Sediment TMDL Development Report for Benthic Impairments ...€¦ · Quality Assessment 305(b)/303(d) Integrated Report (VADEQ, 2008). The Virginia Department of Environmental Quality

Sediment TMDL Development Report for Benthic Impairments in Long Branch and Buffalo River Amherst County, Virginia

Submitted by:

Virginia Department of Environmental Quality

Prepared by:

Virginia Tech Department of Biological Systems Engineering

July 2, 2013

VT-BSE Document No. 2013-0006

i

Project Personnel

Virginia Tech, Department of Biological Systems Engineering (BSE) Karen Kline, Research Scientist Gene Yagow, Sr. Research Scientist Brian Benham, Associate Professor and Extension Specialist

Virginia Department of Environmental Quality (DEQ) Paula Nash, Blue Ridge Region TMDL Coordinator Sandra Mueller, Central Office

Nesha McRae, TMDL/Watershed Field Coordinator, Harrisonburg

For additional information, please contact: Virginia Department of Environmental Quality

Water Quality Assessment Office, Richmond: Sandra Mueller (804) 698-4324 Blue Ridge Region Office, Roanoke: Paula Nash, (434) 582-6216

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Table of Contents EXECUTIVE SUMMARY .............................................................................. ES-1

Introduction ................................................................................................. ES-1 Applicable Water Quality Standard and Designated Use ......................... ES-3

Benthic Stressor Analysis ............................................................................ ES-3 Sediment Modeling Approach ..................................................................... ES-4 Accounting for Critical Conditions and Seasonal Variations ........................ ES-4 Simulated Sediment Loads ......................................................................... ES-5 The Sediment TMDLs for Long Branch and Buffalo River ........................... ES-6 Allocation Scenarios .................................................................................... ES-8 Reasonable Assurance for Implementation ................................................. ES-9

CHAPTER 1: INTRODUCTION ......................................................................... 1 1.1. Background ................................................................................................ 1

1.1.1. TMDL Definition and Regulatory Information ....................................... 1 1.1.2. Impairment Listing................................................................................ 1 1.1.3. Pollutants of Concern ........................................................................... 3

1.2. Designated Uses and Applicable Water Quality Standards ........................ 3 1.2.1. Designation of Uses (9 VAC 25-260-10) .............................................. 3 1.2.2. General Standard (9 VAC 25-260-20) .................................................. 3

CHAPTER 2: WATERSHED CHARACTERIZATION ......................................... 6 2.1. Water Resources ........................................................................................ 6 2.2. Eco-region .................................................................................................. 6 2.3. Soils and Geology ...................................................................................... 7 2.4. Climate ....................................................................................................... 7 2.5. Land Use .................................................................................................... 8 2.6. Biological Monitoring Data – Benthic Macro-invertebrates ........................ 10 2.7. Biological Monitoring Data – Habitat ......................................................... 17 2.8. Water Quality Data ................................................................................... 18

2.8.1. DEQ Ambient Monitoring Data ........................................................... 18 2.8.2. DEQ Stream Tests for Metals and Organic Compounds .................... 19 2.8.3. DEQ – Other Relevant Monitoring or Reports ..................................... 20

2.8.3.1 Relative Bed Stability (RBS) Analysis .......................................... 20 2.8.4. Permitted Point Sources .................................................................... 20

CHAPTER 3: BENTHIC STRESSOR ANALYSIS .............................................. 21 3.1. Introduction ............................................................................................... 21 3.2. Stressor Analyses Summaries ................................................................. 21

CHAPTER 4: SETTING REFERENCE TMDL LOADS ...................................... 23 4.1. TMDL Reference Watershed Selection .................................................... 23 4.2. TMDL Modeling Target Loads .................................................................. 25

CHAPTER 5: MODELING PROCESS FOR DEVELOPMENT OF THE TMDL ... 27 5.1. Model Selection ........................................................................................ 27 5.2. GWLF Model Development for Sediment ................................................. 29 5.3. Input Data Requirements .......................................................................... 30

5.3.1. Climate Data ...................................................................................... 30 5.3.2. Existing Land Use .............................................................................. 30

5.4. Future Land Use ....................................................................................... 32 5.5. GWLF Parameter Evaluation .................................................................... 33

5.5.1. Hydrology Parameters ....................................................................... 34

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5.5.2. Sediment Parameters ........................................................................ 35 5.6. Supplemental Post-Model Processing ...................................................... 35 5.7. Representation of Sediment Sources ....................................................... 36

