partners are the stakeholders expectedto finance watershed restoration at some pointin the future. The diversity of fundingstakeholders can also be viewed in terms of apyramid (Figure 7). The top of the pyramid isoccupied by local government who has theprimary responsibility to finance restoration,especially during the early planning stages. Themost common local revenue streams areoperating budgets, capital budgets and stormwater utilities. Most communities are alreadyspending more money than they think onrestoration activities, although these costs arefrequently spread across many different agencybudgets. Clearly, the agency heads, budgetexperts, and elected officials that control localpurse strings are important individualstakeholders, and they need to becontinuously educated on how restorationbenefits the community and why therestoration investment is justified.

The next two levels on the funding pyramid areoccupied by state and federal fundingsources, which can provide grants, loans ordirect technical services to supplement localrestoration investments. State and federalfunding stakeholders usually get many morefunding requests than they can meet, so it isimportant to emphasize why the localwatershed should be a top priority for fundingand to demonstrate the width and breadth ofthe local restoration partnership. The last rungof the pyramid is occupied by private fundingsources. This diverse group of funders includesfoundations, corporations, and individuals thatcan provide supplemental funding for selectedrestoration tasks. Private funding sources liketo give to people, and see on-the-ground resultsat the community scale. Consequently, theytend to support grassroots watershedorganizations rather than local governments.All funding stakeholders should be viewed asinvestors, and should be continuously updatedabout the costs of restoration and the benefits itprovides to the community.

Figure 7: The Funder Stakeholder PyramidThis group of stakeholders constitutes the major investors in local watershed restoration.

Stakeholders near the top of the pyramid usually provide the greatest share of overall funding,but a targeted education strategy is always needed to cultivate each group of potential

investors.



1.5 Organizing Stakeholders1.5 Organizing Stakeholders1.5 Organizing Stakeholders1.5 Organizing Stakeholders1.5 Organizing StakeholdersInto ActionInto ActionInto ActionInto ActionInto Action

There is no single path to successfully involveall four stakeholder groups in the watershedrestoration process. However, it is a goodpractice to involve them early and often, andparticularly when setting the goals that drivethe restoration effort. Manual 2 presents aseries of methods for involving each of the fourstakeholder groups during each step of therestoration process. Each method seeks toachieve a unique purpose, is targeted to adifferent combination of stakeholders, andemploys customized outreach techniques. Theultimate goal is to organize stakeholders tocreate a strong partnership that can attractpolitical support for the restoration plan.

Stakeholder involvement helps ensure that therestoration plan is realistic, scientificallysound, and reflects community values anddesires. When the right mix of stakeholdersagrees on clear and measurable goals, it cancreate a powerful impetus to guide restorationdecisions.

Many consider watershed restoration toprimarily be a technical endeavor, and it iscertainly true that many technical skills areneeded. In practice, however, successfulrestoration is mostly about organizing peopleand resources around common goals. Manynon-technical skills must be learned to makerestoration happen, such as coordination,communication, outreach and leadership.




Chapter 2: The Alteration of Urban Subwatersheds

Chapter 2: The Alteration of UrbanChapter 2: The Alteration of UrbanChapter 2: The Alteration of UrbanChapter 2: The Alteration of UrbanChapter 2: The Alteration of UrbanSubwatershedsSubwatershedsSubwatershedsSubwatershedsSubwatersheds

The current state of an urban stream reflectspast alterations to its subwatershed. These pastsubwatershed alterations must be fullyunderstood before you can begin to make senseof an urban stream, set restoration goals oreven think about prescribing the rightrestoration practices. This chapter reviews theways in which hundreds of past humanalterations collectively transform the characterof urban subwatersheds into a complex mosaicof pervious and impervious areas, both ofwhich are extensively modified by humans.

Subwatersheds are progressively transformedand disturbed over the course of many decadesor even centuries. Subwatersheds experience atleast eight major alterations that are significantfrom the standpoint of restoration:

1. Conversion to Impervious Cover2. Construction of Sewer, Water, and Storm Water Infrastructure3. Intensive Management of Pervious Areas4. Fragmentation of Natural Area Remnants5. Interruption of the Stream Corridor6. Encroachment and Expansion in the Flood Plain7. Increased Population Density8. Increased Density of Storm Water Hotspots

The cycle begins with the clearing of forests,farms and wetlands, which are replaced byrooftops, roads, parking lots and other forms ofimpervious cover (IC). By our definition, urbansubwatersheds can range from 10 to nearly100% IC. The imprint of the built environmenton subwatersheds of progressively greaterimpervious cover is clearly evident in Figure 8.Impervious cover fundamentally alters thehydrology of urban subwatersheds bygenerating increased storm water runoff andreducing the amount of rainfall that soaks intothe ground. Impervious cover is also the bestindicator to measure the intensity ofsubwatershed development and predict theseverity of impacts to the remaining streamnetwork (CWP, 2003).

2.1 Conversion to2.1 Conversion to2.1 Conversion to2.1 Conversion to2.1 Conversion toImperImperImperImperImpervious Covervious Covervious Covervious Covervious Cover



Figure 8: Six Urban Subwatersheds With Progressively Greater Impervious Cover The imprint of IC is clearly evident in these six aerial photos of small urban subwatersheds with progressively greater IC.

Note how both the stream network and corridor are diminished at higher levels of IC. Subwatershed IC is a key variable to assess the prospects for stream restoration.

Pipe Outfall

a) 10% Impervious Cover

d) 50% Impervious Cover

f) 80% Impervious Cover

c) 30% Impervious Cover

e) 60% Impervious Cover

b) 20% Impervious Cover



Urban subwatersheds are serviced by anenormous network of underground water,sewer, and storm drain pipes. Hundreds ofmiles of pipes can be found in a subwatershedas small as five square miles. Each kind of pipehas a pervasive influence on the subwatershedand can also severely constrain the location ofrestoration practices.

For example, sanitary sewer pipes oftenparallel the stream network and can become asource of sewage leaks and overflows. In othercases, sewer pipes can capture groundwaterthat would otherwise sustain stream flow.Since sewers often cross the stream network,they can also become barriers to fish migration.Even the network of pipes that supplies waterto homes can influence the subwatershed.Depending on their age and condition, waterdistribution pipes can lose 10 or even 20% oftheir water volume to the stream.

Urban subwatersheds also possess an extensivenetwork of storm drain pipes that deliver stormwater flows rapidly and efficiently to thestream. This efficiency comes at anenvironmental cost, as storm drains increasedownstream floods and deliver pollutantsentrained in storm water runoff. Storm drains“short circuit” natural riparian areas, whichreduces their effectiveness in removingpollutants. Storm drain pipes can also causesevere localized erosion at their outfalls, unlessthey are extensively armored.

2.2 Construction of2.2 Construction of2.2 Construction of2.2 Construction of2.2 Construction ofSewerSewerSewerSewerSewer, W, W, W, W, Wateraterateraterater, and Storm, and Storm, and Storm, and Storm, and Storm

WWWWWater Infrastructureater Infrastructureater Infrastructureater Infrastructureater Infrastructure

2.3 Intensive Management2.3 Intensive Management2.3 Intensive Management2.3 Intensive Management2.3 Intensive Managementof Pof Pof Pof Pof Pererererervious Areasvious Areasvious Areasvious Areasvious Areas

When subwatersheds are viewed from the air,areas of impervious cover are seen interspersedwithin a larger matrix of pervious areas. Mostof the remaining pervious areas have beenhighly disturbed in the past and few retain thesoil and vegetation qualities they oncepossessed. The most fundamental change iscaused by the disturbance of native soils.Progressive cycles of development andredevelopment involve wholesale earthmoving;erosion or removal of topsoil; compaction ofsubsoils; and the filling of depressions,wetlands and natural rainfall storage areas.Consequently, the soils of urban pervious areasoften lack the fertility, tilth, and rechargecharacteristics of their non-urban counterparts(Schueler, 2000). From a practical standpoint,the hydrology of many urban pervious areas ismore similar to impervious areas than naturalones.

The vegetative cover of pervious areas rangesfrom bare earth to urban forest, but themajority is managed as turf grass or lawn.Most pervious areas are continuously mowedto arrest the natural pattern of vegetativesuccession. While there is some tree cover inmost urban subwatersheds, most urban “forest”has less than 50% canopy coverage (AmericanForests, 2001). As a result, urban forests lackthe structure and understory of their ruralcounterparts, and are often dominated by non-native trees, shrubs and vines.



A few isolated fragments of forests andwetlands always seem to persist in urbansubwatersheds. A typical pattern is depicted inFigure 9, which shows the distribution of forestand wetland remnants in the Watts Branchsubwatershed located in suburban Maryland.Often, natural area remnants are located inareas that were extremely difficult to develop(e.g., steep slopes), were abandoned and have

2.4 F2.4 F2.4 F2.4 F2.4 Fragmentation ofragmentation ofragmentation ofragmentation ofragmentation ofNatural Area RNatural Area RNatural Area RNatural Area RNatural Area Remnantsemnantsemnantsemnantsemnants

Figure 9: Distribution of Natural Area Remnants ina Non-Supporting Subwatershed

Although Watts Branch (Rockville, MD) has nearly 30% IC,it still contains significant forest and wetland fragments in

its subwatershed, many of which are found in closeproximity to the stream corridor.

since regrown, or grew up over time withinparks, cemeteries and public open space. Inother situations, subwatershed alterations causechanges in local hydrology that unintentionallycreate new urban wetlands. Common examplesinclude old ponds, backwaters behind roadcrossings, and abandoned earthworks.Although of relatively recent origin, thesewetlands may receive some protection understate or federal wetland protection statutes.

Forest and wetland remnants are often isolatedand have little or no connection with othernatural habitats or the stream corridor.Typically, natural area remnants have a greaterproportion of edge habitats compared to corehabitats. Natural area remnants are particularlysusceptible to invasions of non-native speciesof both plants and animals, and it is notuncommon for invasive species to becomenumerically dominant. Natural area remnantsare also stressed by storm water runoff andurban heat island effects. As disturbed andisolated as they are, natural area remnants haveintrinsic value as examples of nature in thecity, and may present excellent opportunitiesfor restoration in their own right.

2.5 Interruption of the2.5 Interruption of the2.5 Interruption of the2.5 Interruption of the2.5 Interruption of theStream CorridorStream CorridorStream CorridorStream CorridorStream Corridor

Some kind of stream corridor remains in all butthe most extremely developed subwatersheds,if for no other reason than it is usually tooexpensive to totally enclose all streams inpipes. The stream corridor that remains,however, is highly interrupted (i.e., it isfrequently crossed, culverted, channelized,ditched, enclosed, armored or otherwise“improved”). Each of these types ofinterruptions can be found in the Maiden’s



Choice subwatershed located in Baltimore, MD(Figure 10). The subwatershed has about 40%impervious cover and experiences extensivechannel alteration and interruption throughoutits headwaters and main stem. In many ways, itresembles a broken pipe more than a streamnetwork.

Figure 10: Stream Interruption in a Non-Supporting SubwatershedThis stream network of this Baltimore (MD) subwatershed has been extensively

interrupted by road crossings, extended culverts, channelization and other engineering“improvements” over many decades. Most first order streams are not shown on the mapbecause they have been enclosed by storm drains. Stream interruption is an important

factor in determining fish passage, channel erosion, and aquatic habitat suitability.

The natural flood plain has always been anattractive but dangerous area in which to build,and communities have historically proceededwith development in these areas. In order toprotect buildings from flood damage,landowners have incrementally modified theflood plain to allow development. The mostcommon modification has been to fill the flood

2.6 Encroachment and2.6 Encroachment and2.6 Encroachment and2.6 Encroachment and2.6 Encroachment andExpansion in the Flood PlainExpansion in the Flood PlainExpansion in the Flood PlainExpansion in the Flood PlainExpansion in the Flood Plain

plain with earth to provide a higher platformfor buildings. While the fill may provide localrelief to landowners, it also sharply reduces thecapacity of the flood plain and exacerbatesdownstream flooding problems. Other floodcontrol remedies such as channelization,levees, and armoring produce similar effects. Inaddition, the frequent stream crossings foundin urban subwatersheds can encroach on theflood plain. Undersized bridges or culverts thatcross the flood plain may also reduce thecapacity of the flood plain to handle floodwaters.

Even if encroachment never occurred, urbanflood plains will always expand in response toupstream development. Urban subwatershedsproduce higher peak flooding rates;consequently, urban flood plains must expandto accommodate these higher flows. Both theheight and width of the urban flood plainincrease, so that when floods occur, moreproperty is subject to inundation. Indeed, manyurban subwatersheds are experiencing floodplain expansion, while at the same time theyare losing flood plain capacity due toencroachment. Flood damages are theinevitable result.



Urban subwatersheds are home to manyhumans, pets and wildlife. Each of thesepopulations can directly generate pollutants,such as bacteria or nutrients that can movefrom the subwatershed to the stream. Humans,presumably the most intelligent of the threegroups, make daily decisions that can eitherimprove or degrade conditions in asubwatershed. Negative choices such asdumping, littering, over-fertilizing or notpicking up after a dog can directly diminishstream quality when these actions aremultiplied many times over. On the other hand,positive choices such as installing rain barrels,adopting streams or planting trees can improvestream quality, particularly when they occur ona widespread basis. Thus, the collectiveattitudes, awareness and behaviors ofsubwatershed residents determine whetherpollution will be generated or prevented.

2.7 Increased2.7 Increased2.7 Increased2.7 Increased2.7 IncreasedPPPPPopulation Densityopulation Densityopulation Densityopulation Densityopulation Density

2.8 Increased Density of2.8 Increased Density of2.8 Increased Density of2.8 Increased Density of2.8 Increased Density ofStorm WStorm WStorm WStorm WStorm Water Hotspotsater Hotspotsater Hotspotsater Hotspotsater Hotspots

The density of storm water pollution hotspotsincreases as subwatersheds become moreintensively developed. Hotspots are defined ascommercial, industrial, institutional, municipal,and transport-related operations that tend toproduce higher levels of storm water pollution,or present a higher potential risk for spills,leaks and illegal discharges. The nature anddistribution of storm water hotspots is differentin each urban subwatershed, but there arealways quite a few of them, many of which arequite small. Considerable detective work isneeded to find storm water hotspots and toprevent potential pollution discharges that canimpair downstream water quality.

Together, these eight subwatershed alterationsdiminish the quality of streams anddownstream waters. The next chapter reviewshow these alterations impact streams, and howthey can be predicted on the basis ofsubwatershed impervious cover.


Chapter 3: Impacts of Urbanization on Streams

Chapter 3: Impacts of UrbanizationChapter 3: Impacts of UrbanizationChapter 3: Impacts of UrbanizationChapter 3: Impacts of UrbanizationChapter 3: Impacts of Urbanizationon Streamson Streamson Streamson Streamson Streams

This chapter summarizes recent research onthe impact of urbanization on stream qualityfor subwatersheds with more than 10%impervious cover (IC). In general, changes instream quality can be tracked according to fivebroad indicators:

1. Changes to stream hydrology2. Physical alteration of the stream corridor3. Stream habitat degradation4. Declining water quality5. Loss of aquatic diversity

Figure 11 outlines different stream impacts thatcan occur within each indicator category(CWP, 2003). This chapter describes howurban stream quality is related to subwatershedIC, and how stream restoration can be assessedwithin the context of the Impervious CoverModel (ICM).

Impervious cover is often used as a generalindex of the intensity of subwatersheddevelopment and the presumed severity of theseven other subwatershed alterations discussedin the last chapter. The relationship betweensubwatershed IC and stream quality indicatorscan be predicted by the ICM, which is basedon hundreds of research studies on first tofourth order urban streams (CWP, 2003). It isimportant to keep in mind that the ICM is aguide and not a guarantee: ICM streamindicator predictions are general, and will notapply to every stream within the ICMclassification. Urban streams are notoriouslyvariable, and factors such as gradient, streamorder, stream type, age of subwatersheddevelopment, and past management practicescan and will make some streams depart fromthese predictions. In general, subwatershed ICcauses a continuous but variable decline inmost stream indicators in a stream category.

Therefore, the severity of impacts tends to begreater at the high end of the IC range withineach stream category.

The ICM is a simple tool that identifies threeclassifications of urban streams, according totheir current health and future restorationpotential (Figure 12). The three types ofstreams are as follows:

Impacted Streams have between 10 and 25%subwatershed IC, and show clear signs ofdeclining stream health. Most indicators ofstream health fall in the fair range, althoughsome reaches may still be rated as being ofgood quality. These streams often exhibit thegreatest restoration potential since theyexperience only moderate degradation, have anintact stream corridor, and usually have enoughland available in the subwatershed to installrestoration practices.

Non-Supporting Streams range between 25and 60% subwatershed IC, and no longersupport their designated uses1, as defined byhydrology, channel stability, habitat, waterquality and biological indicators.Subwatersheds at the lower end of the IC range(25 to 40%) may show promise for partialrestoration, but are so altered that theynormally cannot attain pre-developmentconditions for most indicators. In somecircumstances, streams in the upper range ofthe non-supporting category (40 to 60% IC)may show some potential for streamrestoration. In most circumstances, however,the primary restoration goals are to reducepollutants, improve the stream corridor, orenhance community amenities.

1 The term “designated uses” has a regulatory connection with respect to the Clean Water Act, in terms of a water body’s capacityto support fishing, swimming, and other human uses as determined by compliance with applicable water quality standards andnarrative biological criteria.



• Increased annual storm water runoff • Diminished baseflow (in some streams) • Increased peak discharge for 100-year storm event • Increased frequency of bankfull flooding

Figure 11: Five Groups of Stream Impacts Associated with Urban Subwatersheds

• Stream enclosure/modification • Loss of riparian forest continuity • Stream interruption • Floodplain disconnection • Increased stream crossings

• Channel enlargement • Greater annual sediment yield • Declining stream habitat indexes • Diminished large woody debris • Increased summer stream temperatures

• Higher concentrations of pollutants in storm water runoff • Eutrophication • Exceedance of water contact bacteria standards • Potential toxicity to aquatic life • Contaminated sediments • Fish consumption advisories • Higher loads of trash/debris

Source: USDA NRCS

Source: USDA NRCS

• Decline in aquatic insect diversity • Increase in pollutant-tolerant species • Decline in fish diversity • Loss of capacity to support trout/salmon • Declining riparian plant diversity

Source: USDA NRCS

Changes to Stream Hydrology

Physical Alteration of the Stream Corridor

Stream Habitat Degradation

Declining Water Quality

Loss of Aquatic Diversity



Sensitive

Impacted

Non-Supporting

Urban Drainage

Urban Drainage refers to streams that havesubwatersheds with more than 60% IC andwhere the stream corridor has essentially beeneliminated or physically altered to the pointthat it functions merely as a conduit for floodwaters. Water quality indicators areconsistently poor, channels are highly unstableand both stream habitat and aquatic diversityare rated as very poor or are eliminatedaltogether. Thus, the prospects to restoreaquatic diversity in urban drainage areextremely limited, although it may be possibleto achieve significant pollutant reductions.

This chapter presents some quantitativepredictions as to how specific stream indicatorsbehave within the three stream categories ofthe ICM. These predictions help diagnose theseverity of stream impacts, set realistic goalsfor restoration, and may be helpful in thedesign of restoration practices in the streamcorridor. The scientific basis for deriving theICM predictions is documented in Appendix A.

3.1 Changes to Stream3.1 Changes to Stream3.1 Changes to Stream3.1 Changes to Stream3.1 Changes to StreamHydrologyHydrologyHydrologyHydrologyHydrology

The combination of IC, storm drain pipes,compacted soils, and altered flood plainsdramatically changes the hydrology of urbanstreams. During storms, urban watershedsproduce a greater volume of storm water runoffand deliver it more quickly to the streamcompared to rural watersheds. As aconsequence, urban streams have a distincthydrograph, as shown in Figure 13. The urbanstream hydrograph has a much higher andearlier peak discharge rate, compared to ruralor undeveloped streams. In addition, streamflow drops abruptly after storms, and oftensteadily declines during dry weather due to alack of groundwater recharge.

This basic hydrologic response occurs duringevery storm, but the effect is most pronouncedduring smaller, more frequent storms.

Figure 12: Representation of the Impervious Cover Model (ICM)The ICM illustrates the relationship between subwatershed IC and expected stream quality, and

defines three broad urban subwatershed categories–impacted streams, non-supporting streams andurban drainage. The prospects and strategies for restoration are often markedly different for each of

the three subwatershed categories.

WWWWWatershed Imperatershed Imperatershed Imperatershed Imperatershed Impervious Covervious Covervious Covervious Covervious Cover

Stre

am

Qua

lity

Stre

am

Qua

lity

Stre

am

Qua

lity

Stre

am

Qua

lity

Stre

am

Qua

lity

Good

Fair

Poor

10% 25% 40% 60% 100%



Consequently, urban streams experience anincreased frequency and magnitude offlooding. Frequent flash flooding occurs afterintense rain events and often causes chronicflood damage. The increased frequency offlooding from smaller storm events often hasthe greatest impact on streams, as it transportssediments and causes channel erosion.

Another hydrologic impact that may sometimesoccur is a reduction in stream flows afterextended dry weather periods. Urbanheadwater streams can dry out during droughtsdue to a lack of groundwater recharge. In otherurban streams, however, dry weather streamflows may actually increase because ofadditional water flows from irrigation, waterleaks, or sewer exfiltration in thesubwatershed. Much of the tap water supplydelivered in the subwatershed actuallyoriginates in other subwatersheds. Thus, whenresidents or businesses use tap water forirrigation or outdoor washing, some fraction ofthis imported “return” water reaches the stormdrain system and eventually returns to thestream itself. Indeed, urban return water cansubstantially increase dry weather stream flowin arid and semiarid regions.

The severity of changes in urban streamhydrology can be predicted by the ICM, as

described in Table 2. Impacted streams exhibitsubstantial changes in their hydrology,compared to undeveloped or rural streams,with increased runoff, flashier hydrographs andmore frequent bankfull flooding. While thehydrology changes are pronounced, it may stillbe possible to minimize them through acombination of upstream storage retrofitpractices.

Non-supporting streams are much moredominated by urban storm water runoff, withthe frequency and magnitude of floodingincreasing by as much as an order ofmagnitude. It may still be possible to partiallycompensate for changes in stream hydrologythrough a combination of upstream retrofitpractices, but the sheer volume of storm waterrunoff makes it difficult to manage or treat theentire subwatershed. Often, the best that can bedone is to shift hydrologic indicators from non-supporting to the impacted category.

As the name implies, urban drainage iscompletely dominated by storm water runoff,and these streams retain few elements of theiroriginal “natural” hydrology. Indeed, urbandrainage essentially behaves as a conduit forurban storm water. Given the prodigiousvolume of storm water produced and thelimited space available to store it, it is often

Figure 13: Comparison of Urban and Rural HydrographsA hydrograph shows the rate of flow in a stream over time after a rainfall event. The hydrograph of an urban

subwatershed (dashed line) is compared to a rural subwatershed (solid line). Note the higher and earlier peakdischarge that occurs in the urban subwatershed.

Source: Schueler, 1987



impossible to meaningfully improvehydrological indicators for urban drainage. Itmay still be possible to prevent flood damagefrom extreme storms in urban drainage, butthese efforts may require significant alterationsto the existing stream corridor.

3.2 Physical Alteration of the3.2 Physical Alteration of the3.2 Physical Alteration of the3.2 Physical Alteration of the3.2 Physical Alteration of theStream CorridorStream CorridorStream CorridorStream CorridorStream Corridor

Urban stream corridors are profoundly alteredby land development, and the severity of thealteration can be generally predicted based onsubwatershed IC. Major alterations includestorm drain enclosure, culverts, flood plainencroachment, clearing and mowing, road andsewer crossings, and various engineering“improvements” designed to fix the stream(and its flood waters) in the desired place.