5.7.1. Surface Runoff ................................................................................... 37 5.7.2. Channel and Streambank Erosion ..................................................... 37 5.7.3. Industrial Stormwater ......................................................................... 38 5.7.4. Construction Stormwater ................................................................... 38 5.7.5. Other Permitted Sources (VPDES and General Permits) .................. 38

5.8. Accounting for Critical Conditions and Seasonal Variations ..................... 38 5.8.1. Selection of Representative Modeling Period .................................... 38 5.8.2. Critical Conditions .............................................................................. 39 5.8.3. Seasonal Variability ........................................................................... 39

5.9. Existing and Future Sediment Loads ........................................................ 39 CHAPTER 6: TMDLS AND ALLOCATIONS ..................................................... 41

6.1. Long Branch and Buffalo River Sediment TMDLs .................................... 41 6.1.1. TMDL Components ............................................................................ 41

6.1.1.1. Waste Load Allocation ................................................................. 41 6.1.1.2. Margin of Safety .......................................................................... 42 6.1.1.3. Load Allocation ............................................................................ 42

6.1.2. Maximum Daily Loads ........................................................................ 43 6.2. Allocation Scenarios ................................................................................. 44

CHAPTER 7: TMDL IMPLEMENTATION ......................................................... 47 7.1. Link to ongoing Restoration Efforts ........................................................... 48 7.2. Reasonable Assurance for Implementation .............................................. 48

7.2.1. TMDL Monitoring ............................................................................... 48 7.2.2. Regulatory Framework ....................................................................... 48

7.2.2.1 Federal Regulations ..................................................................... 48 7.2.2.2 State Regulations ......................................................................... 48

7.2.3. Implementation Funding Sources ...................................................... 49 7.2.4. Reasonable Assurance Summary ...................................................... 49

CHAPTER 8: PUBLIC PARTICIPATION ........................................................... 51 CHAPTER 9: REFERENCES ........................................................................... 52 APPENDIX A: GLOSSARY OF TERMS ........................................................... 54 APPENDIX B: GWLF MODEL PARAMETERS ................................................. 56

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List of Tables

Table ES-1. Existing and Future Sediment Loads ........................................................ ES-6 Table ES-2. The Long Branch and Buffalo River Sediment TMDLs .......................... ES-7 Table ES-3. Long Branch and Buffalo River Maximum “Daily” Sediment Loads ...... ES-7 Table ES-4. Sediment TMDL Load Allocation Scenarios, Long Branch .................... ES-8 Table ES-5. Sediment TMDL Load Allocation Scenarios, Buffalo River ................... ES-9 Table 2-1. NASS Land Use Summary in Buffalo River Watersheds (acres) ..................... 9 Table 2-2. Taxa Inventory by Sample Date in Long Branch (LOB) ................................ 12 Table 2-3. Biological Index (VSCI) Scores for Long Branch (LOB) ............................... 13 Table 2-4. Taxa Inventory by Sample Date in Buffalo River (BUF) ............................... 15 Table 2-5. Biological Index (VSCI) Scores for Buffalo River (BUF) .............................. 16 Table 2-6. Habitat Metric Scores for Long Branch (LOB) ............................................... 17 Table 2-7. Habitat Metric Scores for Buffalo River (BUF) .............................................. 18 Table 2-8. Nutrient Concentration Averages and Ratios .................................................. 19 Table 2-9. DEQ Channel Bottom Sediment Monitoring and Screening Criteria for Metals

................................................................................................................................... 19 Table 2-10. Permitted Discharges ..................................................................................... 20 Table 4-1. Comparison of Potential Reference Watershed Characteristics to Long Branch

Watershed ................................................................................................................. 25 Table 4-2. Comparison of Potential Reference Watershed Characteristics to Buffalo River

Watershed ................................................................................................................. 25 Table 5-1. NASS Land Use Group Distributions ............................................................. 30 Table 5-2. Modeled Land Use Categories ........................................................................ 32 Table 5-3. Existing Land Use Distributions ..................................................................... 33 Table 5-4. Industrial Stormwater General Permit (ISWGP) WLA Loads ........................ 38 Table 5-5. Future Sediment Loads in the TMDL Watersheds and Existing Sediment

Loads in the Reference Watershed ........................................................................... 40 Table 6-1. Aggregated Construction WLA Loads ............................................................ 42 Table 6-2. Long Branch and Buffalo River Sediment TMDLs ........................................ 43 Table 6-3. Long Branch and Buffalo River Maximum “Daily” Sediment Loads ............ 44 Table 6-4. Sediment TMDL Load Allocation Scenario, Long Branch ............................. 45 Table 6-5. Sediment TMDL Load Allocation Scenario, Buffalo River ........................... 46 Table B-1. GWLF Watershed Parameters ........................................................................ 57 Table B-2. GWLF Monthly ET Cover Coefficients ......................................................... 57 Table B-3. GWLF Land Use Parameters .......................................................................... 57

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List of Figures

Figure ES-1. Location of Impaired Segments and TMDL Watersheds ........................ ES-2 Figure 1-1. Location of Impaired Segments and TMDL Watersheds ................................ 2 Figure 2-1. NASS Generalized Land Use in the Buffalo River Watershed ........................ 8 Figure 2-2. Location of DEQ Monitoring Stations in the Buffalo River Watershed ........ 10 Figure 2-3. VSCI Scores for Long Branch (LOB) ............................................................ 13 Figure 2-4. VSCI Scores for Buffalo River (BUF) ........................................................... 16 Figure 4-1. Location of Long Branch, Buffalo River and Potential Reference Watersheds

................................................................................................................................... 24 Figure 5-1. Buffalo River sub-watersheds and impaired segments .................................. 29

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List of Acronyms

BMP Best Management Practices BSE Biological Systems Engineering CBWM Chesapeake Bay Watershed Model COD Chemical Oxygen Demand CV Coefficient of variation DCR Virginia Department of Conservation and Recreation DEQ Virginia Department of Environmental Quality DO Dissolved Oxygen E&S Erosion and Sediment Control Program (DCR) EDAS Environmental Data Analysis System GIS Geographic Information Systems LA Load Allocation LRBS Log Relative Bed Stability MDL Minimum Detection Limit, also Maximum Daily Load MFBI Modified Family Biotic Index MOS Margin of Safety MS4 Municipal Separate Storm Sewer System program (EPA) NASS National Agricultural Statistics Service (USDA) NPS Non-Point Source NRCS Natural Resources Conservation Service (USDA) PEC Probable Effect Concentrations RBP Rapid Bioassessment Protocol TKN Total Kjeldahl Nitrogen TMDL Total Maximum Daily Load TN Total Nitrogen TP Total Phosphorous TSS Total Suspended Solids USDA United States Department of Agriculture USEPA United States Environmental Protection Agency VSCI Virginia Stream Condition Index VPDES Virginia Pollutant Discharge Elimination System VSMP Virginia Stormwater Management Program VT Virginia Tech WIP Watershed Implementation Plan WLA Waste Load Allocation WQC Water Quality Criteria

ES-1

EXECUTIVE SUMMARY

Introduction

Section 303(d) of the Federal Clean Water Act and the U.S. Environmental

Protection Agency’s (USEPA) Water Quality Planning and Management

Regulations (40 CFR Part 130) require states to identify water bodies that violate

state water quality standards and to develop a Total Maximum Daily Load

(TMDLs) for such water bodies. A TMDL reflects the pollutant load a water body

can receive and still meet water quality standards. TMDLs are pollutant-specific.

A TMDL establishes the allowable pollutant loading from both point and nonpoint

sources for a water body, allocates the load among the pollutant contributors, and

provides a framework for taking actions to restore water quality.

The subjects of this TMDL study area two impaired stream segments in

the Buffalo River watershed: one on Buffalo River and one on Long Branch,

which is a tributary to Buffalo River. These impaired segments are located within

the James River Basin within Amherst County in the Commonwealth of Virginia,

Figure ES-1. The watersheds delineated to simulate sediment loading to these

impaired segments are also shown in the figure and will herein be referred to as

the TMDL watersheds.

Long Branch was originally listed as impaired due to water quality

violations of the general aquatic life (benthic) standard in the 2008 Virginia Water

Quality Assessment 305(b)/303(d) Integrated Report (VADEQ, 2008). The

Virginia Department of Environmental Quality (DEQ) has identified this

impairment as Cause Group Code H11R-01-BEN, and delineated the benthic

impairment as 3.40 miles on Long Branch (stream segment VAC-

H11R_LOB01A04). The Long Branch impaired segment runs from the

headwaters downstream to its confluence with Buffalo River.

ES-2

Figure ES-1. Location of Impaired Segments and TMDL Watersheds

The DEQ 2010 Fact Sheets for Category 5 Waters (VADEQ, 2010) state

that Long Branch is impaired based on assessments at biological station 2-

LOB000.37. Seasonal difference was noted for the biological sampling and the

source of impairment is described as “Unknown”.