Cumulatively, these improvements can greatlyreduce the length of the stream channelnetwork within urban subwatersheds, with adisproportionate loss of smaller headwaterstreams that are enclosed by pipes, channelizedor culverted. Dams, pipelines, bridges andother stream crossings also create manypotential fish barriers that prevent resident and/or anadromous fish from moving freelythrough the stream network. Consequently,spawning success often declines sharply inurban streams.

Forest or natural cover along the streamcorridor is frequently lost after subwatersheddevelopment or is confined to a narrow strip.

In many cases, the forest buffers that remainare cleared and managed as turf. Theprogressive reduction in the continuity ofnatural buffers along the stream corridor hasmany detrimental consequences to streamecology and aesthetics. The degree of forestbuffer loss in the urban stream corridor isexemplified by the Hospital Branchsubwatershed near Lewisburg, TN (Figure 14).While Hospital Branch has only 20% IC, lessthan half of its stream network has an adequateforest buffer. The quality of the remainingforest buffer in the urban stream corridor isoften degraded by invasive plants, dumpingand encroachment.

The degree of physical alteration of the urbanstream corridor can be forecast in the contextof the ICM, as shown in Table 3. Impactedstreams often experience moderate interruptionof the stream corridor, some loss of headwaterstream channels and moderate loss of forestbuffers. Because the stream corridor alterationsare relatively modest in most impactedsubwatersheds, they can often be directlyrestored using practices such as fish barrierremoval, stream daylighting or riparianreforestation.

Stream corridors of non-supporting streamsexperience major alteration, with significantloss of headwater streams and forest buffers,severe flood plain encroachment, and frequentstream interruption. The alterations may be lesssevere, however, if a community hashistorically regulated its flood plains orreserved land in the stream valleys for parks.

Table 2: Hydrologic Predictions According to the ICM

ICM Stream Classification Stream Hydrology Indicator

Impacted Non-Supporting Urban Drainage

Storm Water Runoff as a Fraction of Annual Rainfalla 10 to 30 % 25 to 60 % 60 to 90 %

Ratio of Peak Discharge 100 Year Stormb 1.1 to 1.5 1.5 to 2 2 to 3

Frequency of Bankfull Flood Eventsc 1.5 to 3 per year 3 to 7 per year 7 to 10 per year

Notes: a) Storm water runoff in undeveloped streams ranges from 2 to 5%. b) The ratio for undeveloped streams for the 100-year storm is 1.0. Ratios are often much greater for storm events of lower return frequency. c) Pre-development bankfull flood frequency is about 0.5 per year, or about one bankfull flood every two years.



Table 3: ICM Predictions Concerning Physical Alteration of the Urban Stream Corridor

ICM Stream Classification Stream Corridor Alteration Factor Impacted Non-Supporting Urban Drainage

Fraction of Original Stream Network Remaining a

60 to 90%

25 to 60%

10 to 30%

Fraction of Riparian Forest Buffer Intact b 50 to 70% 30 to 60% less than 30%

Stream Crossings c 1 to 2 per stream mile 2 to 10 per stream mile No stream to cross Notes: a) Undeveloped streams typically have 90 to 100% of original stream network remaining. b) Undeveloped streams normally have 80 to 100% of riparian forest buffer intact. c) Rural streams usually have less than one crossing per stream mile.

Given the extent of alterations in non-supporting streams, it is often difficult to fullyrestore the entire stream corridor, although it isoften possible to find some individual streamreaches within the subwatershed where thestream corridor can be repaired or restored.

Subwatersheds classified as urban drainageare essentially conduits for storm water andpossess a stream corridor with few natural

features. Typically, most first and second orderstreams are enclosed or channelized; much ofthe stream corridor is eliminated or confined toa narrow strip; and forest buffers are few andfar between. The stream corridor that doesremain is often intensively managed forrecreation or flood control. Thus, the prospectsto restore the stream corridor are limited inurban drainage subwatersheds. Someopportunities may exist to mitigate flooding

Figure 14: Loss of Riparian Forest Continuity in an Impacted SubwatershedThe loss of forest buffers along the stream network is clearly evident in this aerial photo of an

impacted subwatershed in Tennessee. Red shading shows where the forest buffer has been clearedfrom the riparian corridor, and is an index of riparian forest continuity.

Inadequate Buffer

Stream



problems, restore a natural area remnant orcreate a greenway linking the remainingfragments of intact stream corridor. There mayalso be selected opportunities to restore higherorder streams and rivers that escapedenclosure.

3.3 Degradation of Stream3.3 Degradation of Stream3.3 Degradation of Stream3.3 Degradation of Stream3.3 Degradation of StreamHabitatHabitatHabitatHabitatHabitat

The increased magnitude and frequency ofstorm water flows give urban streams morepower to transport sediment and cause channelerosion. Most urban streams respond byenlarging their channel cross-section toaccommodate the increased flows. Channelenlargement occurs through a combination ofwidening or down-cutting, depending on thestream type. The cross-section of the currentchannel can be two to 10 times larger than thepre-development channel, although the fulladjustment process may take many decades tocomplete. Consequently, channel erosion issevere in urban streams, and causes extensivedamage to both public infrastructure andprivate property.

The active phase of urban channel erosiongreatly increases the sediment supply to urbanstreams. Urban streams commonly transporttwo to 10 times more sediment than ruralstreams. As this sediment moves through thestream, it exerts a strong influence on thestreambed, causing many alternating cycles ofsediment deposition and erosion.

When increased sediment transport iscombined with active channel erosion andfrequent flooding, it isn’t surprising that manyhabitat features are simplified or eliminated inurban streams (Figure 15). Typically, thenormal low-flow channel becomes extremelyshallow and variable, and pool and rifflestructure is lost. Individual habitat elementssuch as large woody debris, pools, channelsinuosity, meanders, and undercut banks aresharply diminished. The materials of thestreambed turn over frequently, and finesediments become embedded within coarser-grained bed materials. As a result, the highlyunstable and embedded streambed becomesless suitable for fish spawning.

Stream habitat is typically measured byexamining a composite of individual habitatmetrics thought to contribute to habitat quality.Based on these assessments, most urbanstreams are consistently ranked as having“poor” to “fair” stream habitat. Few urbanstreams are ever classified as having “good” or“excellent” habitat ratings.

Finally, urban streams tend to have warmersummer temperatures than undevelopedstreams, with mean temperatures increasing bytwo to 10 degrees Fahrenheit. Much of thestream warming is caused by the heat islandeffect of IC, but can be intensified byimpoundments and the loss of streamside forestcover. In many regions of the country, urbanstream warming makes it difficult to supporttrout, salmon and other cold-water adaptedspecies.

The ICM predicts the nature and extent ofhabitat degradation, which can help craftrealistic strategies to restore or repair urbanstreams (Table 4). Impacted streams typicallypossess “fair” habitat, although “good” habitatconditions may be encountered at the lowerrange of IC. The potential to restore manyhabitat elements in impacted streams is oftengood, if the stream corridor remains intact andupstream retrofits are built. Under theseconditions, it may even be possible tosystematically restore habitat throughout thestream network of an impacted subwatershed.

Non-supporting subwatersheds consistentlyexperience severe erosion, extensive habitatdegradation and frequent interruption of theremaining stream network. For these reasons,many practitioners doubt that full ecologicalrestoration is possible within non-supportingstreams (Konrad, 2003). Still, importantstructural and functional stream elements canbe repaired, particularly if upstream retrofitscreate more stable hydrological conditions.Consequently, “restoration” within this class ofstreams involves practices that repair a specificstream problem at a defined point or reachwithin the stream network, which may or maynot have associated ecological benefits.Common stream repairs include stabilizingeroding streambanks, removing fish barriers,



Table 4: Stream Habitat Predictions According to the ICM

ICM Stream Classification Stream Habitat

Indicator Impacted Non-Supporting Urban Drainage Ultimate Channel Enlargement Ratio a

1.5 to 2.5 times larger

2.5 to 6 times larger

6 to 12 times larger

Sediment Yieldb 2 to 5 times greater

5 to 10 times greater possibly lower

Typical Stream Habitat Score c fair, but variable consistently poor poor, often absent Presence of Large Woody Debris d

2 to 3 pieces per 100 feet scarce absent

Increased Summer Stream Temperatures e

2 to 4 degrees F

4 to 8 degrees F

8 + degrees F

Notes a) Ultimate channel cross-section compared to pre-development cross-section. b) Compared to stable rural stream. c) As computed by EPA Rapid Bioassessment Index or QHI. d) Forested streams have 5 to 15 pieces of LWD per 100 feet of stream. e) Compared to shaded rural stream.

Figure 15: Contrast in Habitat Features Between Rural and Non-Supporting StreamsThese photos compare typical habitat features in urban and rural streams, with respect to bank

stability, sediment deposition, channel enlargement, and riparian cover. Also, note the difference inthe depth and wetted perimeter of the baseflow channel between the two streams.

A. Reference Stream

B. Urban Stream

GGoooodd RRiippaarriiaann BBuuffffeerr

Stable Banks

MMiinnoorr SSeeddiimmeenntt

DDeeppoossiittiioonn

NNoo EEvviiddeennccee ooff CChhaannnneell WWiiddeenniinngg

UUnnssttaabbllee BBaannkkss SSeeddiimmeenntt

Deposition

Evidence of Channel Widening

Embeddedness



preventing channel incision or recreating in-stream habitat.

Subwatersheds classified as urban drainagehave extremely poor stream habitat in the fewplaces where it has not been physicallyeliminated. Consequently, the prospects forrestoring the structure and function of theurban drainage channels are very poor,although some individual reaches may showsome restoration potential. In addition, habitatimprovements or stream repairs may still bepossible on larger streams and small rivers thatmay have escaped significant alteration.

3.4 Decline in W3.4 Decline in W3.4 Decline in W3.4 Decline in W3.4 Decline in Water Qualityater Qualityater Qualityater Qualityater Quality

Just about any pollutant deposited from theatmosphere or generated within a subwatershedis likely to be washed off in urban storm waterrunoff (Figure 16). Consequently, storm waterrunoff contains a wide range of pollutants thatcan degrade local or downstream water quality.A recent summary of national medianconcentrations for more than 20 pollutantsfrequently detected in storm water runoff isprovided in Appendix A. Pollutantconcentrations tend to vary with each stormevent, and may also vary based on theprevailing land use, region of the country, andtype of precipitation. In general, however, theunit area pollutant load delivered to a streamalways increases in direct proportion tosubwatershed IC.

Pollutant reduction is usually a major goal ofmost watershed restoration efforts. The basicstrategy is to determine which pollutants arecausing the water quality problems of greatestconcern, isolate their major sources in thesubwatershed, and then apply a combination ofrestoration practices to treat runoff to reducethese pollutant levels.

A comprehensive review of the concentrations,sources and water quality impacts of 10 majorstorm water pollutants found in urban stormwater can be found in CWP, 2003. Thesepollutants include sediment, nutrients, tracemetals, hydrocarbons, bacteria, organic carbon,pesticides, deicers, and trash and debris.

The severity of water quality problems in urbanstreams can be reliably predicted withknowledge of subwatershed IC. From theperspective of the ICM, it is important toexamine five common water quality problems:eutrophication, exceedance of bacteriastandards, aquatic life toxicity, sediment andfish tissue contamination, and trash and debrisloads (Table 5).

EutrophicationEutrophicationEutrophicationEutrophicationEutrophication

High levels of phosphorus and nitrogen inurban storm water runoff can causeeutrophication in streams and contribute toalgal blooms in downstream lakes andestuaries. The annual nutrient load produced byurban subwatersheds can be as much as sixtimes higher than rural ones, making it difficultto completely reverse the symptoms ofeutrophication.

Impacted subwatersheds generatecomparatively modest nutrient loads, and itmay be possible to reduce these loads to ruralbackground levels through widespreadimplementation of restoration practices.Achieving nutrient reduction goals in non-supporting subwatersheds is more problematic.The crux of the problem is that nutrient loads inthese subwatersheds are two to four timesgreater than rural subwatersheds, yet current

Figure 16: Nine Major Pollutant Categories Found inUrban Storm Water Runoff



restoration practices can generally only reducenutrient load by about 40 to 60% (evenassuming that the subwatershed is fully treatedwith retrofits and source controls).Nevertheless, nutrient reduction efforts maystill be warranted in non-supportingsubwatersheds as one part of a comprehensivewatershed-wide nutrient reduction strategy.

The disparity between the nutrient loadproduced and the capacity to reduce it is evengreater in subwatersheds classified as urbandrainage. Given the intensity of developmentin urban drainage subwatersheds, it is often achallenge to find enough feasible retrofit sitesto get full treatment of all nutrient sources.Still, nutrient reduction may still make sense inan urban drainage subwatershed if it cost-effectively contributes to a watershed-widereduction strategy.

Bacterial ContaminationBacterial ContaminationBacterial ContaminationBacterial ContaminationBacterial Contamination

Fecal coliform bacteria levels found in stormwater runoff routinely exceed water qualitystandards, thereby limiting or preventing watercontact recreation, shellfish harvesting or

Table 5: Water Quality Predictions According to the ICM

ICM Stream Classification Water Quality Indicator Impacted Non-Supporting Urban Drainage

Annual Nutrient Load a

1 to 2 times higher than rural background



Violations of Bacteria Standards b

Frequent violations during wet weather

Continuous violations during wet weather;

Episodic violations during dry weather

Continuous violations during wet weather,

frequent violations during dry weather

Aquatic Life Toxicity c Acute toxicity rare

Moderate potential for acute toxicity during

some storms and spills

High potential for acute toxicity during dry and

wet weather

Contaminated Sediments

Sediments enriched but not contaminated

Sediment contamination likely, potential risk of

bioaccumulation

Contamination should be presumed

Fish Advisories d Rare Potential risk of bioaccumulation Should be presumed

Trash and Debris e 1 to 2 tons per square mile

2 to 5 tons per square mile

5 to 10 tons per square mile

Notes a) Annual load of phosphorus or nitrogen produced by a rural subwatershed. b) Rural stream might violate standards during 10 to 20% of storms. c) Acute toxicity would be very rare in a rural stream. d) Enrichment in comparison to sediment quality of rural stream. e) Based on trash loading estimates from various CA, MD, and NY trash studies and TMDLs.

swimming in urban waters during and afterstorm events. Bacteria levels can sometimesviolate water quality standards during dryweather periods as a result of sewage leaks,overflows or illicit discharges. The degree towhich bacteria impairs designated uses inurban waters is a direct function of IC and canbe interpreted in the light of the ICM(Schueler, 1999).

Streams within impacted subwatersheds willfrequently violate bacteria standards duringsome storm events, but usually support watercontact recreation during dry weather periods,particularly at the lower end of the IC range.Often, impacted streams can reliably meetstandards when storm water retrofit andbacterial source controls are applied to thesubwatershed.

Streams in non-supporting subwatershedscontinuously violate standards during wetweather conditions unless favorable dilution ormixing conditions are present. Non-supportingstreams may also episodically violate bacteriastandards during dry weather periods, as aresult of sewage leaks and overflows. Bacteriastandards can seldom be attained in non-



supporting streams during wet weatherconditions even with extensive subwatershedtreatment. The main reason is that bacteriaconcentrations are so high that they wouldrequire a 99% removal rate in order to achievestandards. Such a high level of treatmentcannot be achieved with current restorationpractices (Schueler, 1999). However, ifbacteria sources are found and eliminated fromthe sewer and storm drain network, standardsmay be achievable during dry weatherconditions.

Subwatersheds that are classified as urbandrainage continuously violate bacteriastandards during wet weather conditions andfrequently violate them during dry weather, aswell. Given the sheer number and diversity ofbacteria sources, it is not realistic to expectcompliance with bacteria standards in urbandrainage “streams.” However, bacteria sourcecontrols may still be warranted if theycontribute to a larger watershed bacteria-reduction strategy.

Aquatic Life TAquatic Life TAquatic Life TAquatic Life TAquatic Life Toxicityoxicityoxicityoxicityoxicity

Storm water runoff contains concentrations ofcopper, chlorine, zinc, cadmium, lead,hydrocarbons, and deicers that can potentiallybe toxic to aquatic life in urban streams. Inaddition, numerous pesticides have beendetected during storm flow and dry weatherflow within urban streams, including severalknown to cause mortality in aquatic life. Othertoxins may enter urban streams as a result ofspills, accidents, leaks and illicit dischargesfrom storm water hotspots, which producehigher levels of storm water pollution and/orpresent a higher risk for spills, leaks and illicitdischarges. In general, the number anddiversity of storm water hotspots increase withthe intensity of subwatershed development.Consequently, the risk of potential toxicity toaquatic life can be interpreted within thecontext of the ICM.

Most scientists agree that acute toxicity toaquatic life is rare in impacted streams,although others suggest that some pollutantsmight cause chronic toxicity. Pollutant levels inurban storm water are typically below the

thresholds for acute toxicity, although they mayexceed standards for brief periods of time. Thegreatest risk of aquatic life toxicity in impactedstreams is from spills, accidents anddischarges. This risk can be sharply reduced ifpollution prevention practices are implementedat storm water hotspots in impactedsubwatersheds.

Non-supporting subwatersheds exhibitmoderate potential for acute toxicity duringsome storms and spill events. The toxins ofgreatest concern will often vary in non-supporting subwatersheds, and depend on theprevailing mix of land use and hotspots. Therisk of potential toxicity to aquatic life in non-supporting streams can be reduced if retrofitand pollution prevention practices are widelyapplied across the subwatershed. The issue oftoxicity in urban drainage is often moot, sinceother stressors have already diminished thediversity of aquatic life (i.e., sensitive fish andinsect species are often eliminated). Pollutionprevention practices and retrofits may bewarranted in urban drainage subwatersheds ifthey reduce toxin loads to downstream aquaticecosystems.

Sediment ContaminationSediment ContaminationSediment ContaminationSediment ContaminationSediment Contamination

Many pollutants are attached to sedimentsborne in storm water runoff, which areeventually deposited in slow-moving waterssuch as lakes, rivers, estuaries and wetlands.Urban sediments have a diagnostic signature ofcontamination, with enriched levels of copper,cadmium, lead, mercury, zinc, organic carbon,hydrocarbons and pesticides. In addition, long-banned compounds such as DDT, dieldrin, andPCBs are often detected in urban sediments.

The effect of sediment contamination onaquatic life is poorly documented, but clearevidence exists that metals, pesticides andhydrocarbons bioaccumulate in larger fish andother aquatic life in urban streams. Forexample, the USGS (2001) found that 100% offish sampled in urban streams had detectablelevels of pesticide in their tissues. Even moretroubling was the finding that 20% of the fishtissue samples exceeded recommended levelsfor fish-eating wildlife (such as raccoons,



kingfishers, ospreys and eagles). Pollutantlevels in fish tissue may sometimes exceedaction levels set to protect human health inhighly urban subwatersheds. When these occur,health authorities issue advisories to prevent orrestrict fish consumption from local waters.

The severity of sediment contamination can beevaluated within the context of the ICM.Sediment contamination is usually not a majorproblem for impacted subwatersheds, althoughdeposited sediments will usually contain higherlevels of trace metals and hydrocarbons thanwould be found in a rural stream. The potentialfor sediment contamination and subsequentbioaccumulation in fish and other aquatic lifeis much greater in non-supportingsubwatersheds. The risk is greatest for lakes,coves and waterfronts that are small in relationto the area of their contributing non-supportingsubwatershed.

In general, it should be presumed that bottomsediments from urban drainage subwatershedswill be contaminated with some pollutants, andthat these may bioaccumulate within whateverremains of the fish community. Consequently,human consumption of fish from urbandrainage subwatersheds should be avoided.

Trash and Debris Large quantities of litter,trash and debris wash through the storm drainsystem into streams and receiving waters.Often, the problem is exacerbated by illegaldumping. While trash and debris are anunsightly annoyance in other settings, they area major problem in urban subwatersheds. Theprodigious loads of trash and debris generatedby urban subwatersheds can diminish thescenic character of urban waters andwaterfronts, interfere with designated usessuch as swimming or boating, and severelydetract from public attitudes about streamquality.

While trash is often noticed, it is seldommeasured in urban streams. Recent preliminaryestimates of trash generation rates for urbanstreams range from one to 10 tons of trash anddebris per square mile of urban subwatershed(see Appendix A). Trash and debris loadsappear to be related to subwatershed IC. Within

the context of the ICM, the followingpredictions can be made with respect to trashand debris and its management.

Trash is noticeable in impacted subwatersheds,and often concentrates in debris jams andbackwaters. However, generation rates arerelatively modest, particularly if the impactedsubwatershed is primarily residential. Cleanupsand education can make a real difference in theappearance of impacted streams, as long asthey are frequently repeated.

Trash can become a moderate to severeproblem within non-supporting and urbandrainage subwatersheds. The higher rate oftrash generation means that creeks, shorelines,and waterfronts will receive a significant loadof trash and debris after every major storm.Even regular stream cleanups may not keeppace with this increased supply. Additionalmeasures such as booms, catch basin cleanouts, litter enforcement, storm drain stenciling,dumpster management or the operation of trashskimmers may be needed to control the trashproblem.

3.5 L3.5 L3.5 L3.5 L3.5 Loss of Aquatic Diversityoss of Aquatic Diversityoss of Aquatic Diversityoss of Aquatic Diversityoss of Aquatic Diversity

The decline in physical, hydrologic and waterquality indicators collectively diminishes thequality and quantity of available habitat inurban steams. As a result, urban streamsexperience reduced aquatic diversity, a shifttoward more pollution-tolerant species, and aprogressive loss of ecosystem structure andfunction (CWP, 2003).

This trend is exemplified by aquatic insects,which often form the base of the stream foodchain in many streams in North America. Ingeneral, aquatic insect diversity declines assubwatershed IC increases. A typical exampleof this relationship is provided in Figure 17,which compares aquatic insect diversity scoresfor a large number of subwatersheds withdifferent IC in suburban Northern Virginia.While some scatter is always seen in such data,the trend toward reduced aquatic insectdiversity with progressively greater IC isclearly evident.



Figure 17: Relationship Between Subwatershed IC and Aquatic Insect DiversityThis is one of many studies that shows the decline in aquatic insect diversity as a function of

subwatershed IC (Fairfax County, 2000). While there is always some variability in aquaticinsect data, note how diversity scores rarely exceed 60% B-IBI or “fair” once subwatershed IC

exceeds 20%.

Under current patterns of development, urbanstreams lose their potential to have “good” or“excellent” aquatic insect diversity at about20% subwatershed IC, and lose the potential toachieve “fair” diversity scores at about 30%subwatershed IC. This basic pattern in aquaticinsect diversity has been reinforced by morethan 20 urban stream studies (CWP, 2003).

Other researchers have noted that habitat- orpollution-sensitive species are eliminated fromthe aquatic insect community in highly urbanwatersheds. The most common method used toassess this change is the EPT index, whichlooks at the proportion of sensitive stonefly,mayfly and caddisfly species found in theaquatic insect community (Table 6).

A similar decline is also observed for fishdiversity in urban streams. Sharp drops in fishdiversity scores are universally reported forurban streams, with the best index scoresranging from “fair” to “very poor.” The healthof the fish community is also diminished, withlesions and bioaccumulation commonly

reported. The fish community in urban streamsalso tends to be dominated by pollution-tolerant or non-native species. Sensitive fishspecies that require cold water or a cleanstream bed usually disappear as subwatershedIC increases.

Consequently, it is difficult to maintain a self-sustaining trout or salmon population in manyurban streams. Likewise, poor stream bedquality and frequent stream interruption makeurban streams a poor spawning environmentfor anadromous fish that move from estuariesor the oceans to spawn.