Buffalo River was originally listed as impaired due to water quality

violations of the general aquatic life (benthic) standard in the 2008 Virginia Water

Quality Assessment 305(b)/303(d) Integrated Report (VADEQ, 2008). The

Virginia Department of Environmental Quality (DEQ) has identified this

impairment as Cause Group Code H11R-02-BEN, and delineated the benthic

impairment as 1.96 miles on Buffalo River (stream segment VAC-

H11R_BUF04A08). The Buffalo River impaired segment runs from its confluence

with Long Branch downstream to its confluence with Franklin Creek.

Upper Buffalo River

Middle Buffalo River

Lower Buffalo River

ES-3

The DEQ 2010 Fact Sheets for Category 5 Waters (VADEQ, 2010) state

that Buffalo River is impaired based on assessments at biological station 2-

BUF026.43. The fact sheet notes that “Algae dominant, potential nutrient

enrichment. Pasture on left bank, agricultural” and the source of the impairment is

described as “Unknown”.

Applicable Water Quality Standard and Designated Use Pollution from both point and nonpoint sources can lead to a violation of

Virginia’s General Standard (9 VAC 25-260-20). A violation of this standard is

assessed on the basis of measurements of the in-stream benthic macro-

invertebrate community. Water bodies having a benthic impairment are not fully

supportive of the aquatic life designated use for Virginia’s waters (9 VAC 25-260-

10).

Benthic Stressor Analysis

Every TMDL is pollutant-specific. Since a benthic impairment is based on

a biological inventory, rather than on a physical or chemical water quality

parameter, the pollutant is not explicitly identified in the assessment, as it is with

physical and chemical parameters. The process outlined in USEPA’s Stressor

Identification Guidance Document (USEPA, 2000) was used to identify the critical

stressors for the impaired stream segments in this study.

Based on the stressor analysis (Kline et al., 2013), the most probable

stressor contributing to the impairment of the benthic community in Long Branch

and Buffalo River is sediment. Sediment is supported as the most probable

stressor based on the consistently poor habitat sediment metrics. Habitat metric

scores for bank vegetative protection in Buffalo River and sediment deposition in

both Long Branch and Buffalo River have been consistently poor throughout the

sampling period. Additionally, historical livestock access to the stream point to

sediment as the most probable stressor. Therefore, sediment TMDLs will be

developed to address the Long Branch and Buffalo River biological impairments.

ES-4

Sediment Modeling Approach

Since there are no in-stream water quality standards for sediment in

Virginia, an alternate method was needed to establish a reference endpoint to

represent the “non-impaired” condition. For these watersheds, the “reference

watershed” approach was used to set allowable loading rates in the impaired

watersheds.

The reference watershed approach pairs two watersheds – one whose

streams are supportive of their designated uses and one whose streams are

impaired (Yagow, 2004). The reference watershed is selected on the basis of

similarity of land use, topography, ecology, and soils characteristics with those of

the impaired watershed. This approach is based on the assumption that reduction

of the stressor loads in the impaired watershed to the level of loads in the

reference watershed will result in elimination of the benthic impairment. Fishpond

Creek was selected as the reference watershed for both impaired watersheds.

Using the Generalized Watershed Loading Functions (GWLF) model as

modified by Yagow and Hession (2007), inputs were created for Long Branch,

Buffalo River and Fishpond Creek watersheds. The TMDL endpoints were

defined as the simulated load from Fishpond Creek, area-adjusted separately to

the Long Branch and Buffalo River watersheds. The GWLF model was run in

metric units and converted to English units for this report.

Accounting for Critical Conditions and Seasonal Variations

EPA regulations at 40 CFR 130.7 (c)(1) require TMDLs to take into

account critical conditions for stream flow, loading, and water quality parameters.

These conditions were considered in this study through the use of long-term (19

years) rainfall and temperature inputs to GWLF that covered different flow

regimes and weather variability.

The GWLF model is a continuous simulation model that uses daily time

steps for weather data and water balance calculations. The period of rainfall

selected for modeling was chosen as a multi-year period that was representative

ES-5

of typical weather conditions for the area, and included “dry”, “normal” and “wet”

years. The model, therefore, incorporated the variable inputs needed to represent

critical conditions during low flow – generally associated with point source loads –

and critical conditions during high flow – generally associated with nonpoint

source loads.

The GWLF model used for this analysis considered seasonal variation

through a number of mechanisms. Daily time steps were used for weather data

and water balance calculations. The model also used monthly-variable parameter

inputs for evapo-transpiration cover coefficients, daylight hours/day, and rainfall

erosivity coefficients for user-specified growing season months.

Simulated Sediment Loads

Sediment loads were simulated for all individual land uses with the GWLF

model, calculated for point sources (using permitted and/or simulated sediment

and discharge data), and then summed in the Long Branch, Buffalo River and the

area-adjusted reference Fishpond Creek watersheds for Existing conditions.

Future residential development is expected to be minimal. As no major

changes are envisioned for the watersheds, future land use in the watersheds

was represented at the existing conditions. The only differences in loads for the

Future scenario were that loads from permitted sources were calculated at their

WLA permit limits, and those loads were then subtracted from their associated

barren or developed land use categories. Table ES-1 includes sediment loads by

land use from Future conditions for the Long Branch and Buffalo River

watersheds and the area-adjusted existing loads for the reference watershed,

Fishpond Creek.

ES-6

Table ES-1. Existing and Future Sediment Loads

BUF LOB FSPadjBUF FSPadjLOBBuffalo River

Long Branch

Fishpond Creek - adjusted to BUF

Fishpond Creek - adjusted to LOB

Sediment Load (tons/yr)HiTill Rowcrop (hit) 83.7 13.4 188.9 20.4LoTill Rowcrop (lot) 26.3 4.2 97.1 10.5Pasture (pas_g) 43.0 7.2 215.1 23.2Pasture (pas_f) 1,382.2 234.4 1,362.0 146.9Pasture (pas_p) 753.4 130.4 240.7 26.0Riparian pasture (trp) 2,005.1 388.5 992.2 106.9AFO (afo) 0.0 0.0 0.0 0.0Hay (hay) 271.8 71.9 807.8 87.1Forest (for) 1,261.3 108.8 692.0 74.6Harvested forest (hvf) 101.0 8.6 54.3 5.8Transitional (barren) 446.0 26.8 185.3 20.0Pervious LDI (pur_LDI) 234.5 14.2 121.0 13.0Pervious MDI (pur_MDI) 0.3 0.1 0.0 0.0Pervious HDI (pur_HDI) 0.0 0.0 0.0 0.0Impervious LDI (imp_LDI) 3.4 0.2 0.7 0.0Impervious MDI (imp_MDI) 0.9 0.1 0.0 0.0Impervious HDI (imp_HDI) 0.1 0.0 0.0 0.0Channel Erosion 122.1 0.9 190.9 1.0Permitted Sources 306.4 16.2 0.0 0.0Total Sediment Load 7,041.6 1,025.9 5,147.9 535.4

Land Use/Source Categories

Future Existing

The Sediment TMDLs for Long Branch and Buffalo River

The sediment TMDLs for Long Branch and Buffalo River were calculated

using the following equation:

TMDL = ∑WLA + ∑LA + MOS

where ∑WLA = sum of the wasteload (permitted) allocations;

∑LA = sum of load (nonpoint source) allocations; and

MOS = margin of safety.

The sediment TMDL loads for Long Branch and Buffalo River watersheds

were defined as the average annual sediment loads from the non-impaired

Fishpond Creek watershed, area-adjusted to each impaired watershed.

ES-7

The WLA is comprised of sediment loads from aggregates of both general

permits and construction permits. No additional explicit Future Growth WLA was

included. However, the simulated future condition accounted for anticipated

construction WLA needs, whose long-term average area was calculated as a

percentage of developed acreage, rather than the current permitted acreage.

An explicit 10% MOS was used in the TMDL calculation based on best

professional judgment and the precedence of other TMDLs developed using the

reference watershed approach for biological impairments due to sediment in

Virginia.

The LA was calculated as the TMDL minus the sum of WLA and MOS.

The Long Branch and Buffalo River TMDL loads and components are shown in

Table ES-2 and Table ES-3.

Table ES-2. The Long Branch and Buffalo River Sediment TMDLs

Table ES-3. Long Branch and Buffalo River Maximum “Daily” Sediment Loads

Long Branch: VAC-H11R_LOB01A04; Cause Group Code H11R-01-BENMDL LA MOS

5.04 4.50 0.50construction aggregate WLA 0.044 tons/day

Buffalo River: VAC-H11R_BUF04A08; Cause Group Code H11R-02-BENMDL LA MOS

47.58 41.99 4.75construction aggregate WLA 0.829 tons/daygeneral permits aggregate WLA 0.01 tons/day

WLA(tons/day)

0.839

WLA

0.044(tons/day)

ES-8

Allocation Scenarios

The target sediment load for each watershed allocation scenario is the

TMDL minus the MOS. Allocation scenarios were created by applying percent

reductions to the various land use/source categories until the target allocation

load was achieved.