Although urban stream ecology remains a veryyoung science, researchers have discoveredthat important functional elements of streamecosystems are altered by subwatersheddevelopment (Paul and Meyer, 2001; Palmer etal., 2002; Meyer and Couch, 2001). Forexample, stream researchers have found thatin-stream processes such as leaf pack decay,nutrient uptake, retention time and carbonprocessing occur at different rates in urban



streams compared to rural or undevelopedones. It is too early to tell how these changes inecosystem function will influence the prospectsfor urban stream restoration.

An important but frequently overlooked aspectof stream corridor biodiversity is thesimplification of plant diversity in the floodplains and wetlands. Both plant communitiessuffer from filling and encroachment, andremaining fragments continue to be disturbedby increased water fluctuations, falling watertables, exotic plants, deer browsing and humandisturbance. Consequently, wetland and floodplain plant communities often experiencesignificant changes in species composition,with increased invasive or exotic species,declining regeneration of native species, andlongitudinal shifts in species along the streamcorridor (Brush and Zipperer, 2002; Groffmanet al. 2003).

The loss of aquatic diversity in the urbanstream corridor can be interpreted in the lightof the ICM (Table 6). As with other indicators,impacted streams experience a fairly moderatedecline in aquatic diversity, with diversityscores consistently ranking as “fair” to “good.”Thus, prospects for partial recovery are good ifrestoration practices can be applied

comprehensively to both the stream corridorand upland areas of the subwatershed. It mayeven be possible to partially restore a trout,salmon or anadromous fishery, particularly atthe low end of the IC range of impactedstreams.

Full restoration of aquatic diversity in non-supporting streams is probably an elusive goal,given the many different stressors affecting thestream and its flood plain. Most diversityindicators are solidly in the “poor” range fornon-supporting streams. If restoration practicesare comprehensively applied across a non-supporting subwatershed, it might be possibleto shift the communities into the “fair” range,but it is doubtful whether “good” or“excellent” diversity can ever be attained.Improved diversity is possible, however, ifsuccess is defined in the context of a “good”urban stream instead of an unattainable highquality undeveloped stream. For example,while it may be impossible to support a self-sustaining trout population in a non-supportingstream, it may be possible to support a “put andtake” trout fishery with annual stocking.Similarly, it may still make sense to removefish barriers in non-supporting streams, even ifactual spawning success will vary greatly fromyear to year.

Table 6: Predictions on Aquatic Diversity According to the ICM

ICM Stream Classification Aquatic Diversity Indicator Impacted Non-Supporting Urban Drainage

Aquatic Insect Diversity a fair to good poor very poor

EPT Taxa b 40 to 70% 20 to 50% 0 to 20%

Fish Diversity c fair to good poor very poor

Trout or Salmon d limited potential temporary use only no potential Riparian Plant Diversity

stressed, with reduced native plant diversity

simplified community with many exotic species

isolated remnants; dominated by exotics

Notes a) As measured by Benthic Index of Biotic Integrity (B-IBI). Scores for rural streams normally range from “good” to “very good.” b) Aquatic insect metric that looks at sensitive stonefly, caddisfly and mayfly species; values shown are percent of score for undeveloped reference stream or a “put and take” fishery c) As measured by Fish Index of Biotic Integrity (F-IBI). Scores for rural streams typically range from “good” to “excellent.” d) Ability to maintain a self-reproducing population. e) As compared to flood plain forest or wetlands plant community adjacent to rural stream.



Subwatersheds classified as urban drainagehave “poor” to “very poor” aquatic diversity inthe portions of the stream network that stillsupport stream habitat. As noted earlier, urbandrainage is frequently interrupted, which makesnatural recolonization difficult or impossible.Consequently, prospects for restoring muchaquatic diversity in urban drainage is extremelylimited, although some individual streamreaches may show modest restoration potential.The best candidates are larger streams andsmall rivers that may have escaped significantalteration and natural area remnants along thestream corridor.

3.6 Summar3.6 Summar3.6 Summar3.6 Summar3.6 Summaryyyyy

The ICM sets benchmarks that define streamquality expectations for each of the three urbanstream categories. As such, the ICM cangenerally predict the severity of streamimpacts, and set realistic goals forsubwatershed restoration. It bears repeatingthat the ICM is a guide and not a guarantee.Some urban streams will depart from theseexpectations, and these outliers are often ofconsiderable interest when it comes torestoration design. The next chapter reviewsthe full range of restoration practices that canbe used to compensate for the impact ofsubwatershed development.




Chapter 4: The Range of Subwatershed Restoration Practices

Chapter 4: The RChapter 4: The RChapter 4: The RChapter 4: The RChapter 4: The Range of Subwatershedange of Subwatershedange of Subwatershedange of Subwatershedange of SubwatershedRRRRRestoration Pestoration Pestoration Pestoration Pestoration Practicesracticesracticesracticesractices

The term “restoration practice” is defined asthe application of structural or non-structuraltechniques in urban subwatersheds to improvestream health, as measured by improvements inphysical, hydrological, chemical, ecological orsocial indicators. At least 130 differenttechniques can potentially be used to restoreurban subwatersheds. These restorationpractices can be broadly classified into sevenmajor groups, which are reviewed in thischapter (Figure 18):

1. Storm Water Retrofit Practices2. Stream Repair Practices3. Riparian Management Practices4. Discharge Prevention Practices5. Watershed Forestry Practices6. Pollution Source Control Practices7. Municipal Practices and Programs

The choice of which combination of practicesto apply depends on your restoration goals,along with the restoration potential anddevelopment intensity within yoursubwatershed. In general, the first four types ofrestoration practices are applied to theremaining stream corridor. The remaining threerestoration practices are usually applied toupland areas in the subwatershed, althoughsome on-site storm water retrofits can also beinstalled in upland areas.

This chapter describes each major group ofrestoration practices, briefly reviews thespecific strategies and techniques forimplementing them, and discusses howrestoration practices can meet subwatershedrestoration goals.

4.1 Storm W4.1 Storm W4.1 Storm W4.1 Storm W4.1 Storm Water Rater Rater Rater Rater RetrofitetrofitetrofitetrofitetrofitPPPPPracticesracticesracticesracticesractices

Storm water retrofits are structural practicesinstalled within the stream corridor or uplandareas to capture and treat storm water runoffbefore it is delivered to the stream. Stormwater retrofits are the primary practice forrestoring subwatersheds, since they can removeand/or treat storm water pollutants, minimizechannel erosion, and help restore streamhydrology. Retrofits can be further classifiedby the subwatershed area they treat. Storageretrofits, such as ponds, wetlands, filtering andinfiltration practices, can typically treatsubwatershed areas ranging from five to 1,000acres.

On-site retrofits capture runoff from individualsource areas, such as rooftops, parking lots andstreet sections. Residential on-site retrofits aredesigned to treat areas as small as a fewhundred square feet, whereas nonresidentialretrofits normally serve areas up to two acres insize. Manual 3 provides extensive guidance on17 different retrofit techniques that can beapplied in urban subwatersheds; a summary listis provided in Appendix B.

Storage RStorage RStorage RStorage RStorage Retrofitsetrofitsetrofitsetrofitsetrofits

A typical example of a storage retrofit is thepond/wetland system constructed within anolder detention pond shown in Figure 19. Thisretrofit was designed to remove pollutants fromstorm water runoff, reduce downstreamchannel erosion, and provide local wildlifehabitat. As the name implies, storage retrofitsmay require several acre-feet of storage toeffectively perform their restoration function.Therefore, the best sites for storage retrofits arefound within existing detention ponds, aboveroadway embankments and culverts, withinhighway rights-of-way, within large parking



Pollution Source Control

Figure 18: Seven Groups of Practices Used to Restore Urban Watersheds

Restoration plans are about choosing and applying the right combination of these seven practices in a

subwatershed that can meet restoration goals.

• Storage retrofits • On-site non-residential retrofits • On-site residential retrofits

• Stream clean-ups • Stream repair practices • Comprehensive restoration practices

• Site preparation • Active reforestation • Park or greenway plantings • Natural regeneration • Riparian wetland restoration

Finding, fixing or preventing: • Illicit sewage connections • Commercial and industrial illicit

connections • Failing sewage lines • Industrial and transport spills

Source: USDA

• Land reclamation • Upland revegetation/reforestation • Management of natural area

remnants

Storm Water Retrofits

Stream Restoration

Riparian Management

Discharge Prevention

Pervious Area Restoration

Municipal Practices

Source: USDA NRCS

lots, and at golf courses. New storage retrofitscan also be constructed at existing storm wateroutfalls, if enough adjacent land is available toprovide the required storage.

Many storage retrofits must be constructedwithin a subwatershed to meet restoration ortreatment goals. The process of finding andevaluating candidate sites for storage retrofitsis known as a “retrofit inventory.” In general,site constraints and land availability make itimpossible to obtain full treatment with storageretrofits across a subwatershed, but it is oftenpossible to find enough storage to reducepollutant loads to meet many subwatershedgoals.

On-siteOn-siteOn-siteOn-siteOn-siteNonresidentialNonresidentialNonresidentialNonresidentialNonresidentialRRRRRetrofitsetrofitsetrofitsetrofitsetrofits

Commercial, industrial and institutional sitescan also provide opportunities to treat stormwater runoff. The objective of nonresidentialon-site retrofits is to capture and treat stormwater from larger rooftops, parking lots, andother source areas. Common examples includethe construction of bioretention islands withinexisting parking lots, green roofs, and stormwater planters to treat rooftop runoff. Often,on-site nonresidential retrofits are oftencombined with storage retrofits to achievecomprehensive treatment across asubwatershed.

• Street and storm drain practices• Best practices for development/

redevelopment• Stewardship of public land• Municipal stewardship programs• Watershed education and enforcement

• Residential source control• Hotspot source control



4.2 Stream Repair Practices4.2 Stream Repair Practices4.2 Stream Repair Practices4.2 Stream Repair Practices4.2 Stream Repair Practices

Stream repair practices include a large groupof techniques used to enhance the appearance,structure or function of urban streams. Thesepractices range from simple stream cleanupsand basic stream repairs to extremelysophisticated stream restoration techniques.Stream repair practices are often combinedwith storm water retrofits and riparianmanagement practices to meet subwatershedrestoration goals. Manual 4 provides detailedguidance on 33 different stream repairtechniques that can be applied in urbansubwatersheds; a summary list is provided inAppendix B.

These techniques involve regular pickup anddisposal of trash, debris, litter, and rubble fromthe stream or its corridor, usually withvolunteer help. While stream cleanups areoften cosmetic and temporary, they areextremely effective tools for involving andeducating the public about urban streamdegradation. In addition, public attitudestoward urban creeks are often influenced bythe presence or absence of trash and debris.Well-organized and frequent stream cleanupprograms can remove impressive quantities oftrash and debris from the stream corridor, thuspreventing its movement to downstreamwaters.

On-siteOn-siteOn-siteOn-siteOn-siteRRRRResidentialesidentialesidentialesidentialesidentialRRRRRetrofitsetrofitsetrofitsetrofitsetrofits

Rain barrels and rain gardens are commonexamples of on-site residential retrofitpractices. On-site retrofits are typicallyinstalled on individual homes or yards to storeor infiltrate runoff from rooftops, driveways oryards. On-site retrofits promote infiltration,which can reduce storm water runoff, treatstorm water pollutants at their source, andincrease groundwater recharge. Because eachindividual on-site retrofit treats such a smallarea, dozens or hundreds are needed to make ameasurable difference at the subwatershedlevel. Consequently, widespread homeownerimplementation of on-site retrofits requirestargeted education, technical assistance andfinancial subsidies. On-site retrofits are oftencombined with storage retrofits to increase theextent of subwatershed treatment.

Figure 19: Example of a Storage Retrofit PondThe top photo shows an old flood detention pond

that was converted into a shallow marsh pondsystem to remove pollutants and protect

downstream banks (bottom photo). This storageretrofit, known as Rolling Stone, was constructed in

the late 1980s and treats about 75 acres ofupstream drainage.

StreamStreamStreamStreamStream

CleanupsCleanupsCleanupsCleanupsCleanups



Figure 20: The Seven Basic Types of Stream Repair TechniquesStream repair techniques are designed to fix a problem at a defined point along the stream.

They can be organized according to the seven basic problems they attempt to fix : hard banktechniques to stabilize eroding banks (Panel A), soft or deformable bank stabilization

techniques (Panel B), grade controls to stop channel incision (Panel C), flow deflectors toconcentrate the low flow channel (Panel D), techniques to enhance stream habitat features(Panel E), storm water flow diversions (Panel F) and techniques to remove or mitigate fish

barriers (Panel G).



salmon population or enhancing fish diversity,meeting this goal requires integrating streamrestoration efforts with other restorationpractices in the stream corridor andsubwatershed. An excellent example of acomprehensive approach to stream restorationis Wheaton Branch in Montgomery County,Maryland (Figure 21).

4.3 Riparian 4.3 Riparian 4.3 Riparian 4.3 Riparian 4.3 Riparian ManagementManagementManagementManagementManagement

Riparian management practices involve eightbasic techniques to restore the quality of forestsand wetlands within the remaining streamcorridor. The overall goal of riparianmanagement is to improve the continuity ofstreamside vegetation to maximize the manybenefits that buffers provide (e.g., pollutantremoval, shading, large woody debris, etc.).Given that urban stream corridors are heavilyused and have multiple owners, manyindividual riparian management projects mayneed to be linked together to create a betterriparian zone. Each riparian managementproject must be designed to address the uniquestresses and disturbances that occur within theurban stream corridor, and maximize stormwater infiltration and subsequent pollutantremoval. Manual 5 offers detailed guidance oneight riparian management techniques torevegetate the stream corridor; a summary listis provided in Appendix B.

Site PSite PSite PSite PSite Preparationreparationreparationreparationreparation

While there may be many potential reforestationsites in the urban stream corridor, they are oftenhighly impacted by dumping, soil compaction,hill-slope erosion, mowing, invasive plants andother disturbances. Site preparation is usuallyneeded to make a riparian site suitable forsuccessful revegetation or reforestation. Sitepreparation techniques include removal of trashand rubble, control of invasive plant species,restoration of urban soils, control of hill-slopeerosion, and the capture and distribution ofstorm water evenly across the riparian zone.

Stream RStream RStream RStream RStream Repair Tepair Tepair Tepair Tepair Techniquesechniquesechniquesechniquesechniques

Techniques from this large group repair aspecific stream problem at a defined point orstream reach. The primary goal may be tostabilize an eroding stream bank, remove a fishbarrier, daylight a storm water pipe, create in-stream fish habitat, or control channel incision(Figure 20). Stream repair techniques can beclassified by primary design objective:

· Hard bank stabilization· Soft bank stabilization· Grade control· Flow deflection· In-stream habitat enhancement· Flow diversion· Fish barrier removal

Stream repair techniques are inherently limitedby their in-stream location, which may result inthe treatment of symptoms but not theunderlying causes.

Comprehensive RestorationComprehensive RestorationComprehensive RestorationComprehensive RestorationComprehensive RestorationPPPPPracticesracticesracticesracticesractices

This technique takes a more sophisticated andcomprehensive approach toward streamrestoration. The goal is to design a morenatural geometry and habitat structure for thestream channel and banks consistent with itscurrent hydrology and sediment transportdynamics. The broad objectives for thesetechniques are to restore more natural channelmorphology and improve habitat conditions foraquatic life. This may entail natural channeldesign, dechannelization, or multipleapplications of many individual stream repairtechniques. Urban subwatersheds are anextremely challenging environment forcomprehensive stream restoration, given thedynamic changes in hydrology and sedimenttransport caused by upstream development. Astable channel form that still experiencesaltered hydrology and sediment transport maynot be hospitable to native aquatic species.

Whether the ultimate goal of comprehensivestream restoration is recovering a trout or



Once sites are adequately prepared, they canbe revegetated to improve the quality andfunctional value of the streamside zone, basedon the intended management use of the streamcorridor. Four basic strategies for revegetatingthe riparian zone are shown in Figure 22 anddescribed below.

Active ReforestationActive ReforestationActive ReforestationActive ReforestationActive Reforestation

These planting techniques are designed tomaximize the ecological benefits of a forested

flood plain by creating a mature and self-sustaining native plant community.

PPPPParks or Greenwaysarks or Greenwaysarks or Greenwaysarks or Greenwaysarks or Greenways

These plantings are applied when the streamcorridor is used for recreational activities suchas hiking, biking or nature enjoyment. Theplanting plans within these park or greenwaysettings seek to expand natural vegetativecover while still accommodating the needs ofpark users.

Upstream Retrofit: Wet Extended Detention Pond

Figure 21: Example of Comprehensive Stream Restoration ApproachThe diagram shows the combination of stream restoration techniques employed to restore Wheaton

Branch in Montgomery County, Maryland. A key element of the project was the construction of anupstream storage retrofit used to remove pollutants and control hydrology, along with riparian

reforestation and restocking of native fish species. The restoration project was built in the late 1980s, andresulted in improved fish and aquatic diversity in this formerly non-supporting stream.



Figure 22: Four Strategies to Establish Vegetation in the Riparian Area The strategy to establish riparian vegetation depends on the condition of the stream corridor, itsownership and intended management use. Strategies include active reforestation (Panel A), more

limited park/greenway plantings (Panel B), natural regeneration (Panel C) and restoration of riparianwetlands/forests (Panel D).

Natural RegenerationNatural RegenerationNatural RegenerationNatural RegenerationNatural Regeneration

This technique allows vegetation to grow backin the stream corridor by stopping mowingoperations. Although natural regeneration issimple and inexpensive, it can take a long timeto establish a mature streamside forest alongthe stream corridor. Natural regeneration mayalso result in a plant community that could bedominated by invasive or exotic plant species.

Riparian WRiparian WRiparian WRiparian WRiparian Wetland Retland Retland Retland Retland Restorationestorationestorationestorationestoration

These techniques are used to enhance orrestore degraded wetland communities found

along the flood plain. Wetlands are frequentlyassociated with stream corridors because of theclose hydrologic connection of the stream withits flood plain. In urban subwatersheds,however, the stream and its flood plain maybecome disconnected. This occurs when theelevation of the stream channel drops due tosevere channel erosion, which leaves the floodplain wetlands high and dry (Groffman et al,2003). Consequently, riparian wetlandrestoration can involve engineering techniquesto reconnect the stream with its flood plain orredirect urban storm water generated fromoutside the stream corridor to create surfacewetlands.

A. B.

C. D.



4.4 Discharge Prevention4.4 Discharge Prevention4.4 Discharge Prevention4.4 Discharge Prevention4.4 Discharge PreventionPracticesPracticesPracticesPracticesPractices

Discharge prevention practices prevent sewageand other pollutants from entering the streamfrom illicit discharges, sewage overflows, orindustrial and transport spills. Discharges canbe continuous, intermittent, or transitory, anddepending on the volume and type, can causeextreme water quality problems in a stream.Sewage discharges can directly affect publichealth (bacteria), while other discharges can betoxic to aquatic life (e.g., oil, chlorine,pesticides, and trace metals). Dischargeprevention focuses on four types of dischargesthat can occur in a subwatershed, as describedbelow.

Illicit Sewage DischargesIllicit Sewage DischargesIllicit Sewage DischargesIllicit Sewage DischargesIllicit Sewage Discharges

Sewage can get intourban streams whenseptic systems fail orsewer pipes aremistakenly or illegallyconnected to thestorm drain pipe

network. In other cases, “straight pipes”discharge sewage to the stream or ditchwithout treatment, or sewage from RVs orboats is illegally dumped into the storm drainnetwork. Research has shown that sewage isthe most common type of illicit discharge inmost communities (Brown et al., 2004). Thesedischarges can be detected by screening stormwater outfalls with dry weather flow for waterquality parameters that indicate suspectedsewage contamination. More detaileddiagnostic tests are often needed to trace theproblem up the pipe network and isolate thespecific home or business connection that isdischarging sewage or septage.

Commercial andCommercial andCommercial andCommercial andCommercial andIndustrial Il l icitIndustrial Il l icitIndustrial Il l icitIndustrial Il l icitIndustrial Il l icitDischargesDischargesDischargesDischargesDischarges

Some businesses mistakenly or illegally use thestorm drain network to dispose of liquid wastesthat can exert a severe water quality impact onstreams. Examples include shop drains that areconnected to the storm drain system; improperdisposal of used oil, paints, and solvents; anddisposal of untreated wash water or processwater into the storm drain system. A largenumber of commercial, industrial, institutional,municipal, and transport-related sites have thepotential to generate these discharges on anintermittent or transitory basis. Brown et al.(2004) provide detailed guidance on how toidentify generating sites, and describe educationand enforcement methods for eliminating illicitdischarges.

FFFFFailingailingailingailingailingSewer LinesSewer LinesSewer LinesSewer LinesSewer Lines

Sewer lines often follow the stream corridor,where they may leak, overflow or break,sending sewage directly to the stream. Thefrequency of failure depends on the age,condition and capacity of the existing sanitarysewer system. The vigilance of the local sewerauthority is also important to minimize failure.Regular inspection of sewer lines, promptresponse to overflows and leaks, and ongoingrepairs to the sewer infrastructure can sharplyreduce sewage discharge.



Industrial andIndustrial andIndustrial andIndustrial andIndustrial andTTTTTransporransporransporransporransport Spillst Spillst Spillst Spillst Spills

Tanks rupture, pipelines break, accidents causespills, and morons dump pollutants into thestorm drain system. It is only a matter of timebefore these events occur in most urbansubwatersheds, allowing potentially hazardousmaterials to move through the storm drainnetwork and reach the stream. Since spills areunpredictable, they can only be managed bymaintaining an emergency response system thatquickly reacts to spills and contains thedamage. Spill response plans are needed forstorm water hotspots, many industrial sites, andthe road system of the subwatershed.

Brown et al. (2004) provides general guidanceon the range of techniques to find, fix orprevent all four types of discharges in an urbansubwatershed. A condensed list of thedischarge prevention techniques profiled in themanual can also be found in Appendix B.

4.5 W4.5 W4.5 W4.5 W4.5 Watershed Fatershed Fatershed Fatershed Fatershed ForestrorestrorestrorestrorestryyyyyPracticesPracticesPracticesPracticesPractices

Municipalities often own or manage as muchas 10% of total subwatershed area in parks,open lands, golf courses, schools and taxdelinquent parcels. Some of these areas areprime candidates for land reclamation, whichimproves soil quality by amending it toincrease its capacity to infiltrate rainfall, andcreate better conditions for healthy plantgrowth. Manual 7 offers guidance on a rangeof land reclamation and watershed forestrytechniques; Appendix B provides a condensedsummary list.

LLLLLandandandandandReclamationReclamationReclamationReclamationReclamation

Because urban soils are extremely compacted,they often have poor vegetative cover andinfiltration capabilities. Consequently, manypervious areas in urban subwatersheds producemore storm water runoff and sediment thanundeveloped areas. Land reclamation seeks torestore soil quality on tracts of land that arevacant, abandoned or unused, or withinindividual yards. This technique includescompost and other soil amendments, tilling, andaeration. In many ways, land reclamationpractices are similar to rain gardens and otherresidential on-site retrofit practices. Landreclamation is a relatively new urbanrestoration technique, and its subwatershedbenefits can only be realized when it is widelyimplemented across a subwatershed.

UplandUplandUplandUplandUplandRRRRRevegetationevegetationevegetationevegetationevegetation

Once soil quality has been restored, trees orother forms of native cover can be planted tomeasurably increase overall forest cover withina subwatershed. The canopy interception andinfiltration created by expanded forest covercan improve stream hydrology and reduce theurban heat island effect. It should be noted thatprairie, meadows or grasslands may be theideal native vegetative cover in some regionsof the country. In any event, revegetation mustbe conducted at a widespread scale in asubwatershed to provide measurable hydrologicand water quality benefits.



Management ofManagement ofManagement ofManagement ofManagement ofNatural AreaNatural AreaNatural AreaNatural AreaNatural AreaRRRRRemnantsemnantsemnantsemnantsemnants

This practice enhances the quality of remainingforest fragments, wetlands and other naturalarea remnants in the upland areas of thesubwatershed. Like their counterparts along thestream corridor, natural area remnants arefrequently impacted by dumping, soilcompaction, erosion, invasive plants and stormwater runoff. This practice usually involves anecological assessment of the natural arearemnant to identify key stressors, followed by arestoration plan to improve its ecologicalstructure and function.

4.6 P4.6 P4.6 P4.6 P4.6 Pollution Source Controlollution Source Controlollution Source Controlollution Source Controlollution Source ControlPPPPPracticesracticesracticesracticesractices

Source control is a broad restoration practicethat seeks to prevent pollution from residentialneighborhoods or storm water hotspots. Whichsource control practices are applied depends onthe pollutants of concern and the majorpollutant source areas identified in thewatershed. Source control practices focuseducational, enforcement, and technicalresources on changing the resident behaviors orbusiness operations that are causing thepollution. Manual 8 provides extensiveinformation on 21 stewardship practices thatcan be applied in residential neighborhoods,along with 15 pollution prevention techniquesused to control storm water hotspots. A list ofsource control practices profiled in the manualcan be found in Appendix B.

ResidentialResidentialResidentialResidentialResidentialStewardshipStewardshipStewardshipStewardshipStewardship

Subwatershed residents engage in manybehaviors that can influence stream quality.You may want to focus on changing negativebehaviors such as over-fertilizing, oil dumping,littering, or excessive car washing andpesticide use. Alternatively, your focus may beon encouraging positive behaviors such as treeplanting, properly disposing of householdhazardous wastes, and picking up after pets. Ineither case, residential stewardship involvesdesigning a targeted education campaign thatdelivers a specific message and changesresident behavior (Swann, 2000). Often, theeducational campaign is supported byincentives and the provision of convenientmunicipal services such as free compost forsoil amendments, free lawn soil testing, adviceon nontoxic ways to deal with pests, or oilrecycling directories.

To devise an effective neighborhoodstewardship program, it is important tounderstand the range of homeowner behaviorsthat contribute to storm water pollution. Sinceeach neighborhood has its own distinctivecharacter, it is helpful to assess homeownerbehaviors and pollution sources at theneighborhood scale (Figure 23). TheNeighborhood Source Assessment (NSA)component of the USSR survey, described inManual 11, systematically examines fivecommon pollution source areas in everyneighborhood:

Overall Neighborhood Character: What is theaverage age, lot size and construction activitywithin the neighborhood? Are there septicsystems that could become a pollution source?Is there an active homeowner or civicassociation to help with outreach?

Lawn and Yard Practices: What proportion oflawns in the neighborhood is intensivelymanaged from the standpoint of fertilization,



Figure 23: Pollution Source Control Opportunities in Residential NeighborhoodsNearly two dozen pollution source control opportunities can exist within a residential neighborhood.

They can be systematically evaluated by looking at lawns and yard practices, rooftop connections, thecondition of sidewalks, driveways and curbs, and the management of any common areas.

pesticide use, and irrigation? What opportunitiesexist in the yards to expand natural landscaping,tree canopy, and backyard composting?

Rooftops: Are the rooftops directly connectedto the storm drain system, and, if so, what is thepotential to disconnect, capture or treat rooftoprunoff?

Sidewalks, Driveways and Curbs: Arepollutants, pet waste, or organic matteraccumulating on these surfaces? What can beinferred about driveway cleaning, carmaintenance and other housekeeping practicesin these areas?

Stewardship of Common Areas: Is communityopen space present in the neighborhood in theform of storm water ponds, buffers, floodplains, forest conservation areas, or

streetscapes? If so, what are the prevailingvegetative management, maintenance andhousekeeping practices in these commonareas?

Most subwatersheds contain multipleneighborhoods that can differ sharply in boththe potential severity of their pollution sourcesand opportunities for neighborhood restoration.

Hotspot Source ControlHotspot Source ControlHotspot Source ControlHotspot Source ControlHotspot Source Control

This restoration practice involves applyingpollution prevention practices at commercial,industrial, institutional, municipal, andtransport-related sites that are suspected orconfirmed storm water hotspots. Pollutionprevention practices may be legally requiredunder local or state storm water permits atmany of these hotspots. While dozens of

Yards and

L

Rooftops

Sidewalks, Driveways, and Curbs

Common Areas

Lawns

and Curbs



Turf Practice

Waste Storage

Downspouts

Loading Dock

Vehicle Fueling

Parking Lots

Figure 24: Investigating Potential Storm Water HotspotsStorm water hotspots are sites that produce higher levels of storm water pollution and/or a greater

risks of spills, leaks and discharges, and are created by vehicles, outdoor storage, wastemanagement, plant maintenance, grounds care and other site operations and practices.

pollution prevention techniques are available,managers must identify the unique combinationof techniques that will address the actualpollution problems encountered at each site.Thus, the first step in hotspot source controlinvolves a thorough investigation of stormwater problems, spill risks, and pollutionsources at the site. A Hotspot Site Investigation(HSI) evaluates current operations with respectto six potential pollution sources (Figure 24):

Vehicular Sources: Are vehicles washed,fueled, repaired, or stored at the site that couldserve as a potential source of pollution?

Material Handling: Are pollutants being storedor loaded outside where they may be exposedto rainfall?

Waste Management: Can any wastes producedat the site get into the storm drain system?(e.g., trash dumpsters, used oil, productdisposal).

Physical Plant Practices: Do any of themaintenance practices for the building andparking lots have the potential to pollute stormwater?

Turf and Landscaping: Are the fertilizers orpesticides used to maintain the grounds apotential pollution source?

Miscellaneous Sources: Are there uniqueoperations at the site that can producepollution? (e.g., marinas, swimming pools, andgolf courses)

A unique combination of pollution preventionpractices is prescribed for each storm waterhotspot based on the HSI. This prescriptionmay involve structural and nonstructuraltechniques, along with the employee trainingneeded to make them happen. Guidance onconducting an HSI can be found in Manual 11.



4.7 Municipal Practices and4.7 Municipal Practices and4.7 Municipal Practices and4.7 Municipal Practices and4.7 Municipal Practices andProgramsProgramsProgramsProgramsPrograms

Municipalities can play at least six pivotalroles in subwatershed restoration. First,communities maintain much of the physicalinfrastructure in a subwatershed, includingroads, sewers, and storm drain systems. Inmany cases, communities can reduce orprevent pollutants from entering thesubwatershed by changing their infrastructuremaintenance policies. Second, maintenancepractices set the rules governing howdevelopment and redevelopment proceed.When crafted properly, these rules can activelypromote better development practices thatsupport long-term subwatershed restorationgoals.

Third, municipalities are usually a significantlandowner in most subwatersheds, and canpractice better stewardship on the lands theyown or control. Fourth, municipalities operatecertain facilities that are well-known stormwater hotspots. Common examples includesolid waste facilities, public works yards, fleetstorage lots and maintenance depots. Many ofthese operations are required to implementsource control or pollution prevention practices.Fifth, municipalities can act as the directservice provider to help residents andbusinesses practice better stewardship.Examples include local programs toconveniently dispose of yard wastes, used oilor household hazardous wastes.

Lastly, municipalities can play a strong role inboth education and enforcement to promotebetter stewardship by residents and businesses.More guidance on municipal practices andprograms that can support subwatershedrestoration can be found in Manual 9; acondensed list is presented in Appendix B.

Street andStreet andStreet andStreet andStreet andStorm DrainStorm DrainStorm DrainStorm DrainStorm DrainPPPPPracticesracticesracticesracticesractices

Municipalities own and maintain much of theroad and storm drain infrastructure in asubwatershed. Routine maintenance practicessuch as road and bridge repairs, snow removaland road salting can cause storm waterpollution unless employees are properly trainedon best practices. On the other hand, municipalmaintenance practices such as street sweeping,catch basin cleanouts, and streetscaping canhelp remove pollutants from subwatersheds.The degree of pollutant reduction depends onhow frequently and systematically eachpractice is implemented across a subwatershed.

Best PBest PBest PBest PBest Practices forractices forractices forractices forractices forDevelopment orDevelopment orDevelopment orDevelopment orDevelopment orRedevelopmentRedevelopmentRedevelopmentRedevelopmentRedevelopment

Urban subwatersheds undergo a continualprocess of development and redevelopment.Indeed, it has been estimated that an urbansubwatershed will completely redevelop over a50 year timeline (GVSDD, 2002), presenting anexcellent long-term opportunity to retrofit betterstorm water practices during the redevelopmentprocess. By crafting better criteria fordevelopment and redevelopment, communitiescan actively promote “smart site practices” thatsupport long-term subwatershed restorationgoals. Smart site practices are innovativetechniques to create green space and creativelytreat storm water at redevelopment and infillsites (Kwon, 2001). They can be applied toboth private and public sector redevelopmentprojects in highly urban subwatersheds.



Stewardship ofStewardship ofStewardship ofStewardship ofStewardship ofPPPPPublic Lublic Lublic Lublic Lublic Landandandandand

It is not uncommon for a municipality to own orcontrol as much as 10% of all the land within asubwatershed, when all of the parks, schools,golf courses, rights of way, easements, openspace, municipal buildings and tax delinquentparcels are combined. Even more land may beowned or controlled by local utilities or stateand federal agencies. While this land reserve isquite large, it is widely dispersed and managedby many entities for many different purposes.This restoration practice seeks to educatemunicipal landowners about subwatershedrestoration goals and enlist them as partners inthe restoration effort. The partners whomanage the lands held in public trust canimprove their land stewardship and providedemonstration sites for both stream corridorand subwatershed restoration practices. Anexample of public lands stewardship is thereforestation of the grounds of a local middleschool.

MunicipalMunicipalMunicipalMunicipalMunicipalStewardshipStewardshipStewardshipStewardshipStewardshipPPPPProgramsrogramsrogramsrogramsrograms

Municipalities provide many direct services thatcan improve stewardship by residents andbusinesses alike. Some of these programs maybe required under their NPDES storm waterpermit or by state regulation, while others arelocal initiatives to increase local watershedawareness. Examples of municipal stewardshipinclude programs organized to do thefollowing:

· Enforce illegal dumping· Stencil storm drains· Adopt a stream· Collect household hazardous wastes· Collect used oil for recycling

· Provide lawn care advice· Provide soil testing or compost· Disconnect residential rooftops· Inspect septic systems· Citizen hotlines

These programs are intended to make each actof personal stewardship as easy and convenientas possible to achieve the greatest pollutantreduction for the subwatershed. Stewardshipprograms require a carefully targeted educationcampaign to increase participation, as well asan efficient and timely delivery service.

WWWWWatershed Education andatershed Education andatershed Education andatershed Education andatershed Education andEnforcementEnforcementEnforcementEnforcementEnforcement

Municipalities can wield both carrots andsticks to promote pollution preventionpractices and respond to severe water qualityproblems. Municipal education efforts caninclude basic outreach, subsidies, discounts,and recognition programs. Enforcementmethods can include inspections, newregulations, certification, and civil enforcementproceedings. The full range of carrots andsticks available to a municipality is describedin Manual 8.

4.8 Choosing the Right4.8 Choosing the Right4.8 Choosing the Right4.8 Choosing the Right4.8 Choosing the RightCombination of RCombination of RCombination of RCombination of RCombination of RestorationestorationestorationestorationestorationPPPPPractices for a Subwatershedractices for a Subwatershedractices for a Subwatershedractices for a Subwatershedractices for a Subwatershed

The range of practices that can potentiallyrestore urban subwatersheds is impressive, butalso daunting. From a planning standpoint,subwatershed restoration potential is basicallygoverned by the size of the remaining streamcorridor, and the amount of subwatershed areathat can be effectively treated. Since bothfactors are closely related to impervious cover,a general sense of restoration potential can beinferred from the subwatershed ICMclassification.

The basic relationship is presented in Figure25, which shows how subwatershed ICinfluences the feasibility of implementingrestoration practices. The chart indicates thedegree to which a given restoration techniquecan be implemented across each ICM



Figure 25: General Feasibility of Retrofit Practices at DifferentLevels of Subwatershed IC

This chart provides general guidance on the subwatershed conditions where the restorationtechniques can be most widely applied. Actual restoration potential should always be

assessed in the field, but the ability to widely implement some restoration techniques is oftenlimited in the most intensely developed subwatersheds, due to lack of available land in the

stream corridor or upland areas.

Subwatershed Impervious Cover Restoration Practice 10 to 25% 25 to 40% 40 to 60% 60 to 100%

Storm Water Retrofit Practices Storage Retrofit On-site Non-Residential Retrofits On-site Residential Retrofits

Stream Repair Practices Stream Clean-ups Stream Repairs Comprehensive Restoration

Riparian Management Practices Site Preparation Active Reforestation Park/Greenway Plantings Natural Regeneration Riparian Wetland Restoration

Discharge Prevention Practices Illicit Sewage Connections Other Illicit Connections Failing Sewage Lines Industrial and Transport Spills

Watershed Forestry Practices Land Reclamation Upland Revegetation Natural Area Remnant

Pollution Source Control Practices Residential Source Controls Hotspot Source Controls

Municipal Practices and Programs Street and Storm Drain Cleaning Best Practices for Redevelopment Stewardship of Public Land Municipal Stewardship Programs Education and Enforcement KEY

Technique is normally feasible and can be widely applied across subwatershed Technique is often feasible, depending on subwatershed characteristics Individual sites can be found, but widespread implementation across subwatershed is limited Technique is generally not feasible in the subwatershed



subwatershed category. Note that the non-supporting subwatershed category has beendivided into a lower range (25 to 40% IC) andan upper range (40 to 60% IC). As can beseen, restoration practices become less feasibleas subwatershed IC increases. This isparticularly true for stream corridor restorationpractices such as storm water retrofits, streamrestoration and riparian reforestation.

All seven restoration practices are potentiallyfeasible within impacted subwatersheds, andmany of these practices continue to be feasiblein the lower range of the non-supportingcategory. Obviously, their actual feasibilitycannot be determined until systematic desktopand field surveys are conducted in asubwatershed.

By contrast, stream corridor restorationpractices are seldom feasible in the upper rangeof non-supporting subwatersheds (40 to 60%IC) and are rarely feasible in urban drainagesubwatersheds. These subwatersheds may besuitable for upland practices that reduce orprevent pollution, such as dischargeprevention, municipal practices, and pollutionsource controls.

The feasibility of restoration practices stronglyinfluences the ability to meet various waterquality, biological and social goals in each classof subwatershed. Figure 26 illustrates thegeneral ability to meet various goals at differentlevels of subwatershed imperviousness. Thechart is based on past experience assessingrestoration potential in many subwatershedsacross the country, and is only intended as ageneral planning guide, as exceptions can andwill occur. Still, the chart is a useful frameworkfor analyzing how impervious cover influencesthe ability to meet subwatershed goals.

Restoration Goals for ImpactedRestoration Goals for ImpactedRestoration Goals for ImpactedRestoration Goals for ImpactedRestoration Goals for ImpactedSubwatershedsSubwatershedsSubwatershedsSubwatershedsSubwatersheds

Impacted subwatersheds usually have thegreatest restoration potential, since theyexperience only moderate stream degradation,have an intact stream corridor, and normallyhave enough land available in thesubwatershed to install restoration practices.Consequently, many restoration goals can beachieved in impacted subwatersheds, assumingthat enough feasible retrofit sites can be foundto assure widespread treatment. If this can bedone, it may be possible to set goals to actuallyimprove physical, biological and water qualityindicators for impacted subwatersheds,particularly at the low end of its IC range.Thus, it may be possible to systematicallyrestore habitat throughout the stream network,reduce pollutant loads to rural backgroundlevels, meet water contact recreation standardsduring dry weather periods, partially recoveraquatic diversity, and possibly even restore afishery. Similarly, it is reasonable to expectthat many community goals, such as streamcorridor enhancement, can still be achieved inimpacted subwatersheds.

RRRRRestoration Goals forestoration Goals forestoration Goals forestoration Goals forestoration Goals forNon-supporNon-supporNon-supporNon-supporNon-supporting Subwatershedsting Subwatershedsting Subwatershedsting Subwatershedsting Subwatersheds

Fewer restoration goals can be achieved innon-supporting subwatersheds, although somesubwatersheds at the lower end of the IC range(25 to 40% IC) may show promise for partialrestoration if they can be extensively treatedwith retrofits and pollution source controls. Theprimary restoration goal in many non-supportingsubwatersheds is to reduce pollutant loads bycomprehensively applying storage and on-siteretrofits, discharge prevention, source controland municipal practices. Full restoration ofaquatic diversity can be an elusive goal,although it may be possible to find someindividual stream reaches that can be repaired.In addition, it may still be possible to meetcommunity goals for the stream corridor, suchas recreation, flood control, and aesthetics.



Percent Subwatershed Impervious Cover Subwatershed Restoration Goals

10 to 25 25 to 40 40 to 60 60 to 100

Water Quality Reduce pollutants of concern Prevent illegal discharges/spills Meet water quality standards Reduce sediment contamination Allow water contact recreation Protect drinking water supply Biological Restore aquatic diversity Restore wetlands/natural areas Expand forest cover Restore/reintroduce species Improve fish passages Enhance wildlife habitat Remove invasive species Keep shellfish beds open Enhance riparian areas Physical/Hydrological Increase groundwater recharge Reduce channel erosion Reclaim stream network Reduce flood damage Reconnect with floodplain Restore physical habitat Protect municipal infrastructure Community Eliminate trash/debris Create greenways/waterfront access/open space

Revitalize neighborhoods Improve aesthetics/beautification Increase citizen awareness Improve recreation Increase angling opportunities

Goal can often be achieved in many subwatersheds Goal can be achieved in some subwatersheds depending on degree of treatment Goal can possibly be achieved in unusual circumstances Goal generally not achievable

Figure 26: General Ability to Meet Subwatershed Goals at Different Levels of Subwatershed IC

This planning chart indicates how subwatershed impervious cover influences the degree of potential treatment, and ultimately the ability to meet specific subwatershed goals. Actual treatment potential for any subwatershed should always be determined through desktop analyses and field assessments. The chart

simply indicates that the some restoration goals or objectives cannot always be attained in the most intensely developed subwatersheds, due to inadequate levels of treatment.



Restoration Goals for UrbanRestoration Goals for UrbanRestoration Goals for UrbanRestoration Goals for UrbanRestoration Goals for UrbanDrainage SubwatershedsDrainage SubwatershedsDrainage SubwatershedsDrainage SubwatershedsDrainage Subwatersheds

Given the intensity of development in urbandrainage subwatersheds, it is hard to findenough feasible retrofit sites to meet mostbiological goals. Thus, the prospects forrestoring aquatic diversity or stream habitat inurban drainage subwatersheds are extremelylimited, although some individual reaches mayshow modest restoration potential. Someopportunities may exist to mitigate floodingproblems, restore natural area remnants or

create greenways to link remaining fragmentsof intact stream corridor. It is also possible toachieve incremental reductions in downstreampollutant export in urban drainagesubwatersheds, although it may not be realisticto expect major water quality improvementswithin the “streams” themselves.

The next two chapters describe the methodsused to discover the actual restoration potentialfor all three types of subwatersheds.


Chapter 5: Envisioning Restoration

Chapter 5: Envisioning RChapter 5: Envisioning RChapter 5: Envisioning RChapter 5: Envisioning RChapter 5: Envisioning Restorationestorationestorationestorationestoration

The most important skill in urban watershedrestoration is an ability to envision restorationopportunities within the stream corridor andupland areas. It takes a practiced eye to findthese possibilities in a landscape dominated bythe built environment. Still, many goodrestoration opportunities can be discovered.This brief chapter describes how and where tofind restoration opportunities in yoursubwatershed.

Subwatersheds are a complex mosaic of bothimpervious and pervious cover. The bestrestoration opportunities are usually found inthe remaining pervious areas. As much as threeto 5% of subwatershed area may be needed tolocate enough restoration practices to repair orimprove stream conditions. Further, this landmust be located in the right place and becontrolled by willing landowners. Lastly,restoration sites are distributed across dozensand sometimes hundreds of small parcelswithin a subwatershed. While a quick glance ata city map might make this land requirementseem unattainable in most impacted and non-supporting subwatersheds, many excellentrestoration opportunities can be discoveredwith a practiced eye, some imagination, and alot of detailed map work.

The process of discovering these opportunitiesis called “envisioning restoration,” and consistsof two basic techniques: intensively analyzingmaps and aerial photographs, and conducting arapid reconnaissance of actual conditions in thesubwatershed. Both techniques are as much askill as a science, and certainly no computermodel can do the same jobs. Detailed methodsfor systematically envisioning restoration areoutlined in Manuals 2, 10, and 11. Table 7summarizes the 11 places to envisionrestoration in any subwatershed, and theremainder of the chapter reviews key featuresto look for in the stream corridor and itssubwatershed.

5.1 The R5.1 The R5.1 The R5.1 The R5.1 The Remnant Streamemnant Streamemnant Streamemnant Streamemnant StreamCorridorCorridorCorridorCorridorCorridor

The first place to explore is the remainingstream corridor (Figure 27). Normally, thestream corridor comprises about three to 5% ofthe total area of an undeveloped subwatershed,but it can be much smaller in highly urbansubwatersheds due to encroachment. Indeed,the stream corridor can be eliminated in someultra-urban subwatersheds. Still, the streamcorridor is the first place to envisionrestoration.

Regrettably, the urban stream network is poorlyportrayed on most maps, and many first andsecond order streams are not shown. Streaminterruptions, crossings and channel alterationsare not depicted, and the width and conditionof the stream corridor are seldom delineatedwith any accuracy (indeed, it is usually shownon maps as undefined white space betweenbuildings, streets and parking lots). Aerialphotographs that show current vegetativecondition are the best tool for defining theapproximate boundaries of the stream corridor.

1. Remnant Stream Corridor2. Existing Storm Water Infrastructure3. Open Municipal Land4. Natural Area Remnants5. Road Crossings and Rights-of-way6. Large Parking Lots7. Storm Water Hotspots8. Residential Neighborhoods9. Large Parcels of Institutional Land10. Sewer Network11. Streets and Storm Drains

Table 7: Eleven Places to EnvisionRestoration in a Subwatershed



While maps and photos are a starting point, thestream corridor can only be truly seen bywalking the entire stream network. The UnifiedStream Assessment (USA), described inManual 10, has been developed as a tool tosystematically evaluate the remaining streamarea. The stream corridor is an important placeto envision restoration because it is thetransition zone between the upland storm drainnetwork and the urban stream. Within thisnarrow zone, there is often enough availableland to install restoration practices to repair orimprove stream conditions. These includestorage retrofits, riparian management anddischarge prevention practices

5.2 Existing Storm W5.2 Existing Storm W5.2 Existing Storm W5.2 Existing Storm W5.2 Existing Storm WaterateraterateraterInfrastructureInfrastructureInfrastructureInfrastructureInfrastructure

The next place to envision restoration in asubwatershed is the existing storm waterinfrastructure (Figure 28). Each subwatershedhas a vast network of catch basins, stormdrains, outfall pipes, detention ponds, floodways and storm water practices that conveystorm water. The existing storm water systemis attractive for restoration for two reasons.First, as much as 3% of total subwatershed areamay be devoted to the storm water system(although often at the expense of the existingstream corridor). Second, since land is already

devoted to storm water management, it is mucheasier to get approval from owners to retrofit it.

The restoration potential of a storm waterinfrastructure depends largely on its age. Stormwater systems constructed prior to 1970 aremostly underground, with limited surface landdevoted to flood control projects. Systemsfrom 1970 to 1990 were often built with stormwater detention ponds designed to control peakflood discharges. Detention ponds, which areoften quite large, greatly add to the surfaceland available for potential restoration, and arealways a favorite target for storage retrofits.Systems designed over the last decade reflectthe growing trend toward the treatment ofstorm water quality, and may contain dozens ofstorm water treatment practices of all differentsizes and types. The surface land area devotedto storm water practices can consume as muchas three to 5% of subwatershed area,depending on local storm water criteria. Thesenewer practices are a particularly attractiveretrofitting target.

A good map of the urban storm water pipesystem is extremely helpful, if available.Several locations on these maps deserve closescrutiny: outfalls where storm water pipesdischarge, open land adjacent to these outfalls,and any surface land devoted to storm waterdetention and/or treatment. These locations are

A B

Figure 27: Envisioning Restoration in the Remnant Stream CorridorDespite having 20% IC, this subwatershed has a relatively intact stream corridor (Panel A), where

many potential sites where storm water retrofits, stream restoration and riparian reforestationprojects can be investigated (Panel B).



A B

Figure 28: Envisioning Restoration Within Existing Storm Water InfrastructureOlder storm water detention ponds are a favorite target for conversion to storage retrofits

practices (Panel A). Another good location to investigate potential storage retrofits is the pointwhere storm water pipes outfall in the stream corridor (Panel B).

prime candidates for storage retrofits andstream daylighting practices. Storm wateroutfalls are also the starting point to look forillicit discharges that may be flowing throughthe storm drain system.

In reality, the storm water pipe network ispoorly mapped in most communities, and oftenreflects a confusing blend of pipes andstructures built in many different eras. So onceagain, field reconnaissance is necessary to seehow it actually works. In practice, the manyroutes that storm water travels to get to thestream corridor must be traced by working upfrom each storm drain outfall.

5.3 Open Municipal L5.3 Open Municipal L5.3 Open Municipal L5.3 Open Municipal L5.3 Open Municipal Landandandandand

The next place to envision restoration is inlarge parcels of open municipal land, such asparks, public golf courses, schools, rights-of-way or protected open space (Figure 29).Municipal lands are attractive areas forrestoration because of their large size andownership. While municipal lands are managedfor different purposes, portions of each parcelmay be good candidates to creatively locate allseven restoration practices. In addition, openlands are easy to distinguish on either aerialphotographs or tax maps, and are easy toconfirm in the field.

5.4 Natural Area R5.4 Natural Area R5.4 Natural Area R5.4 Natural Area R5.4 Natural Area Remnantsemnantsemnantsemnantsemnants

The next place to envision restoration is in thelarger natural area remnants in thesubwatershed (Figure 30). Forest and wetlandfragments are frequently located near thestream corridor, and the larger contiguousparcels are hard to miss when looking at anaerial photograph or resource inventory map.Larger remnants and their adjacent marginsalways deserve close scrutiny in the field. Atwo-acre size threshold is often used to selectparcels for field analysis. Natural arearemnants are not a preferred location forintrusive restoration practices (such as a largestorage retrofit), but may be good targets forforest or wetland restoration. In addition, thepossibility of expanding natural areas orlinking them to the stream corridor or otherremnants should always be considered.

5.5 R5.5 R5.5 R5.5 R5.5 Road Crossings andoad Crossings andoad Crossings andoad Crossings andoad Crossings andHighway Rights-Highway Rights-Highway Rights-Highway Rights-Highway Rights-of-of-of-of-of-WWWWWayayayayay

Road crossings and rights-of-way are alwaysworth exploring for restoration opportunities(Figure 31). Stream crossings are quite easy tospot on aerial photos or regular maps. Twospecific areas of the map should be located: thepoints where roads cross the stream corridor,and large rights-of-way, such as cloverleafinterchanges and highway access ramps.



Each road crossing presents both a problemand an opportunity. Bridges and culverts thatcross the corridor are always suspected barriersto fish migration, but they may alsounintentionally act as a useful grade control ina rapidly incising stream. Also, road designerslike to maintain grade when crossing streams,so they often build earthen embankmentsacross the flood plain to approach the bridgeand culvert. In very small streams, thesecrossings can be modified to providetemporary storage and treatment of storm waterupstream of the crossing. Lastly, road crossingsoften provide the best access to the streamcorridor for stream assessments, cleanups andconstruction equipment.

Larger highways often have fairly large parcelsof unused land near interchanges in the form ofcloverleafs and approach ramps. These parcelscan be an ideal location both for storageretrofits and reforestation, because they receivepolluted runoff from the highway and generallyserve no other purpose.

Figure 29: Envisioning Restoration on Open Municipal LandsPortions of open municipal land are often good candidates for locatingrestoration practices, particularly along the property margins. Parks,

schools and ballfields (shown in photo) are always worth evaluating in anysubwatershed.

5.6 L5.6 L5.6 L5.6 L5.6 Large Parge Parge Parge Parge Parking Larking Larking Larking Larking Lotsotsotsotsots

Large parking lots really stand out in an aerialphotograph or land use map (Figure 32) andare of great interest for several reasons. First,they produce more storm water runoff andpollution on a unit area basis than any otherland use in a subwatershed. As such, they areobvious targets for on-site or storage retrofits.Second, large parking lots generally signal thepresence of large clusters of commercial,industrial or institutional lands often associatedwith storm water hotspots. While these areascan be easily identified from a desktop, it isusually necessary to visit each one todetermine its actual potential for retrofitting orsource control. In particular, it is important toassess how storm water is currently handled inthe parking lot, and look for unused landadjacent to the lot that may be suitable for aretrofit.



Figure 30: Envisioning Restoration in Natural Area RemnantsMany natural areas still remain even in highly urban subwatersheds (Panel A), although these

fragments are often highly stressed, and may require active restoration or intensive managementto improve their subwatershed value (Panel B).

Figure 31: Envisioning Restoration at Road Crossings and Rights-of-WayRoad crossings are always of particular interest in a subwatershed. This photo shows the 28

roads crossing in this small subwatershed. Each crossing can be a potential fish barrier,storage retrofit site, stream grade control, or access point to the stream corridor.



5.7 Storm W5.7 Storm W5.7 Storm W5.7 Storm W5.7 Storm Water Hotspotsater Hotspotsater Hotspotsater Hotspotsater Hotspots

The next place to envision restoration is in themany storm water hotspots in a subwatershed.Storm water hotspots are the commercial,industrial, institutional, municipal, andtransport-related land uses that tend to producehigher levels of storm water pollution, orpresent a higher risk for spills, leaks and illicitdischarges (Figure 33). The number, type anddistribution of storm water hotspots varyenormously between subwatersheds. Hotspotsare exceedingly hard to find, and many arequite small and out of the way. Maps and aerialphotos are of little value in finding them;instead, they can be found by searchingdatabases that contain standard business codesor permits, or by driving the entiresubwatershed looking for them, or both. TheUSSR, described in Manual 11, was designedto find these elusive hotspots and targetappropriate pollution prevention practices.

5.8 R5.8 R5.8 R5.8 R5.8 Residential Neighborhoodsesidential Neighborhoodsesidential Neighborhoodsesidential Neighborhoodsesidential Neighborhoods

Residential neighborhoods are the next place toenvision restoration. They are easy to see on amap, but must be visited to be truly understood(Figure 34). Each residential neighborhood hasa distinctive character in terms of age, lot size,tree cover, lawn size, and general upkeep. Inaddition, neighborhoods tend to be rather

A B

Figure 32: Envisioning Restoration in Large Parking LotsLarge parking lots produce the highest unit area storm water runoff and pollutant loadings ofany subwatershed land use, and stand out in most aerial photographs (Panel A). Each large

parcel should always be investigated to see if storage or on-site retrofit practices can mitigatetheir impact on the stream (Panel B).

homogenous when it comes to residentbehavior, awareness and participation inrestoration efforts. Each unique neighborhoodcharacteristic directly affects the ability towidely implement residential restorationpractices, such as on-site retrofits andresidential stewardship practices. In general, itis not easy to discern neighborhoodcharacteristics from a map or even an aerialphotograph. Instead, the Neighborhood SourceAssessment (NSA) component of the USSRcan be used to collect quantitative data onneighborhood characteristics to determine theirrestoration potential.

5.9 L5.9 L5.9 L5.9 L5.9 Large Institutional Large Institutional Large Institutional Large Institutional Large Institutional LandandandandandOwnersOwnersOwnersOwnersOwners

Large institutional land owners have the lastremaining land worth prospecting forrestoration potential in a subwatershed (Figure35). Examples include hospitals, colleges,corporate parks, private golf courses,cemeteries and private schools. Inspection ofaerial photos may reveal that institutions haveunderutilized areas on their grounds withrestoration potential. These sites can beproblematic, since it may be hard to expendlocal funds to improve private lands. Also,some landowners may be reluctant to bear thecost and maintenance burden associated withrestoration projects. However, other



Figure 33: EnvisioningRestoration for Storm

Water HotspotsStorm water hotspots arevery hard to find, given

their small size and unevendistribution in most urban

subwatersheds. Fieldinvestigations are almostalways needed to confirm

locations of severehotspots, although analysis

of business or permitdatabases can be used to

narrow the search.

Figure 34: Envisioning Restoration in Residential NeighborhoodsEach residential neighborhood has its own distinctive character, based on its age, lot size, vegetativecover and housekeeping. These characteristics greatly influence opportunities for residential sourcecontrol, which is evident when a large lot suburban neighborhood (Panel A) is compared to small lot

urban neighborhood (Panel B).

A B

Figure 35: EnvisioningRestoration on Large

Parcels of Institutional LandInstitutions such as this collegecampus, may have unused land

on their property that may besuitable for locating

subwatershed restorationpractices.



Figure 36: Envisioning Restoration in the Sewer SystemWhile the sewer system is mostly underground (Panel A), manholes (Panel B) and sewercrossings near the stream corridor (Panel C) should always be investigated to check for

potential sewage leaks and discharges.

A C B

institutional landowners are actively involvedin the community and may be willing to partnerin restoration efforts.

5.10 The Sewer System5.10 The Sewer System5.10 The Sewer System5.10 The Sewer System5.10 The Sewer System

The sewer system is always an important placeto envision restoration potential, although it isintrinsically difficult to see since most of it islocated underground (Figure 36). Mostcommunities have good maps of their sewerpipe networks, although older portions may bemuch less reliable. The key factor to determineis whether the sewer system is a source ofsewage discharges to the stream corridor that itoften parallels. The severity of sewagedischarge depends on the age, condition, andcapacity of the sewer network. In addition,urban watersheds are not always fully sewered;some are partly served by existing or relictseptic systems, which can be a source ofpollution.

5.11 Streets and Storm5.11 Streets and Storm5.11 Streets and Storm5.11 Streets and Storm5.11 Streets and StormDrain InletsDrain InletsDrain InletsDrain InletsDrain Inlets

The last area to envision restoration potentialincludes the street surfaces and storm draininlets of a subwatershed (Figure 37). Pollutantstend to accumulate on street surfaces andcurbs, and may be temporarily trapped withinstorm drain catch basins and sumps. Thesestorage areas often represent the last chance to

remove pollutants and trash before they washinto the stream. Municipal maintenancepractices, such as street sweeping, catch basinclean-outs and storm drain stenciling, canpotentially remove some fraction of thesepollutants, under the right conditions. Thesemunicipal practices are particularly well-suitedfor highly urban subwatersheds that have manystreets, but few other feasible restorationoptions.

While good street maps are almost alwaysavailable, accurate maps of storm drain inletlocations can be much harder to find. TheStreets and Storm Drains (SSD) component ofthe USSR helps to qualitatively assess thedegree of actual pollutant accumulation withinstreets, curbs and catch basins in thesubwatershed. The SSD also looks atfeasibility factors, such as parking, traffic,access and pavement condition, that willdetermine if street sweeping or catch basinclean-outs will be effective or practical in aparticular subwatershed.

5.12 Summar5.12 Summar5.12 Summar5.12 Summar5.12 Summaryyyyy

This chapter described how and where tosearch for restoration potential in urbansubwatersheds. Each subwatershed has adifferent combination of opportunities and thusdifferent restoration potential. The next chapterdescribes a framework for translating thesepossibilities into a realistic subwatershed plan.



A B

Figure 37: Envisioning Restoration on Streets and Storm Drain InletsPollutants and trash can accumulate on street surfaces and curbs (Panel A) or within

storm drain catch basins and sumps (Panel B). Street sweeping and catch basincleanouts may be the last chance to remove these pollutants in highly urban

subwatersheds with few other restoration options.




Chapter 6: A Framework for Small Watershed Restoration

Chapter 6: A FChapter 6: A FChapter 6: A FChapter 6: A FChapter 6: A Framework for Smallramework for Smallramework for Smallramework for Smallramework for SmallWWWWWatershed Ratershed Ratershed Ratershed Ratershed Restorationestorationestorationestorationestoration

Figure 38: Overview of the Eight-Step Framework to Restore Urban Watersheds

This chapter outlines a framework to guide youthrough actions needed to develop, adopt,implement and track a small watershedrestoration plan. Developed over the lastdecade, this general framework applies tourban subwatersheds, but can also be applied atthe watershed level. The framework isparticularly useful for organizing the manydifferent tasks needed to produce effectivewatershed restoration plans, regardless ofwhether the plan is prepared by a municipality,watershed group, private consultant, or acombination of all three.

The eight steps of the framework are shown inFigure 38. As many as four different methodsare needed to complete each step, including adesktop analysis, field assessment, stakeholderinvolvement and restoration managementmethods (Figure 39).

Desktop analysis methods help organize, mapand interpret subwatershed information to makebetter restoration decisions. Rapid fieldassessment methods occur in both the stream

corridor and subwatershed, and are used toidentify restoration opportunities, design andrank individual restoration projects, andmeasure improvements in stream health.Stakeholder involvement methods are used toidentify and recruit stakeholders and structuretheir involvement in the restoration planningprocess. Lastly, restoration managementmethods document key decisions made duringeach step of restoration plan development.

This chapter provides a condensed overview ofthe planning framework; Manual 2 providesmuch greater detail on the specific methodsused in each step. You should regard theframework as a starting point to structure yourefforts, and adapt it to fit your unique goals,budget constraints and partners. For example, ifyou have already decided whichsubwatershed(s) to restore, you should skipsteps 1 and 2. Also, while our approach outlinesthe simplest, fastest and least expensive way toperform each task, you may choose moresophisticated methods in order to justify thecommunity investment in watershed restoration.

1. Choose initial watershed goals

2. Screen mostrestorable watersheds

3. Evaluatesubwatershedrestorationpotential

4. Investigate individualrestoration projects

5. Assemble projects into watershed plan

6. Assess whether planmeets watershed goals

7. Implementsubwatershed plan

8. Monitor, revise, go tonext subwatershed



Figure 39: Detailed Steps and Tasks Involved in theRestoration Planning Process

Each step in the planning process usually has its own associated desktop analysis, fieldassessment, stakeholder involvement, or management product.



Step 1: Develop WStep 1: Develop WStep 1: Develop WStep 1: Develop WStep 1: Develop WatershedatershedatershedatershedatershedRestoration GoalsRestoration GoalsRestoration GoalsRestoration GoalsRestoration Goals

It is surprising how many watershed restorationefforts have started with neither clearagreement on the specific goals and objectivesthey are expected to accomplish, nor athorough understanding of available planningresources. Therefore, this issue should beaddressed as early as possible to set clearexpectations for watershed restoration.

Needs and Capabilities Assessment (NCA)This desktop analysis helps evaluate the factorsdriving local restoration and find availableresources to make it happen. A needs andcapabilities assessment (NCA) examines twoareas. The first part comprehensively analyzesfederal and state “regulatory drivers” thatinfluence watershed restoration, including thealphabet soup of TMDLs, MS4 NPDESPermits, CSO, SSO, SWDA, ESA, FEMA,among others. The second part analyzesexisting municipal capabilities and resourcesfor watershed restoration. This usually entailsan agency-by-agency review of existing staff,programs, funding and mapping resources thatcan potentially be applied to watershedrestoration. Both assessments are bestconducted on a watershed-wide or municipalscale, in cooperation with regionalstakeholders.

Existing Data Analysis (EDA) This taskanswers the question: “What is already knownabout the watershed?” In many cases, a wealthof watershed monitoring and mapping data hasbeen produced over the years, which can helpdefine critical water resource problems.Consequently, this task involves an extensiveanalysis of historical water quality andbiological monitoring data within thewatershed, as well as a search for any availablemapping and GIS resources. While good

watershed information usually exists, thechallenge is to locate it and critically evaluateits quality. The data analysis usually requiresan intensive search of academic institutions,federal databases, regional GIS centers, stateand local agencies, and non-governmentalorganizations. If sound data is not available,then additional monitoring or research may beneeded to establish goals. The end product is abaseline assessment that describes waterquality and habitat problems across thewatershed or municipality.

Achieving Stakeholder Consensus (ASC)Goal-setting requires extensive stakeholderinput to identify important community interestsand issues that will drive the watershedrestoration effort. Under this task, forums arecreated to find out what the public thinks abouturban watersheds and what issues they wantincorporated in the restoration plan. Recurringissues include recreation, greenways, flooding,waterfront and neighborhood revitalization,enforcement, and cleanups, in addition to waterquality and habitat. By listening to all fourgroups of stakeholders, it is possible to gainbroad agreement on the overall goals that willdrive local watershed restoration efforts.

Watershed Goals and Objectives (WGO) Themanagement product of this task is thedefinition of clear, measurable goals thatcommand broad public support to guide thewatershed restoration process. Assuming thatconsensus on these goals can be reached, it ishelpful to produce a watershed agreement, amemorandum of understanding or similardirective that establishes interim goals forwatershed restoration that can be executed byelected officials, key stakeholders and/or senioragency leaders. These agreements can raise theprofile of watershed restoration and ensuregreater inter-agency coordination later in theprocess.



Step 2: Screen for PriorityStep 2: Screen for PriorityStep 2: Screen for PriorityStep 2: Screen for PriorityStep 2: Screen for PrioritySubwatershedsSubwatershedsSubwatershedsSubwatershedsSubwatersheds

The second step of the framework selectspriority subwatersheds within the watershedthat show the most promise for effectiverestoration. This step can be skipped if thesubwatershed(s) have already been selected.

Comparative Subwatershed Analysis (CSA)It is relatively easy to quickly screen the mostpromising subwatersheds from a desktop,assuming that basic GIS layers are available.The first step is to subdivide the watershed todelineate subwatersheds that are typicallyabout one to five square miles in area. In thesecond step, important stream corridor andsubwatershed metrics are derived from GISdata to “discriminate” among subwatersheds.At the stream corridor level, key metricsinclude channel density, stream corridor area,and stream assessment data. For upland areas,key variables include the subwatershedimpervious cover, public land, detachedresidential housing, industrial lands, naturalarea remnants, and the presence or absence ofstorm water practices. Each of these factorscan be weighted and analyzed in a simplespreadsheet model to rank the comparativerestoration potential for each subwatershed.

Rapid Baseline Assessment (RBA) Somecommunities may want to collect moremonitoring data to characterize water quality,habitat or biological conditions across itssubwatersheds, although this can be bothexpensive and time-consuming. The basicapproach is to establish a network of fixedstations where stream parameters are rapidlymeasured to indicate current aquatic health

within all subwatersheds. These subwatershed“indicators” can be used to track how a streammay respond to future subwatershed restorationefforts. Examples include the Rapid StreamAssessment Technique (RSAT), RapidBioassessment Protocol (RBP), dry or wetweather water quality sampling, and fishshocking. The basic objective of a baselineassessment is to get data within a few monthsthat can be incorporated into the comparativesubwatershed analysis.

Restoration Education and Outreach (REO)Once again, it is important to involve keystakeholders in the process of choosing prioritysubwatersheds, since strong public support isoften instrumental in successful restoration(particularly when organized community orwatershed groups exist). Effective watershedoutreach efforts at this stage includeworkshops, community meetings, field trips, andwatershed maps. Efforts should be made tocondense watershed issues into an accessibleand understandable format. Watershedoutreach efforts can increase publicunderstanding about local watershed problems,set realistic expectations and may even recruitnew stakeholders to the cause. Stakeholderscan also play a role in devising the weightingfactors for subwatershed ranking to maximizeoverall support.

Priority Subwatershed List (PSL) Themanagement product associated with this stepis simple: a decision on which subwatersheds towork on first. It is often helpful to produce atechnical memo documenting the rankingsystem used to derive the priority subwatershedlist to justify why restoration efforts are beingdeferred in other subwatersheds.



Step 3: Evaluate RestorationStep 3: Evaluate RestorationStep 3: Evaluate RestorationStep 3: Evaluate RestorationStep 3: Evaluate RestorationPPPPPotentialotentialotentialotentialotential

The third step is a systematic assessment ofpotential restoration opportunities within thestream corridor and subwatershed, andinvolves five important tasks.

Detailed Subwatershed Analysis (DSA) It isimportant to compile basic subwatershedinformation and generate base maps for streamcorridor and subwatershed assessments prior togoing out in the field. This first phase ofdesktop analysis characterizes currentsubwatershed characteristics, plans routes andestablishes stream survey reaches. Extra timespent in the office can save a lot of time out inthe field. The second phase of desktop analysisoccurs after the field assessments andstakeholder involvement tasks are completed.This phase assembles, implements and analyzessubwatershed data to devise an initialrestoration strategy.

Unified Stream Assessment (USA) The USAis a rapid assessment of all surface drainage ina subwatershed to identify problems andrestoration opportunities within the streamcorridor. The USA evaluates eight streamimpacts or conditions, including storm wateroutfalls, severe erosion, impacted buffers, utilitycrossings, trash and debris, stream crossings,channel modifications, and miscellaneousfeatures. The running survey relies on GPSmapping, digital photos and reach analysis toidentify potential sites for individual retrofit,stream restoration, discharge prevention orriparian management projects. The datacompiled from USA surveys is then analyzed toevaluate the restoration potential of the streamcorridor (see Manual 10).

Unified Subwatershed and SiteReconnaissance (USSR) The USSR is acompanion survey that explores pollutionsources and restoration opportunities in theupland areas of a subwatershed. During aUSSR survey, a team drives all roads in thesubwatershed, evaluates neighborhoodconditions, and assesses all open spaces largerthan two acres. The USSR profiles currentpractices in residential neighborhoods, thecondition of streets and storm drains, and thepotential for on-site retrofits. It is also used toconfirm the location and severity of stormwater hotspots. Finally, the USSR creates aninventory of upland sites for potentialreforestation or natural area restoration. Datacollected from the USSR is then analyzed toevaluate strategies such as improved retrofits,source control, pervious area management andmunicipal practice in the subwatershed.

Stakeholder Identification and Recruitment(SIR) In this task, all of the potentialstakeholders that live or work in thesubwatershed are identified, a group that mayinclude individuals from civic groups, churches,neighborhood associations, schools, institutionallandowners, businesses, and otherorganizations. These individuals should beactively recruited to participate in futurestakeholder meetings. Some stakeholders canbe identified during the USSR, but additionalnetworking is usually needed to get the rightpeople to the table.

Initial Subwatershed Strategy (ISS) This stepproduces a great deal of initial data onrestoration options and opportunities in thesubwatershed. The management product forthis step is a quick analysis of subwatersheddata to devise an initial restoration strategy.This initial strategy is often accompanied by ascope of work outlining detailed restorationinvestigations to pursue in subsequent steps.



Step 4: Conduct DetailedStep 4: Conduct DetailedStep 4: Conduct DetailedStep 4: Conduct DetailedStep 4: Conduct DetailedRestoration AssessmentRestoration AssessmentRestoration AssessmentRestoration AssessmentRestoration Assessment

The fourth step of the framework involvesassessing the feasibility of individualrestoration projects in the subwatershed orstream corridor.

Project Concept Design (PCD) This desktoptask develops detailed concept designs forindividual restoration projects identified duringthe initial subwatershed restoration strategy.Project data from detailed site investigations isthen used to work up concept designs for themost feasible and effective restoration projectsin the subwatershed. Some upland restorationpractices, such as source control and municipalpractices, are developed and refined at thedesktop level. Each candidate project is thenevaluated with regard to feasibility, designconstraints, estimated cost and potentialrestoration benefits. Planning and designinformation for individual restoration projectsare then organized into spreadsheets and/orGIS for subsequent analysis in the next step.

Candidate Project Investigations (CPI) Thistask gathers the field and/or engineering dataneeded to develop workable concept designsfor individual restoration projects in the streamcorridor. Depending on the initial restorationstrategy, this may entail one or more of thefollowing:

· Retrofit Reconnaissance Inventory (RRI)· Stream Repair Investigation (SRI)· Riparian Management Inventory (RMI)· Discharge Prevention Investigation (DPI)

These investigations are used to acquire enoughdata to develop a basic concept design for eachrestoration project.

These investigations are vital to developworkable plans or programs to control uplandpollutant sources and/or restore pervious areasin the subwatershed. Depending on the initialrestoration strategy, this may entail one or moreof the following investigations:

· Hotspot Compliance Inspections (HCI)· Natural Area Remnant Analysis (NARA)· Watershed Reforestation Inventory (WRI)· Source Control Plan (SCP)· Municipal Operations Analysis (MOA)

These rapid investigations are used to eitherdevelop a basic concept design for each projector determine effective program delivery.

Managing Stakeholder Input (MSI) The firstcommunity stakeholder meeting should reporton the early results of subwatershed analysesand get initial feedback from the “nighttime”stakeholders that live and work in thesubwatershed. While evening meetings are acommon way of soliciting involvement, othermethods such as Saturday subwatershed tours,websites, mailings, or stream walks can also beused to solicit involvement. All of theseinvolvement methods can help elicit the issuesand concerns stakeholders want to incorporateinto the subwatershed plan.

Inventory of Restoration Opportunities(IRO) The management product associatedwith this step is an inventory of feasiblerestoration projects for the subwatershed thataddresses restoration goals and objectives setat the watershed level.



Step 5: Assemble ProjectsStep 5: Assemble ProjectsStep 5: Assemble ProjectsStep 5: Assemble ProjectsStep 5: Assemble Projectsinto Planinto Planinto Planinto Planinto Plan

The fifth step transforms the restorationinventory into a draft subwatershed plan thatrecommends the most cost-effectivecombination of restoration projects andprograms to meet subwatershed goals. Keytasks of this step include project ranking,neighborhood consultation and plan writing.

Project Evaluation and Ranking (PER) Thistask involves a detailed evaluation and rankingof the whole range of projects and programs inthe restoration inventory. Each project or groupof projects is ranked according to subwatershedarea treated, cost, feasibility, environmentalbenefits, public acceptance and other keyimplementation factors. The exact rankingfactors and their corresponding weights areunique to each subwatershed and should reflectoverall restoration goals and stakeholder input.The ranking is typically done throughspreadsheet analysis, and the results are usedto select the package of projects to recommendfor final design. In some cases, additional fieldsurvey or subwatershed data may be needed tosupport project evaluation.

Neighborhood Consultation Meetings(NCM) Storm water retrofits and otherrestoration products can significantly alter alocal landscape that has been around foryears. Residents often have legitimateconcerns about access, safety, mosquitoes,weeds, vermin, tree loss and other issuesrelated to a particular restoration project.Consequently, it is wise to get input fromadjacent stakeholders and respond to theirconcerns early in the design process. Forumsand field trips to notify adjacent residentsabout proposed projects are always a goodinvestment.

Draft Subwatershed Plan (DSP) Themanagement outcome of this task is a concisesubwatershed plan with specificrecommendations for implementingrestoration projects and programs, along witha subwatershed management map. A goodsubwatershed plan need not be long orcomplex. Instead, it should be written withthe punch of a newspaper article, and clearlyspecify the “what,” “why,” “when,” “where,”and “how much” of the recommendedcombination of restoration projects.



Step 6: Determine WhetherStep 6: Determine WhetherStep 6: Determine WhetherStep 6: Determine WhetherStep 6: Determine WhetherSubwatershed Plan MeetsSubwatershed Plan MeetsSubwatershed Plan MeetsSubwatershed Plan MeetsSubwatershed Plan MeetsWWWWWatershed Goalsatershed Goalsatershed Goalsatershed Goalsatershed Goals

This is perhaps the most frequently overlookedstep in watershed restoration: determiningwhether or not the subwatershed plan can meetwatershed goals. In some cases, models andpredictive tools to make this determinationmay not exist. In these cases, plan success canonly be measured by future monitoring in thesubwatershed, and the subwatershedrestoration plan becomes its own experiment.In other cases, however, predictive models canbe used to determine whether the plan willmeet restoration goals. Some communities mayelect to pursue this step concurrently with thedevelopment of the draft subwatershed plan.

Subwatershed Treatment Analysis (STA) Ifwatershed restoration goals are oriented towardhydrology or water quality, there are severalgood desktop models for estimating the plan’swatershed treatment and associated pollutantreduction. Manual 2 describes how to apply theWatershed Treatment Model (WTM) toquantify the pollutant reduction achieved by thesubwatershed restoration plan, and providesreferences for other subwatershed assessment

tools. Fewer predictive models exist toevaluate restoration goals geared to improvinghabitat or aquatic biodiversity.

External Plan Review (EPR) An importantelement of plan evaluation is review and inputfrom the subwatershed stakeholders, whohelp ensure the plan meets the unique needsof both the subwatershed and the community.Generally, review of the draft plan involves atleast one additional stakeholder meeting.

Subwatershed Implementation Strategy(SIS) It is extremely useful during this step tobegin thinking about what it will take to getthe plan adopted and how it might be fundedover time. Since watershed plans competeagainst many other municipal expenditures, itis helpful to develop an implementationstrategy for navigating the plan through thepolitical and bureaucratic system. Twomanagement tasks are associated with thisstep. The first is to make a persuasive casethat the subwatershed plan is worth thecommunity investment, and the second is tocreate an organized campaign for presentingthat case to the influential members of thecommunity. This campaign should targetelected officials, regulators, local media, stateand federal funders, and the activist public.



Step 7: Implement PlanStep 7: Implement PlanStep 7: Implement PlanStep 7: Implement PlanStep 7: Implement Plan

This step deals with the many complex tasksinvolved in the final design, public review andadoption of the plan.

Final Design and Construction (FDC) Muchof the time and expense in the subwatershedplanning process is expended for the finaldesign, engineering and permitting of individualrestoration projects. Since many differentprojects and programs will be implemented inthe subwatershed plan, you will need toanticipate how to “deliver” restoration projects(i.e., how to sequence design, construction,inspection, maintenance and monitoring withinbudget constraints). Particular emphasis shouldbe placed on getting the most accurate projectcost estimates possible, so that the total cost ofthe plan can be established and phased overtime.

Engineering Design Surveys (EDS) Thisround of surveys is used to acquire enoughdata to directly support the final design,permitting and installation of restorationpractices. The exact type and number ofsurveys needed depends on the type ofrestoration practice and the conditions at the

project site. In general, stormwater retrofits andstream repairs require the greatest number ofengineering and design surveys. Commonexamples include geotechnical surveys, wetlanddelineations, topographic surveys, forest standdelineations and construction inspections.

Creating Restoration Partnerships (CRP)While it may seem redundant to have anotherround of stakeholder involvement, it is importantto get formal support and endorsement of thefinal plan. The goal is to transform stakeholdersinto partners, and create a broad communitycoalition to attract the political support neededto get reliable funding for plan implementation.

Adopt Final Plan (AFP) There is no universalmethod for final plan adoption, given that thepolitical process, partnership structure, andbudgetary system are unique in everycommunity. The basic management product inthis step is to work through the existing processto adopt the plan, and define a short- and long-term funding strategy to implement it. It isimportant to keep in mind that manycommunities cannot obligate operating fundsbeyond the current budget year (although theymay be able to sequence capital projects over alonger time frame).



Step 8: MeasureStep 8: MeasureStep 8: MeasureStep 8: MeasureStep 8: MeasureImprovements Over TimeImprovements Over TimeImprovements Over TimeImprovements Over TimeImprovements Over Time

Urban restoration is such a new field that eachrestoration plan is basically its own experiment.As a result, it is important to institute trackingand monitoring systems to measureimprovements in subwatershed indicators overtime. These systems can include internallytracking the delivery of restoration projects in asubwatershed, as well as monitoring streamindicators at sentinel monitoring stations.Performance monitoring of individualrestoration projects can be tracked to improvethe design of future restoration practices.Information gathered from each of thesetracking systems is used to revise or improvethe restoration plan over a five- to seven-yearcycle.

Tracking Project Implementation (TPI) Fewpeople fully comprehend the complexity ofdelivering a large group of restoration projectswithin a small subwatershed. It is a good ideato use a spreadsheet or GIS system to trackproject implementation data such as projectconstruction, inspection, maintenance andperformance. Project tracking data chroniclesprogress made in subwatershedimplementation, and can isolate managementproblems to improve the delivery of futurerestoration projects.

Sentinel Monitoring Stations (SMS) In thistask, fixed, long-term sentinel stations areestablished to measure trends in selectedaquatic indicators over many years (preferablyat the same locations monitored during theinitial baseline assessment). Sentinel monitoringis perhaps the best way to determine howstreams are actually responding tosubwatershed restoration. Few communitieshave the resources to continuously maintain along-term monitoring program, but the existence

of sentinel stations ensures that the rightindicators are measured at the same placeswhen money is available for monitoring.

Performance Monitoring of Practices (PMP)Restoration practices are often experimental,and it is important to measure whetherrestoration projects are really working as theywere designed to. As a result, communities maywant to invest in performance monitoring ofindividual restoration projects to improve futuredesigns. Such monitoring can be relativelysimple (observing the success of a reforestationproject) or extremely complex and expensive(measuring the pollutant reduction of a stormwater retrofit or the biological response to acomprehensive stream restoration project).

Ongoing Management Structure (OMS) Fullimplementation of subwatershed restorationplans usually takes a minimum of five years,and often as many as 10. Therefore, it is criticalto find a way to sustain momentum forsubwatershed restoration over such anextended period. The preferred method is tocreate a small watershed organization orinteragency committee to advocate for the planand handle ongoing education, outreach andpublic involvement tasks. Ideally, such a groupshould be created much earlier in the process(or may have already existed). The key point isthat the watershed advocacy function must besustained and supported throughout theimplementation stage, and often well beyond.

Adapt Subwatershed Plan (ASP) Themanagement outcome of this step is fairlysimple: a measurable improvement in theindicators used to define subwatershed quality.If expected improvements have not occurred, are-assessment of either the subwatershedrestoration plan or expectations for meetingwatershed goals may be required.



SummarSummarSummarSummarSummaryyyyy

This chapter presents an ideal framework toguide and organize the small watershedrestoration planning process. In reality, everycommunity will end up with its own peculiarplanning process reflective of its diversewatersheds, unique goals, funding sources,partners and prior experience. The key point isthat each community should develop a clearand understandable process to translate plansinto action. The next manual, Methods toDevelop Restoration Plans for Small UrbanWatersheds, presents different options to helpcreate an effective planning process.



Urban Subwatershed Restoration Manual 1 A-1

Appendix A: Derivation of Predictions for the Impervious Cover Model

Appendix AAppendix AAppendix AAppendix AAppendix A::::: Derivation of PDerivation of PDerivation of PDerivation of PDerivation of Predictions forredictions forredictions forredictions forredictions forthe Imperthe Imperthe Imperthe Imperthe Impervious Cover Modelvious Cover Modelvious Cover Modelvious Cover Modelvious Cover Model

The third chapter of this manual presentsquantitative predictions as to how 22 specificstream corridor indicators behave in thecontext of the Impervious Cover Model (ICM).These general predictions are intended todiagnose the severity of stream impacts, setrealistic goals for restoration, and plan anddesign restoration practices in the streamcorridor.

This Appendix outlines the current researchsupporting the ICM, with particular referenceto the impacted (I), non-supporting (NS) andurban drainage (UD) stream categories. Itbegins with a general discussion about thelimitations and caveats of the ICM, and thenexplores how specific quantitative or narrativepredictions were derived for each of the 22stream corridor indicators. The sectiondescribes how each indicator was defined,measured or computed, and the baselinecondition against which it is compared. Next,the research, models, and other evidence usedto support predictions are described. Remarksare also made about the utility of eachindicator in urban subwatershed restorationplanning and design.

Lastly, we comment on our confidence in theaccuracy and reliability of the individualindicator predictions of the ICM. In somecases, the predictions are merely untestedhypotheses, while others are solidly groundedin science and engineering. Where possible,we recommend ways these predictions couldbe improved or narrowed through furtherurban subwatershed research.

This appendix is organized into seven sections:

A. Summary of the ICM and its Use inSubwatershed Restoration Planning

B. Derivation of Hydrologic Predictions forthe ICM

C. Derivation of ICM Predictions for PhysicalAlteration of the Urban Stream Corridor

D. Derivation of Urban Stream HabitatPredictions for the ICM

E. Derivation of Urban Water QualityPredictions for the ICM

F. Derivation of Aquatic DiversityPredictions for the ICM

G. Summary

AAAAA: Summar: Summar: Summar: Summar: Summary of the ICM and itsy of the ICM and itsy of the ICM and itsy of the ICM and itsy of the ICM and itsUse in Subwatershed RUse in Subwatershed RUse in Subwatershed RUse in Subwatershed RUse in Subwatershed RestorationestorationestorationestorationestorationPlanningPlanningPlanningPlanningPlanning

The ICM organizes a series of testablehypotheses about how stream corridorindicators respond to greater subwatershedimpervious cover (IC). It is used to classifythree types of urban streams based onsubwatershed IC: impacted, non-supportingand urban drainage. We have not included anypredictions for sensitive streams (that have lessthan 10% IC), because they do not meet ourdefinition of urban subwatershed, and are oftenpredicted better by other subwatershed metrics(CWP, 2003).

The ICM applies to small streams, from first tofourth order, with a contributing subwatershedarea of less than 10 square miles. ICMpredictions are general, and may not apply toevery stream within the proposedclassifications. Urban streams are notoriouslyvariable, and factors such as gradient, streamorder, stream type, age of subwatersheddevelopment, and past land use can and willmake some streams depart from thesepredictions. Indeed, these “outlier” streams are

Urban Subwatershed Restoration Manual 1A-2


extremely interesting from the standpoint ofrestoration. In general, subwatershed ICcauses a continuous but variable decline inmost stream corridor indicators. Consequently,the severity of individual indicator impactstends to be greater at the upper end of the ICrange for each stream category.

The ICM does not explicitly address theinfluence of past subwatershed treatment or theeffect of future subwatershed restorationpractices. This is not currently much of alimitation since few urban subwatersheds havebeen comprehensively treated and/or restoredto date. Indeed, Manual 2 presents a sequenceof monitoring and modeling methods tomeasure how individual stream indicatorsmight respond to subwatershed treatment.

It should also be noted that limited evidenceexists to define indicator behavior in the upperrange of NS stream category and the entire UDcategory. More systematic research is neededon these highly urban streams, which havereceived scant attention despite the fact theyare the most polluted, impaired and degradedof any stream category.

For comparative purposes, a baseline conditionis provided to give a general sense of themaximum possible improvement in theindicator that might be achieved bysubwatershed restoration (although this degreeof improvement cannot be attained in all urbansubwatersheds). The baseline condition helpsassess and quantify realistic goals andobjectives for subwatershed restoration. Ingeneral, the baseline condition is defined as astream located in a rural subwatershed in goodcondition. Rural land use is considered to be asubwatershed that contains a mix of forest,pasture, and crops; has not experiencedextensive channel modification; has an intactriparian forest buffer; and lacks major pointsources of pollution.

Lastly, while the ICM is quite useful, it isobviously not the only factor to consider inurban subwatershed restoration planning. Othersubwatershed metrics, such as turf or perviouscover, stream corridor condition, age andcondition of sewer system, stream interruption,

hotspot density, and age of development are allextremely useful to define opportunities andconstraints for subwatershed restoration.

B: Derivation of HydrologicB: Derivation of HydrologicB: Derivation of HydrologicB: Derivation of HydrologicB: Derivation of HydrologicPPPPPredictions for the ICMredictions for the ICMredictions for the ICMredictions for the ICMredictions for the ICM

1. Influence of Storm W1. Influence of Storm W1. Influence of Storm W1. Influence of Storm W1. Influence of Storm Water Rater Rater Rater Rater Runoffunoffunoffunoffunoff

Definition and measurement of indicatorThis indicator is defined by the subwatershedrunoff coefficient or Rv, which measures thefraction of annual rainfall volume that isconverted into storm water runoff. It ismeasured by simultaneously sampling thevolume of rainfall and storm water runoffproduced at a single catchment over multiple(20+) storm events.

Baseline condition The annual volume ofstorm water runoff produced by anundeveloped rural subwatershed. Prior researchhas established that the Rv ranges from 0.02 to0.07, depending on soils, slope and geology ofthe rural subwatershed monitored.

Reference used to derive The Rv vs. ICrelationship is presented in Figure 1.2 inSchueler (1987), which examined 44 urbancatchments monitored in the U.S. during theEPA NURP program.

Utility in restoration planning and designThe Rv is a fundamental indicator of the degreeof hydrologic alteration within a subwatershed,and is also used to estimate pollutant loadings(which are a direct function of subwatershedIC). The Rv relationship is also used in retrofitdesign to estimate the size and storage volumerequired for these practices.

Comments The Rv vs. IC relationship is welldocumented, and has been directlyincorporated into many widely-usedengineering hydrology models.

2. Flood Plain Expansion2. Flood Plain Expansion2. Flood Plain Expansion2. Flood Plain Expansion2. Flood Plain Expansion

Definition and computation of indicatorThis indicator is defined as the ratio of the



current peak discharge rate to the pre-development peak discharge rate producedduring a 100-year rainfall event at a specificpoint of interest within the subwatershed(expressed in units of cubic feet per second, orcfs). This ratio is a useful index of the probableexpansion of the flood plain within the existingstream corridor. In practice, the ratio iscomputed by applying detailed hydrologymodels to estimate the peak discharge rates forcurrent conditions, which are a function ofcurrent subwatershed IC, soil types, andhydraulic conditions in the stream channel andflood plain. The models are then run again tosimulate pre-development conditions in thesubwatershed, and the ratio of the two currentand pre-development peak discharge rates isthen computed.

Baseline condition compared to The 100-year peak discharge rate for pre-developmentconditions is usually modeled assuming thesubwatershed has a rural land use mix (e.g.,forest, pasture and crops) and does not have astorm drain collection system. For comparisonpurposes, the index or ratio for an undevelopedrural subwatershed is one.

References used to derive Sauer et al. (1983)and Hollis (1975) established the initialrelationship. The basic modeling tools topredict 100-year peak discharge rates for pre-development and current developmentconditions have advanced considerably sincethen, but the newer hydrologic models stillgive the same basic results in most urbansubwatersheds (USGS, 1996).

Utility in restoration planning and designThe index helps define the degree of flood plainexpansion in the stream corridor. High indexvalues indicate that flooding problems may besevere in the stream corridor, and could suggestthat older stream crossings may lack sufficientcapacity to handle increased flood waters. Thepeak discharge ratio also helps estimate themaximum stress and current velocities thatstream repair practices will be exposed to.

Comments The relationship between IC and100-year peak discharge rate ratios arereasonably well established, but several other

subwatershed factors can also stronglyinfluence this indicator. These factors includethe type and age of storm drains, the age ofsubwatershed development, and the existinghydraulic capacity of both the stream channeland its flood plain.

3. Bankfull Flooding F3. Bankfull Flooding F3. Bankfull Flooding F3. Bankfull Flooding F3. Bankfull Flooding Frequencyrequencyrequencyrequencyrequency

Definition and computation of indicatorThis indicator is defined as the number of flowevents that completely fill the cross-sectionalarea of the pre-development channel in anaverage year of rainfall. Continuous hydrologicsimulation models are often used to derive thisstatistic, by comparing bankfull floodfrequency based on current subwatershedconditions against the frequency computed forassumed rural, pre-development conditions.

Baseline condition compared to In ruralwatersheds, the bankfull flood frequency isabout 0.5 events per year, or roughly onebankfull flood event every two years.

References used to derive The basicrelationship was developed by Leopold (1968,1994) and a simple model to relate bankfullflooding frequency to subwatershed IC wasadvanced in Figure B-3, Appendix B “BankfullFlooding Frequency Analysis” by Schueler(1987). Data from Konrad and Booth (2002)and Nehrke and Roesner (2002) were alsohelpful in characterizing the relationship.

Utility in restoration planning and designThis indicator helps assess the potential severityof stream bank erosion and habitat degradationwithin an urban subwatershed. Bankfullflooding frequency can also be reduced whenupstream storage retrofits are constructedwithin a subwatershed, so it is often used toplan the location and required storage ofupstream storm water retrofit practices toprotect the channel. In addition, bankfullflooding frequency has considerable value instream repair design.

Comments The actual bankfull discharge canchange over time in an urban subwatershed, asthe cross-sectional area of the stream channelgradually enlarges to accommodate increased



storm water flows (see indicator # 7).Therefore, this indicator will be less accurate inolder subwatersheds where channel incisionand enlargement have already increased thecapacity of the channel to accommodate pre-development bankfull flood discharge rates.Stream order may also be important in definingbankfull flooding frequency in urban streams.Palmer et al. (2003) observed the greatestincrease in bankfull flooding frequencyoccurred in first and second streams, and wasattenuated to some degree in third and fourthorder streams.

C: Derivation of ICM PC: Derivation of ICM PC: Derivation of ICM PC: Derivation of ICM PC: Derivation of ICM Predictionsredictionsredictionsredictionsredictionsfor Physical Alteration of thefor Physical Alteration of thefor Physical Alteration of thefor Physical Alteration of thefor Physical Alteration of theUrban Stream CorridorUrban Stream CorridorUrban Stream CorridorUrban Stream CorridorUrban Stream Corridor

4. Stream Enclosure/Modification4. Stream Enclosure/Modification4. Stream Enclosure/Modification4. Stream Enclosure/Modification4. Stream Enclosure/Modification

Definition and measurement of indicatorThis indicator is defined as the fraction of thepre-development stream network that remainsintact, expressed in terms of total length(miles) or stream density (miles/square mile).This indicator is derived by comparing thelength of the historical stream network (derivedfrom historical maps or photos) to its currentstream length (determined from GIS analysis orfield assessment).

Baseline condition compared to Ruralstreams that have 90 to 100% of the originalstream network remaining, although some mayhave experienced greater modification becauseof past agricultural drainage, flood control orchannelization “improvements.”

References used to derive The predictionsare primarily based on anecdotal evidence,although several studies have documented thatindividual urban subwatersheds loseconsiderable stream density at high levels ofdevelopment (Dunne and Leopold, 1978 andNVRC, 2001). As a practical consideration,very few biological or habitat indicators arereported above 50 to 60% subwatershed IC,which indirectly suggests that this level of ICmay be the breakpoint where natural streamchannels are enclosed or channelized.

Utility in restoration planning and designThis indicator can help define generalopportunities to daylight streams, and is also agood measure of the loss of headwater streamsthat are important in stream ecology.

Comments The age and intensity ofdevelopment in a subwatershed can also bevery important in defining this stream corridorindicator. For example, recently developedsubwatersheds could potentially be subject toless stream enclosure/modification because ofwetland permitting and/or stream bufferrequirements.

5. Riparian F5. Riparian F5. Riparian F5. Riparian F5. Riparian Forest Continuityorest Continuityorest Continuityorest Continuityorest Continuity

Definition and measurement of indicatorThis indicator is defined as the fraction of theexisting perennial stream network thatpossesses an intact forest buffer of anappropriate width (e.g., 50 feet on either sideof channel). Riparian forest continuity, or RFCcan be directly measured by the Unified StreamAssessment (Manual 10) or through a GISanalysis of aerial photographs of asubwatershed.

Baseline condition compared to Ruralstreams typically have an intact riparian forestbuffer along about 80 to 100% of their streamcorridor, according to regional surveys byJones et al. (1997). Riparian forest continuity,however, can be quite variable in some ruralsubwatersheds, depending on the prevailingriparian management practices used byadjacent farmers and ranchers.

References used to derive Only one study hasdefined the behavior of RFC over a broadrange of subwatershed IC (Horner et al., 1997),but the Center has consistently seen the sharpdecline in RFC during field work in highlyurban subwatersheds.

Utility in restoration planning and designRiparian forest continuity is an extremelyimportant indicator of subwatershed with highpotential to reforest or improve management ofthe stream corridor. RFC is also a goodindicator to measure progress made in riparianreforestation at the subwatershed level.



Comments Historical stream corridormanagement actions can also be extremelyimportant to explain RFC behavior withinindividual subwatersheds. For example, pastdecisions to locate stream valley parks,regulate the flood plain or require streambuffers during development can all stronglyinfluence RFC.

6. Stream Interruption6. Stream Interruption6. Stream Interruption6. Stream Interruption6. Stream Interruption

Definition and measurement of indicatorThis indicator is defined as the average numberof stream crossings per stream mile in asubwatershed, and can be measured during theUnified Stream Assessment (Manual 2) orthrough careful GIS analysis of subwatershedaerial photos.

Baseline condition compared to Ruralstreams usually have less than one crossing perstream mile, according to an extensive nationalGIS watershed analysis by Jones et al. (1997).

References used to derive Only one study hasexplored the relationship between IC and thenumber of stream crossings in urbansubwatersheds (May et al., 1997), although ourfield experience, drawn from many urbanwatershed assessments, suggests that it is arobust relationship.

Utility in restoration planning and designThe number of stream crossings can be used todetermine urban fishery resource potential,with an emphasis on the potential severity ofbarriers to fish migration in a subwatershed. Inaddition, the number of hard crossings can beuseful to locate potential storage retrofit sitesin the stream corridor, and to identify existinggrade controls that may locally moderatestream bank erosion in the stream network.

Comments While that this indicator relationshipseems robust, it has not been systematicallystudied across the full range of IC, particularlyin the NS and UD categories. Indeed, streamcrossings are probably irrelevant in UDsubwatersheds, for the simple reason that thereare no streams left to cross.

D: Derivation of UrbanD: Derivation of UrbanD: Derivation of UrbanD: Derivation of UrbanD: Derivation of UrbanStream Habitat PredictionsStream Habitat PredictionsStream Habitat PredictionsStream Habitat PredictionsStream Habitat Predictionsfor the ICMfor the ICMfor the ICMfor the ICMfor the ICM

7. Channel Enlar7. Channel Enlar7. Channel Enlar7. Channel Enlar7. Channel Enlargement Rgement Rgement Rgement Rgement Ratioatioatioatioatio

Definition and measurement of indicatorThis indicator of expected channel enlargementis defined as the ratio of the ultimate streamchannel cross-sectional area compared to thepre-development cross-sectional area, averagedfor multiple stream reaches in a subwatershed.Channel enlargement can be measured, if bothcurrent and historical cross-sectional data areavailable for stream channels, and can bemodeled if extensive geomorphic data isavailable.

Baseline condition compared to A ruralstream of the same geomorphic type that hasstable banks, which is defined as having a ratioof one.

References used to derive The basicrelationship has been proposed by Caraco(2001); MacRae and DeAndrea (1999);MacRae (1996); and Hammer (1972). BothBledsoe (2001) and Booth and Henshaw(2001) observed that the power of IC to predictstream channel enlargement is not particularlygreat at low to moderate levels ofsubwatershed development (5 to 15% IC), andargued that many other subwatershed andgeomorphic variables complicate theenlargement prediction in these subwatersheds.On the other hand, the Center’s fieldassessments clearly indicate that progressivelygreater bank instability and enlargement arecommon for both the NS and UD streamcategories.

Utility in restoration planning and designThe channel enlargement indicator is a goodindex of bank stability along the stream corridor,as well as the likely degree of habitatimpairment in the stream. A generalunderstanding of expected channel enlargementis also quite helpful when designing streamrepair and restoration practices.



Comments More research is needed to assessthe degree of channel enlargement that occursin the NS and UD stream categories. It is alsoquite likely the age of development will be animportant subwatershed factor, since thechannel enlargement process may take decadesto fully manifest itself in many urban streams.

8. Sediment Supply to Stream8. Sediment Supply to Stream8. Sediment Supply to Stream8. Sediment Supply to Stream8. Sediment Supply to Stream

Definition and measurement of indicatorThe indicator is defined by the ratio of theannual sediment yield produced from an urbansubwatershed compared to a rural one,expressed in terms of mass per unit area peryear (e.g., tons/square mile/yr). The sedimentyield indicator reflects the delivery of greaterurban sediment loads caused by acceleratedstream bank and channel erosion. Long-termsediment and flow monitoring are needed tocompute the subwatershed sediment yield,which has been done at a few smaller USGSgage sites.

Baseline condition compared to A stablerural stream of the same geomorphic type andsubwatershed area.

References used to derive The fact thatindividual urban subwatersheds have higherunit area sediment yields compared to ruralsubwatersheds has been established by Barton(2003); Trimble (1997); and Dartiguenave etal. (1997). To date, no studies have tracked thisindicator over the broad range of imperviouscover encompassed by the ICM. In addition,the potential for reduced urban sediment yieldsbecause of extensive stream enclosure/modification has not been investigated, butcould be very important in UD subwatersheds.

Utility in restoration planning and designThis indicator is important to assess asubwatershed’s contribution to downstreamsediment loads, as well as predicting internalsediment dynamics within the stream channel.Sediment yield can be used to forecast thefuture loss of capacity in storage retrofits andstream repair practices due to sedimentdeposition.

Comments The general prediction isreasonably strong, but is complicated by theevolution process of urban stream channels.More research on the unit area sediment yielddata over the range of IC covered by the ICMwould be helpful, particularly for channels thatare naturally adjusting and those that arechannelized/enclosed.

9. T9. T9. T9. T9. Typical Stream Habitat Scoreypical Stream Habitat Scoreypical Stream Habitat Scoreypical Stream Habitat Scoreypical Stream Habitat Score

Definition and measurement of indicatorThis indicator is defined by the average streamhabitat score sampled in multiple streamreaches in an urban subwatershed, compared toa rural subwatershed. Stream habitat scores arefrequently measured by the EPA rapid habitatassessment protocol (Barbour et al., 1999) orequivalent habitat assessment method.

Baseline condition compared to A ruralstream in good condition (i.e., with stable banksand intact riparian zone) typically has “good” or“very good” habitat index scores. As Wang etal. (2001) notes, however, habitat scores maybe lower in some rural streams with poorriparian management practices.

References used to derive A detailed reviewof the general relationship between IC andstream habitat is provided in CWP (2003). Moststream researchers have only looked at therelationship between 5 and 25% subwatershedIC (Morse 2001 and Wang et al. 2001).Consequently, very little systematic data isavailable to characterize stream habitat qualitywithin the upper range of the NS streams andthe entire UD category. Once again, theCenter’s field assessments indicate that habitatquality is consistently poor to very poor inthese streams.

Utility in restoration planning and designIn-stream habitat scores are a useful indicatorto assess fishery restoration potential in urbansubwatersheds, and can be used to trackrestoration progress.

Comments More subwatershed research isneeded to characterize habitat quality in NSand UD streams in order to refine thepredictions.



10. P10. P10. P10. P10. Presence of Lresence of Lresence of Lresence of Lresence of Larararararge Wge Wge Wge Wge WoodyoodyoodyoodyoodyDebrisDebrisDebrisDebrisDebris

Definition and measurement of indicatorLarge woody debris (LWD) in the streamchannel is a good measure of both structuralstream habitat and the interaction of the streamwith its riparian zone. Large diameter wood incontact with the stream can be measured in thefield over several reaches within asubwatershed. The composite score isexpressed as the average number of LWDpieces encountered over a unit stream length.

Baseline condition compared to Ruralstream, with intact forested riparian zone,averaging five to 15 LWD pieces per 100 feetof stream reach (Fox et al., 2003).

References used to derive Most urbansubwatershed LWD data has been gathered forPacific Northwest streams with subwatershedIC ranging from 0 to 40% (May et al. 1997;Fox et al., 2003; Finkebine et al., 2000). Nosystematic data has been collected for NSstreams at the upper end of its IC range, andfor the entire UD category, although theCenter’s field assessments indicate that LWDis scarce or absent in these highly urbanstreams.

Utility in restoration planning and designLWD is helpful in assessing fishery resourcepotential, habitat quality, and the degree ofinteraction between the stream and riparianzone.

Comments More regional research is neededto assess LWD frequency for both the NS andUD stream categories.

11. Increased Summer Stream11. Increased Summer Stream11. Increased Summer Stream11. Increased Summer Stream11. Increased Summer StreamTTTTTemperaturesemperaturesemperaturesemperaturesemperatures

Definition and measurement of indicatorThis indicator is defined as the increase inaverage maximum summer stream temperaturecompared to a comparable rural streamdraining the same subwatershed area. Thewarming effect is often referred to as the delta-T and can be monitored using continuous orsimultaneous water temperature probes in thestream during the summer months.

Baseline condition compared to Averagesummer stream temperature for a rural streamthat has an intact riparian canopy to provideshade.

References used to derive The primary dataon the IC vs. stream temperature relationshipwas first proposed by Galli (1990). Therelationship is also indirectly supported by urbanheat island research conducted by Cheung(2002), who found a one degree F increase insummer surface air temperature for each 10%increment in local IC, when the presence ofadjacent water and forest cover was controlled.Confounding factors include effect of coldwater springs (Kilham and Steffy, 2002),stream canopy, and the presence of storm waterponds in a subwatershed. Still, there is a strongphysical basis for the IC/stream temperaturerelationship up to about 60% subwatershed IC.No stream temperature data could be found forUD subwatersheds, whose extensive below-ground drainage could potentially have acooling effect on summer stream temperatures.

Utility in restoration planning and designStream temperature is an important indicator todetermine fishery resource potential (e.g.,ability to support trout, salmon or sensitiveaquatic insect species).

Comments More research is needed to refinestream temperature predictions for the NS andUD stream categories.

E: Derivation of Urban WE: Derivation of Urban WE: Derivation of Urban WE: Derivation of Urban WE: Derivation of Urban WaterateraterateraterQuality PQuality PQuality PQuality PQuality Predictions for the ICMredictions for the ICMredictions for the ICMredictions for the ICMredictions for the ICM

12. Annual Nutrient L12. Annual Nutrient L12. Annual Nutrient L12. Annual Nutrient L12. Annual Nutrient Loadoadoadoadoad

Definition and computation of indicator Thisindicator is defined as the annual unit areamass storm water loading of phosphorus and/ornitrogen produced by an urban subwatershedcompared to a rural one. Nutrient loads can becomputed for any urban subwatershed usingthe Simple Method (Schueler, 1987), given areliable estimate of subwatershed IC andmedian event mean concentrations for therange of land uses present (Table A-1).



Table A-1: National Summary of Pollutant Concentrations in Storm Water Runoff

All Data Residential Commercial Industrial Freeway

# of storms sampled 3756 1069 497 524 185

Median Event Mean Concentrations EMC (mg/l or ppm)

Suspended Solids 58 48 43 77 99

Dissolved Solids 80 71 77 92 78

BOD5 8.6 9.0 11.9 9 8

COD 53 55 63 60 100

Fecal coliforms # 5081 7750 4500 2500 1700

Fecal streptococci # 17,000 24,000 10,800 13,000 17,000

Nitrate-N 0.6 0.6 0.6 0.7 0.28

TKN 1.4 1.4 1.6 1.4 2.0

Total Nitrogen 2.00 2.00 2.2 2.1 2.3

Total Phosphorus 0.27 0.3 0.22 .26 0.25

Dissolved P 0.12 0.17 0.11 0.11 0.20

Oil and Grease 4 3.1 4.7 4 8

Median Event Mean Concentrations EMC (ug/l or ppb)

Total Cadmium* 1.0 0.5 0.9 2.0 1.0

Total Chromium 7.0 4.6 6.0 15 8.3

Total Copper 16 11.1 17 22 35

Total Cyanide* 5.0 5.0 0.1 5.9 nd

Total Lead 16 11.1 18 25 25

Total Mercury* 0.2 0.2 0.2 0.1 0.2

Total Nickel * 8 5.4 7 16 9

Total Zinc 116 73 150 210 200

Fluoranthrene * 6 3 6 3.8 nd

Phenanthrene * 3.95 1.7 4.1 9 nd

Pyrene * 5.2 2.2 5.0 7.2 nd Source: Pitt et al. 2003 Notes: Medians are of detected values. An asterisk indicates constituent was undetected in more than half of all storm events. A # indicates bacteria measured in counts per 100 ml.



Baseline condition compared to The annualload of phosphorus or nitrogen produced by arural subwatershed, which has been definedregionally in the National Water QualityAssessment by the USGS (2001). The term“rural” refers to a mix of forest, pastures andcrops; note that subwatersheds with extensiverow crop or livestock operations can producemuch higher nutrient loads.

References used to derive The generalrelationship between storm water nitrogenloading rates and subwatershed IC has beenproposed by Schueler and Caraco (2001). Asimilar relationship between storm waterphosphorus loading rates and subwatershed IChas been presented by Caraco and Brown(2001, Table 4) and Caraco (2001, Figure 1).The nutrient load indicator does not includeany nutrients from wastewater discharges(either permitted or illicit), which are oftenfound in NS and UD subwatersheds and couldpossibly increase annual nutrient loads.

Utility in restoration planning and designNutrient loads can be a useful indicator tomeasure progress toward nutrient reductionefforts in subwatersheds where downstreameutrophication is a management concern.Various modeling tools can be used to estimatethe effect of various restoration practices toreduce subwatershed nutrient loading rates.Manual 2 in this series describes how theWatershed Treatment Model can be used forthis purpose.

Comments Pitt et al. (2003) has publishedextensive summaries of storm water runoffmonitoring data that establish reliableestimates of nutrient event meanconcentrations over a wide range ofsubwatershed IC in many regions of thecountry. Therefore, our confidence in theaccuracy of urban nutrient load predictions isfairly high, although we are less confident inthe estimates of rural nutrient loads used as thebaseline condition.

13. Exceedance of Bacteria13. Exceedance of Bacteria13. Exceedance of Bacteria13. Exceedance of Bacteria13. Exceedance of BacteriaStandardsStandardsStandardsStandardsStandards

Definition and measurement of indicatorThis indicator is defined as the frequency thatbacteria standards for water contact recreationare exceeded during wet weather and/or dryweather flow events in urban subwatersheds, asmeasured either by fecal coliform or E. colibacteria. Bacteria levels are typically measuredduring stream sampling at trend or sentinelstations within an urban subwatershed.

Baseline condition compared to Watercontact bacteria standards are exceeded inrural streams no more than 10 to 20% of stormevents per year, and are rarely exceeded duringdry weather(USGS, 2001).

References used to derive The basicconceptual model for dry and wet weatherbacteria behavior for urban watersheds hasbeen advanced by Schueler (1999 - Figure 1),based on an extensive analysis of storm waterand dry weather monitoring data for urbansubwatersheds across the country. Other datasources include Mallin et al. (2000, 2001) andPitt et al. (2003).

Utility in restoration planning and designThe bacteria indicator can help target dischargeprevention and source control restorationpractices, and can be used to set realistic andachievable goals for water contact recreationduring dry and wet weather.

Comments Extensive runoff monitoring hasestablished reliable estimates of storm waterbacteria concentrations over a wide range of ICin many regions of the country (Pitt et al.,2003). Although bacteria levels are highlyvariable, we are reasonably confident in thebroad pattern.



14. Aquatic Life T14. Aquatic Life T14. Aquatic Life T14. Aquatic Life T14. Aquatic Life Toxicityoxicityoxicityoxicityoxicity

Definition and measurement of indicatorThis indicator is defined as the potential forambient metal, pesticide or chlorideconcentrations in storm water runoff to causemortality in exposed aquatic organisms in urbanstreams. The degree to which ambientconcentrations of storm water pollutants cancause either chronic or acute toxicity to aquaticlife are still widely debated (see review inCWP, 2003).

Baseline condition compared to Ambientmetal, chloride or pesticide levels measuredduring storms in a rural stream. In general,acute toxicity is rarely encountered duringstorms in rural streams, unless adjacentagricultural or orchard spraying is unusuallyhigh.

References used to derive Severalresearchers have reported either acute orchronic toxicity within individual urbansubwatersheds with known impervious cover(Crunkilton et al., 1996; Field and Pitt, 1990;Ellis, 1986; Ireland et al. 1996; Connor, 1995;Environment Canada, 2001). Systematictoxicity monitoring across the range of ICincluded in the ICM, however, has not beenperformed. Several researchers do report astrong urban land use effect (Rice, 1999 andCallender and Rice, 2000).

Utility in restoration planning and designThis indicator is important in defining prioritiesand specific pollutant reduction targets forhotspot source control, municipal practices,neighborhood stewardship, and storm waterretrofitting in the context of a subwatershedrestoration plan.

Comments While the urban land use effect isquite strong for this indicator, the actual impactthat toxins exert on urban stream life is alsoquite complex, and probably differs for eachclass of toxins. In particular, the risk of aquaticlife toxicity in NS and UD subwatersheds isproblematic for several reasons. First, sensitiveaquatic organisms may already be absent in NSand UD subwatersheds as a result of otherhydrological, physical, habitat and water

quality stressors. Second, evidence exists thatpesticides may actually be generated at higherrates in impacted subwatersheds compared toNS and UD subwatersheds, since they havemore pervious area where pesticides could bepotentially applied (Hopkins and Hippe, 1999).By contrast, NS and UD subwatersheds usuallycontain a greater density of storm waterhotspots that have a higher potential for leaks,spills or illegal discharges of toxic pollutants.We have therefore elected to use a morenarrative rather than quantitative prediction todescribe this indicator that looks at potentialrather than actual frequency of acute orchronic toxicity.

15. Contaminated Sediments/F15. Contaminated Sediments/F15. Contaminated Sediments/F15. Contaminated Sediments/F15. Contaminated Sediments/FishishishishishAdvisoriesAdvisoriesAdvisoriesAdvisoriesAdvisories

Definition and measurement of indicatorThis indicator can be defined in one of twoways. The first way is to measure the extent towhich sediments are enriched in metals,organo-chlorine pesticides and/or polycyclicaromatic hydrocarbons (PAH) compared toreference sediments from rural subwatersheds.The second way is to measure whether thesame compounds accumulate in fish tissue tolevels that prompt an advisory restricting fishconsumption.

Baseline condition compared to Bothindicators are measured in relation to bottomsediments or fish tissue collected from ruralsubwatersheds. Rural bottom sediments can becontaminated by mercury (which is awidespread national problem) and somepesticides (from agricultural and orchards), butthey lack the distinctive “metal/PAH/organo-chlorine pesticide” fingerprint that is sodiagnostic of urban bottom sediments.

References used to derive Abundant evidenceexists to show a strong urban land use effect onsediment contamination. This is evident inurban storm water runoff concentrations (Pitt etal., 2003), urban stream bed sediments (Rice,1999), urban lake and reservoir sediments (VanMetre et al. 2000 and Callender and Rice,2000) and urban estuarine sediments (Hollandet al. 2003 and Velinsky and Cummins, 1994).A strong urban land use effect was also



reported in patterns of sediment contaminationin a national survey of sediment quality (USEPA, 1997). The same basic sedimentcontamination fingerprint has also been widelyobserved in the bottom sediments of manystorm water ponds (Schueler, 1996).

Much less evidence is available to make thelink between subwatershed IC and pollutantaccumulation in fish tissues that prompt fishconsumption advisories. There does appear tobe a strong clustering of fish consumptionadvisories around highly urban subwatershedsfor non-mercury pollutants (EPA, 2003). Inaddition, the USGS (2001) reports extensiveevidence of metal and PAH accumulation infish tissues in urban streams, but they did notsystematically monitor them over the widerange of subwatershed IC encompassed by theICM.

Utility in restoration planning and designThis indicator is important to define prioritiesand specific pollutant reduction targets forhotspot source control, discharge prevention,municipal practices, neighborhood stewardship,and storm water retrofits in a subwatershedplan.

Comments While there is strong evidence forthe relation of urbanization and sedimentcontamination/fish advisories, we lacksystematic monitoring over the full range ofsubwatershed IC to make quantitativepredictions at this time. We have thereforeelected to use a narrative rather thanquantitative prediction for this indicator.

16. T16. T16. T16. T16. Trash and Debrisrash and Debrisrash and Debrisrash and Debrisrash and Debris

Definition and measurement of indicatorThis indicator is ideally defined as the unit arealoading rate of trash and debris, expressed indry weight measured for an urbansubwatershed. At this time, however, there isno universally accepted method to report trashand debris loadings. Researchers havevariously measured trash/debris using units ofgallons, tons, cubic feet, and number of trashbags filled. There also is no consistency inwhether reported loads represent dry mass, wetmass or only floatables. In addition, the actualtechniques to measure trash/debris loads are

quite different, with researchers using booms tocapture trash during runoff events, samplingcatch basins, measuring the total volumecollected by volunteers along a given length ofstream or shoreline, or weighing trash collectedby skimmer boats in a harbor.

Baseline condition compared to A ruralstream, with minor trash loading.

References used to derive Several debrischaracterization studies were consultedincluding CRWQCB (2001), OCW (2000), andSteinberg et al. (2002). None of these studiessampled small urban subwatersheds, nor didthey evaluate trash/debris loads over the rangeof subwatershed IC included in the ICM. Itshould be noted, however, that most trash anddebris problems and management efforts dooccur in highly urban and ultra-urbansubwatersheds (i.e., NS and UD streams).

Utility in restoration planning and designThis indicator is useful to target streamcleanups, and define residential and businesssource control practices in contributingsubwatersheds. Severe trash and debrisproblems may call for enhanced municipalpractices such as street sweeping, storm draincleanouts, storm drain stenciling, or illegaldumping controls.

Comments This is perhaps the most poorlyunderstood ICM indicator, due to uneven andinconsistent data quality to measure trash/debris, and the fact that trash loading rateshave not been systematically monitored insubwatersheds over the full range of the ICcovered by the ICM model. Virtually no trashloading monitoring has been performed withinimpacted subwatersheds, so this indicatorprediction is merely an educated guess.

17. Other Storm W17. Other Storm W17. Other Storm W17. Other Storm W17. Other Storm Water Pater Pater Pater Pater Pollutantsollutantsollutantsollutantsollutants

Definition and measurement of indicatorThis indicator is defined as the annual unit areamass load of a storm water pollutant producedby an urban subwatershed compared to a ruralsubwatershed. It can be computed for anysubwatershed using the Simple Method(Schueler, 1987), given a reliable estimate ofsubwatershed IC and median event mean



concentrations for the range of land usespresent (see Table A-1). Reliable data areavailable for various measures of organiccarbon (COD, BOD5), metals (Cu, Zn, Pb),and oil and grease.

Baseline condition compared to The annualunit area pollutant load produced by a ruralsubwatershed, which has been definedregionally in the National Water QualityAssessment by the USGS (2001). The term“rural” refers to a mix of forest, pastures andcrops; subwatersheds with extensiveagricultural or livestock operations canproduce higher loads of organic carbon andother pollutants.

References used to derive Schueler (1987)proposed the general relationship betweenstorm water pollutant loading rates andsubwatershed IC, which requires a goodestimate of the storm water event meanconcentration (EMC). Pitt et al. (2003) presentEMC data for a range of common land uses,which is shown in Table A-1.

Utility in restoration planning and designThis is a useful indicator to measure pollutantload reduction needed to meet subwatershed orwatershed water quality, such as the WatershedTreatment Model (see Manual 2).

Comments As noted earlier, Pitt et al. (2003)have established reasonably accurate stormevent mean concentration data for mostconventional pollutants for most regions of thecountry (with the possible exception of thenorthern tier of U.S.). It should be noted thatmuch fewer data are available to characterizePAH compounds and chlorides.

FFFFF: Derivation of Aquatic Diversity: Derivation of Aquatic Diversity: Derivation of Aquatic Diversity: Derivation of Aquatic Diversity: Derivation of Aquatic DiversityPPPPPredictions for the ICMredictions for the ICMredictions for the ICMredictions for the ICMredictions for the ICM

18. Aquatic Insect Diversity18. Aquatic Insect Diversity18. Aquatic Insect Diversity18. Aquatic Insect Diversity18. Aquatic Insect Diversity

Definition and measurement of indicatorThis index is defined as the averagesubwatershed macro-invertebrate or aquaticinsect diversity score, as computed by BenthicIndex of Biotic Integrity or B-IBI (Barbour etal., 1999). It is typically measured in multiple

stream reaches within a subwatershed.

Baseline condition compared to B-IBIscores for rural streams typically range from“good” to “very good.”

References used to derive Our predictionsare based on visual inspection of B-IBI vs. ICdata plots from the following studies Bowardet al. (1999); MNCPPC (2000); Horner et al.(1997); Black and Veatch (1994); Kennen(1999); Yoder (1991) and Fairfax County(2001). In general, B-IBI scores are onlyreported up to about 40 to 45% subwatershedIC, so the poor diversity predicted for streamsin the upper NS and the entire UD categorysimply represents an extension of the data trendline.

Utility in restoration planning and designThis indicator helps assess the generalbiological health of an urban stream, and can beused to track improvements in stream health asa result of the implementation of subwatershedrestoration practices.

Comments The relationship between IC anddeclining B-IBI scores is strongly supported bycurrent research, although aquatic insectdiversity data for UD streams is generallylacking.

19. EPT T19. EPT T19. EPT T19. EPT T19. EPT Taxaaxaaxaaxaaxa

Definition and measurement of indicatorThis indicator is defined as the proportion ofsensitive stonefly, caddisfly and mayfly speciesin the stream insect community, expressed asthe percent of the total score for a rural“reference” stream. Streams with high EPTscores contain many pollution and/ortemperature sensitive species, whereas streamswith low scores are deemed pollution tolerant.

Baseline condition compared to EPT scoresfor a rural stream, which are typically 80 to100% of the reference stream value.

References used to derive The primaryreferences used to predict this indicator wereMaxted and Shaver (1997) and Morse (2001),although this metric is also one of thecomponents of the B-IBI scoring (see # 18).



Utility in restoration planning and designThis measure of the pollution tolerance of theaquatic insect community indicates the degreeto which pollution, degraded habitat, or otherstressors are influencing local stream ecology.

Comments Again, very little research isavailable to characterize EPT scores forstreams with more than 40% subwatershed IC,which makes it somewhat hard to makepredictions for NS and UD stream categories.Based on extensions of the trend lines,however, it is doubtful that any highly urbanstreams contain any pollution or temperaturesensitive species.

20. F20. F20. F20. F20. Fish Diversityish Diversityish Diversityish Diversityish Diversity

Definition and measurement of indicatorThis indicator is defined as the average fishdiversity score for an urban subwatershedcompared to a rural one. The fish Index ofBiotic Integrity or F-IBI is usually sampled inmultiple stream reaches to obtain an averagescore for an urban subwatershed (Barbour etal., 1999).

Baseline condition compared to Ruralstreams typically have “good” to “very good”fish-IBI scores, unless there has been a majorchange in land use or riparian management inthe subwatershed (Harding et al., 1998).

References used to derive These predictionsare based on visual inspection of F-IBI vs. ICdata plots from the following studies Wang etal. (2001); MNCPPC (2000); MWCOG(1992); Meyer and Couch (2000); Boward etal. (1999); Horner et al. (2001) and Couch etal. (1997). As with B-IBI scores, reported F-IBI data extend only from five to about 45%subwatershed IC, so the poor diversitypredicted for streams in the upper NS and theentire UD category simply represents anextension of the data trend line.

Utility in restoration planning and designFish diversity scores are an excellent indicatorof stream health, from the perspective of bothstream researchers and the general public, andscores can be tracked over time to measureprogress toward fishery restoration goals.

21. T21. T21. T21. T21. Trout or Salmonrout or Salmonrout or Salmonrout or Salmonrout or Salmon

Definition and measurement of indicatorThis indicator is defined as the ability tomaintain a self-reproducing population of troutor salmon within a subwatershed. Where this isnot possible, the indicator is alternativelydefined as the ability to maintain a put-and-takefishery in the stream. This indicator is easilymeasured through fishery and spawningsurveys in an urban subwatershed.

Baseline condition compared to A ruralstream with habitat conditions that can supporttrout or salmon populations.

References used to derive A number ofresearchers have examined the effect of IC ontrout and salmon and have found that thesepopulations are often absent or extremelystressed above 10% subwatershed IC (Bowardet al., 1999; Horner et al., 1999; May et al.,1997; WDFW, 1997; Kilham and Steffy, 2002;Scott et al., 1986; Kemp and Spotila, 1997;Moscript and Montgomery, 1997). It may bepossible to support salmon at the lower ICrange of impacted subwatersheds, but norecords of self-reproducing populations couldbe found in either NS or UD subwatersheds.Urban fishery biologists have established put-and-take recreational trout fisheries in somelarger I and NS streams. In addition, there issome data that hardier cutthroat trout mayinhabit I and NS streams for at least part oftheir life cycles (May et al., 1997).

Utility in restoration planning and designThis indicator helps set expectations for thefishery resource potential of an urbansubwatershed. If a stream can potentiallysupport a self-reproducing or put-and-takefishery, it greatly affects the selection of whichsubwatershed restoration practices to apply(e.g., stream repair/restoration techniques,elimination of fish barriers, improved riparianmanagement).

Comments This indicator obviously only appliesto eco-regions that can support a cold-waterfishery. An alternative “indicator” fish speciescould be selected for regions that have a warm-water fishery.



22. Riparian Plant Diversity22. Riparian Plant Diversity22. Riparian Plant Diversity22. Riparian Plant Diversity22. Riparian Plant Diversity

Definition and measurement of indicatorThis indicator measures plant diversity andcommunity structure in the remaining floodplain forests and wetland fragments of thestream corridor. The three main elements usedto describe this indicator are a) the relativedominance of exotic and native plant specieswithin the fragment, b) fragment patch size andstructure and c) overall plant diversity withinthe fragment compared to a rural streamcorridor. Each of these elements can bemeasured along the stream corridor, but theyrarely are.

Baseline condition compared to Each of thethree riparian elements should be comparedagainst values obtained from flood plain forestor wetland reference sites located in the ruralstream corridor.

References used to derive This narrativeprediction is based on research that has showna strong urban land use effect for each elementin urban riparian areas (Brush and Zipperer,2002; Groffman et al. 2003; Findlay andHoulihan, 1997; Taylor et al., 1995), as well asextensive anecdotal evidence from urbanstream corridor surveys. Consistent anduniform techniques to measure and compareriparian plant diversity, however, have notsystematically been applied over the range ofsubwatershed IC encompassed by the ICM.

Utility in restoration planning and designThis indicator could be quite useful in definingthe prospects for effective riparian and naturalarea restoration in the urban stream corridor,but is not fully developed at this time.

Comments This indicator is expressed as verygeneral narrative criteria, relating to dominanceof exotic plants, average fragment size andstructure and overall plant diversity within thefragment.

G: SummarG: SummarG: SummarG: SummarG: Summaryyyyy

The ICM organizes a combination of publishedand unpublished research, engineering models,field experience, and hypotheses into a streamclassification system for three kinds of urbansubwatersheds. The strongest evidence for ICMpredictions tends to be concentrated in the 10 to40% subwatershed IC range; much less isknown about the behavior of streams in theupper end of the NS category and the entire UDcategory. We strongly believe additionalresearch on NS and UD streams will furtherrefine and tighten ICM predictions, and inviteresearchers to test these hypotheses in futuremonitoring.

Tables A-2, A-3, and A-4 provide a summary ofthe ICM predictions for impacted, non-supporting and urban drainage streamclassifications, respectively. These tables alsoinclude a confidence factor, or CF for eachindicator, which qualitatively expresses therelative confidence in each indicator predictionon a scale of one to five (with five being themost confident and one being least confident).



Table A-2: ICM Predictions for Impacted Streams (11 to 25% IC) Stream Indicator Prediction CF

Influence of Storm Water Runoff 10 to 30% of rainfall converted to runoff 5

Flood Plain Expansion Index Peak discharge for 100-yr storm increased by a factor of 1.1 to 1.5

4

Bankfull Flooding Frequency 1.5 to 3 bankfull flood events occur per year 4 Stream Enclosure/Modification 60 to 90% of stream network intact 3 Riparian Forest Continuity 50 to 70% of riparian forest buffer intact 3 Stream Interruption 1 to 2 crossings per stream mile 2 Channel Enlargement Cross-sectional area enlarges by a factor of 1.5 to 2.5 3 Sediment Supply to Stream 2 to 5x more annual yield during enlargement phase 3 Typical Stream Habitat Score Fair, but variable 3 Presence of Large Woody Debris 2 to 8 pieces per 100 feet of stream 2 Summer Stream Temperature 2 to 4 degrees F warmer 3 Annual Nutrient Load 1 to 2 times higher than rural background 4 Violations of Bacteria Standards Frequent violations during wet weather 4 Potential Aquatic Life Toxicity Acute toxicity rare, chronic possible 2

Contaminated Bottom Sediments Sediments enriched, but not contaminated; fish advisories uncommon

2

Trash and Debris Load 1 to 2 tons per square mile per year 2 Aquatic Insect Diversity Fair to good B-IBI scores 4 EPT Taxa 40 to 70% of reference 4 Fish Diversity Fair to good F-IBI scores 4 Capacity to Support Trout or Salmon Some limited potential 4 Riparian Plant Diversity Stressed and simplified plant communities 2 CF: Confidence factor based on scale of 1 to 5, with 5 representing the highest level of confidence.

Table A-3: ICM Predictions for Non-Supporting Streams (26 to 59% IC) Stream Indicator Prediction CF


Flood plain Expansion Peak Discharge for 100-year storm increased by a factor of 1.5 to 2 4

Bankfull Flood Frequency 3 to 7 bankfull flood events occur per year 4 Stream Enclosure/Modification 25 to 60% of stream network intact 3 Riparian Forest Continuity 30 to 60% of riparian forest buffer intact 3 Stream Interruption 2 to 10 stream crossings per mile 2 Channel Enlargement Cross-sectional area enlarges by a factor of 2.5 to 6 3 Sediment Supply to Stream 5 to 10x more sediment yield during enlargement phase 2 Typical Stream Habitat Score Consistently fair to poor 3 Presence of Large Woody Debris Scarce or absent 2 Summer Stream Temperatures 4 to 8 degrees F warmer 3 Annual Nutrient Load 2 to 4 times higher than rural background 4

Violations of Bacteria Standards Continuous violations during wet weather; episodic violations during dry weather 4

Potential Aquatic Life Toxicity Moderate potential for acute toxicity during some storms and spills 3

Contamination of Bottom Sediments Episodic potential for acute toxicity; fish advisories likely 3 Trash and Debris Loading 2 to 5 tons per square mile per year 2 Aquatic Insect Diversity Poor B-IBI scores 4 EPT Taxa 20 to 50 of natural reference 3 Fish Diversity Poor F-IBI scores 4 Capacity to Support Trout or Salmon Temporary use only (i.e., put-and-take) 3 Riparian Plant Diversity Simplified and dominated by invasive species 2 CF: Confidence factor based on scale of 1 to 5, with 5 representing the highest level of confidence.



Table A-4: ICM Predictions for Urban Drainage Streams ( >60% IC) Stream Indicator Prediction CF


Flood Plain Expansion Index Peak Discharge for 100-year storm increased by factor of 2 to 3 4

Bankfull Flooding Frequency 7 to 10 bankfull events per year 2 Stream Enclosure/Modification 10 to 30% of stream network intact 2 Riparian Forest Continuity >30% of riparian forest buffer intact 2 Stream Interruption No streams left to cross 1 Channel Enlargement Cross-sectional area enlarges by a factor of 6 to 12 2 Sediment Supply to Stream Sediment supply may decline after enlargement 1 Typical Stream Habitat Score Poor, often absent 2 Presence of Large Woody Debris Absent 2 Summer Stream Temperatures More than 8 degrees F warmer 3 Annual Nutrient Load 4 to 6 times higher than rural background 4

Violations of Bacteria Standards Continuous violations during wet weather, frequent violations during dry weather 4

Potential Aquatic Life Toxicity High potential for acute toxicity episodes during dry and wet weather 2

Contaminated Bottom Sediments Sediment contamination and bio-accumulation should be presumed 3

Trash and Debris Loads 5 to 10 tons per square mile 2 Aquatic Insect Diversity Very poor B-IBI scores 1 EPT Taxa 0 to 20% of reference 2 Fish Diversity Very poor F-IBI scores 2 Capacity to Support Trout or Salmon None 2 Riparian Plant Diversity Isolated remnants; Dominated by invasive species 2 CF: Confidence factor based on scale of 1 to 5, with 5 representing the highest level of confidence.

Urban Subwatershed Restoration Manual 1 B-1

Appendix B: Organization of Restoration Technique Profile Sheets

Appendix B: Organization of RAppendix B: Organization of RAppendix B: Organization of RAppendix B: Organization of RAppendix B: Organization of RestorationestorationestorationestorationestorationTTTTTechnique Pechnique Pechnique Pechnique Pechnique Profile Sheets for the Manual Seriesrofile Sheets for the Manual Seriesrofile Sheets for the Manual Seriesrofile Sheets for the Manual Seriesrofile Sheets for the Manual Series

Manual 3: Storm WManual 3: Storm WManual 3: Storm WManual 3: Storm WManual 3: Storm Water Rater Rater Rater Rater RetrofitetrofitetrofitetrofitetrofitPPPPPracticesracticesracticesracticesractices

Storage RStorage RStorage RStorage RStorage Retrofit Tetrofit Tetrofit Tetrofit Tetrofit TechniquesechniquesechniquesechniquesechniquesModify Existing Ponds (SR-1)Storage Above Roadway Culverts (SR-2)New Storage Below Outfalls (SR-3)Storage in the Conveyance System (SR-4)Storage in Road Right of Ways (SR-5)Storage Near Parking Lots (SR-6)

On-site Non-On-site Non-On-site Non-On-site Non-On-site Non-RRRRResidential Residential Residential Residential Residential RetrofitetrofitetrofitetrofitetrofitTTTTTechniquesechniquesechniquesechniquesechniquesBioretention (OS-7)Swales (OS-8)Infiltration Trench (OS-9)Storm water Filters (OS-10)Permeable Pavement (OS-11)Storm Water Planters (OS-12)Cisterns (OS-13)Green Rooftops (OS-14)

On-site ROn-site ROn-site ROn-site ROn-site Residential Residential Residential Residential Residential RetrofitetrofitetrofitetrofitetrofitTTTTTechniquesechniquesechniquesechniquesechniquesRain Barrels (OS-15)Rain Gardens (OS-16)French Drains and Dry Wells (OS-17)

Manual 4: Manual 4: Manual 4: Manual 4: Manual 4: Stream RepairStream RepairStream RepairStream RepairStream RepairPPPPPracticesracticesracticesracticesractices

Stream Cleanup TStream Cleanup TStream Cleanup TStream Cleanup TStream Cleanup TechniquesechniquesechniquesechniquesechniquesStream Cleanups (C-1)Stream Adoption (C-2)

Stream RStream RStream RStream RStream Repair Tepair Tepair Tepair Tepair TechniquesechniquesechniquesechniquesechniquesBoulder Revetment (R-3)Rootwad Revetment (R-4)Imbricated Rip Rap (R-5)A-Jacks (R-6)Live Cribwalls (R-7)Streambank Shaping (R-8)Coir Fiber Logs (R-9)Erosion Control Fabrics (R-10)Soil Lifts (R-11)Live Stakes (R-12)Live Fascines (R-13)Brush Mattress (R-14)Vegetation Establishment (R-15)Wing Deflectors (R-16)Log, Rock and J Vanes (R-17)Rock Vortex Weir (R-18)Rock Cross Vane (R-19)Step Pools (R-20)V Log Drops (R-21)Lunkers (R-22)Large Woody Debris (R-23)Boulder Clusters (R-24)Baseflow Channel Creation (R-25)Parallel Pipes (R-26)Stream Daylighting (R-27)Culvert Modification (R-28)Culvert Replacement and Removal (R-29)Devices to Pass Fish (R-30)

Comprehensive RComprehensive RComprehensive RComprehensive RComprehensive RestorationestorationestorationestorationestorationTTTTTechniquesechniquesechniquesechniquesechniquesCombining Stream Repair Practices (CR-31)Channel Redesign (CR-32)De-channelization (CR-33)

Urban Subwatershed Restoration Manual 1B-2


Manual 5: Manual 5: Manual 5: Manual 5: Manual 5: RiparianRiparianRiparianRiparianRiparianManagement PManagement PManagement PManagement PManagement Practicesracticesracticesracticesractices

Site PSite PSite PSite PSite Preparation Treparation Treparation Treparation Treparation TechniquesechniquesechniquesechniquesechniquesRemoval/Prevention of Dumping (SP-1)Invasive Species Control (SP-2)Urban Soil Preparation (SP-3)Storm Water Management (SP-4)

RRRRRevegetation Tevegetation Tevegetation Tevegetation Tevegetation TechniquesechniquesechniquesechniquesechniquesActive Reforestation (F-5)Park/Greenway Plantings (F-6)Natural Regeneration (F-7)Riparian Wetland Restoration (F-8)

Manual 6: Manual 6: Manual 6: Manual 6: Manual 6: Discharge PDischarge PDischarge PDischarge PDischarge PreventionreventionreventionreventionreventionPPPPPracticesracticesracticesracticesractices

TTTTTechniques to Fechniques to Fechniques to Fechniques to Fechniques to Find Discharind Discharind Discharind Discharind DischargesgesgesgesgesOutfall Reconnaissance InvestigationChemical Outfall MonitoringIn-stream Dry Weather SamplingIn-Pipe InvestigationsHotlines and Citizen ReportingDye, Smoke and TV Testing of Suspect PipesInfrared Aerial ThermographyFinding Failing Septic SystemsMunicipal Spill ManagementStructural RepairsPublic Education/Employee TrainingAuthority to Control Discharges

Manual 7: WManual 7: WManual 7: WManual 7: WManual 7: WatershedatershedatershedatershedatershedFFFFForestrorestrorestrorestrorestryyyyy P P P P Practicesracticesracticesracticesractices

Site PSite PSite PSite PSite Preparation Treparation Treparation Treparation Treparation TechniquesechniquesechniquesechniquesechniquesRemoval/Prevention of Dumping (SP-1)Invasive Species Control (SP-2)Urban Soil Preparation (SP-3)Storm Water Management (SP-4)

RRRRRe-vegetation Te-vegetation Te-vegetation Te-vegetation Te-vegetation TechniquesechniquesechniquesechniquesechniquesActive Reforestation (F-5)Park/Greenway Plantings (F-6)Natural Regeneration (F-7)Riparian Wetland Restoration (F-8)

Manual 8: Manual 8: Manual 8: Manual 8: Manual 8: PPPPPollution Sourceollution Sourceollution Sourceollution Sourceollution SourceControl PControl PControl PControl PControl Practicesracticesracticesracticesractices

Neighborhood StewardshipNeighborhood StewardshipNeighborhood StewardshipNeighborhood StewardshipNeighborhood StewardshipTTTTTechniquesechniquesechniquesechniquesechniquesReduce Fertilizer Use (N-1)Reduced Pesticide Use (N-2)Xeriscaping (N-3)Natural Landscaping (N-4)Tree Planting (N-5)Yard Waste Composting (N-6)Soil Reclamation (N-7)Erosion Repair (N-8)Septic System Maintenance (N-9)Safe Pool Discharges (N-10)Safe Car Washing (N-11)Driveway Sweeping (N-12)Safe Deicer Use (N-13)Household Hazardous Waste Collection (N-14)Car Fluid Recycling (N-15)Downspout Disconnection (N-16)Single Lot Controls (N-17)Pet Waste Pick-up (N-18)Storm Water Practice Maintenance (N-19)Bufferscaping (N-20)Storm Drain Marking (N-21)

Hotspot PHotspot PHotspot PHotspot PHotspot Pollution Pollution Pollution Pollution Pollution PreventionreventionreventionreventionreventionTTTTTechniquesechniquesechniquesechniquesechniquesVehicle Maintenance and Repair (H-1)Vehicle Fueling (H-2)Vehicle Washing (H-3)Vehicle Storage (H-4)Loading and Unloading (H-5)Outdoor Storage (H-6)Spill Prevention and Response (H-7)Dumpster Management (H-8)Building Repair and Remodeling (H-9)Building Maintenance (H-10)Parking Lot Maintenance (H-11)Turf Management (H-12)Landscaping/Grounds Care (H-13)Swimming Pool Discharges (H-14)Unique Hotspot Operations (H-15)

Urban Subwatershed Restoration Manual 1 B-3


Manual 9: Manual 9: Manual 9: Manual 9: Manual 9: MunicipalMunicipalMunicipalMunicipalMunicipalPractices and ProgramsPractices and ProgramsPractices and ProgramsPractices and ProgramsPractices and Programs

TTTTTechniques for Streets and Stormechniques for Streets and Stormechniques for Streets and Stormechniques for Streets and Stormechniques for Streets and StormDrainsDrainsDrainsDrainsDrainsStreet and Parking Lot SweepingCatch Basin CleaningRoad MaintenanceEmployee Training

Best PBest PBest PBest PBest Practices for New Constructionractices for New Constructionractices for New Constructionractices for New Constructionractices for New ConstructionConduct Site ESAProtect and Restore Natural AreaNatural Area MaintenanceEfficient Use of ICEmploy BSDMaximize Transportation ChoicesManage Rooftop RunoffCourtyard Plaza DesignMinimize Parking Lot RunoffDesign StreetscapesMunicipal Pollution Prevention

Inspection and EnforcementInspection and EnforcementInspection and EnforcementInspection and EnforcementInspection and EnforcementEnforcement

Urban Subwatershed Restoration Manual 1B-4


Urban Subwatershed Restoration Manual 1 R-1

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Urban Subwatershed Restoration Manual 1R-2

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Holland, A., D. Sanger, C. Gawle, S. Lerberg,M. Santiago, G. Riekerk, L. Zimmermanand G. Scott. 2003. “Linkages BetweenTidal Creek Ecosystem and the Landscapeand Demographic Attributes of TheirWatersheds.” Journal of ExperimentalMarine Biology and Ecology. 4243:

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Documents

MANUAL 1 COVER · Photo Acknowledgments page 7 USDA NRCS page 19 page 33 Fairfax County, VA page 38 USDA NRCS page 38 Eric Livingston page 39 Roger Bannerman page 39