Two allocation scenarios were created for each impaired watershed and

reviewed by local stakeholders, Table ES-4 and Table ES-5. Harvested Forest

BMPs are typically required for all commercially harvested areas, but are not

always implemented in small-lot harvests. In the Future load, these BMPs were

represented as being partially (30%) effective, while for both allocation scenarios,

these BMPs were simulated as being 60% effective (efficiency used in the

Chesapeake Bay Watershed Model; USEPA, 2010). Scenario 1 applies equal

percent reductions from all land uses and sources, except forest, harvested

forest, and point sources. Scenario 2 applies equal percent reductions from the

largest source (pasture) and the “developed” land use, along with the harvested

forest BMPs. These scenarios represent two strategies that can be refined by a

local TMDL Implementation Planning committee, as they consider applicable

BMPs, costs, and available funding sources for site-specific implementation.

Table ES-4. Sediment TMDL Load Allocation Scenarios, Long Branch

ES-9

Table ES-5. Sediment TMDL Load Allocation Scenarios, Buffalo River

Reduction

Load

Reduction

Load

Row Crops 172.1 39.7% 103.7 172.1Pasture 1,907.3 39.7% 1,149.3 53.1% 893.9Hay 505.7 39.7% 304.7 505.7Forest 62.3 62.3 62.3Harvested Forest 5.0 42.9% 2.8 42.9% 2.8Developed 114.3 39.7% 68.9 53.1% 53.5Channel Erosion 3.5 39.7% 2.1 3.5Permitted WLA 115.6 115.6 115.6Total Load 2,885.6 1,809.4 1,809.4Target Allocation Load = 1,809.4% Reduction Needed = 37.3%

Scenario 1 Scenario 2Land Use/ Source

Group

Future Sediment Load

(tons/yr)

Reasonable Assurance for Implementation

Several factors provide assurance that the TMDLs will be implemented.

Virginia intends for the required sediment reductions to be implemented in an

iterative process that first addresses those sources with the largest impact on

water quality. DEQ will monitor benthic macro-invertebrates and habitat in

accordance with its biological monitoring program at station 2-LOB000.37 on

Long Branch and station 2-BUF026.43 on Buffalo River. DEQ will continue to use

data from these monitoring stations to evaluate improvements in the benthic

communities and the effectiveness of TMDL implementation in attainment of the

general water quality standard.

Additionally, a TMDL implementation plan will be developed and

implemented in accordance with requirements of the Virginia’s 1997 Water

Quality Monitoring, Information and Restoration Act (WQMIRA).

Implementation of BMPs to address the benthic impairments in Long

Branch and Buffalo River will be coordinated with BMPs required to meet bacteria

water quality standards in a concurrent TMDL being developed for the Buffalo

River watershed.

Public participation was elicited at every stage of the TMDL development

in order to receive inputs from stakeholders and to apprise the stakeholders of

ES-10

the progress made. Three Technical Advisory Committee (TAC) meetings and

two public meetings were organized for this purpose. All meetings were held at

the Central Virginia Community College in Amherst, Virginia.

The first Technical Advisory Committee (TAC) Meeting was held on June

14, 2012 to introduce agency stakeholders to the TMDL process and to discuss

the impairments identified on stream segments in these watersheds. The first

public meeting on June 25, 2012 introduced the public to the TMDL process and

the local impairments on Long Branch and Buffalo River. A second TAC meeting

was held in the form of a teleconference to discuss the stressor analysis, while

the third TAC meeting discussed modeling procedures and the draft TMDL. The

final public meeting was held on April 25, 2013 to present the draft TMDL report

to address the benthic impairment in the Long Branch and Buffalo River

watersheds. The public comment period ended on June 13, 2013. No comments

were received.

Long Branch and Buffalo River Sediment TMDLs Amherst County, Virginia

1

Chapter 1: INTRODUCTION

1.1. Background

1.1.1. TMDL Definition and Regulatory Information

Section 303(d) of the Federal Clean Water Act and the U.S. Environmental

Protection Agency’s (USEPA) Water Quality Planning and Management Regulations

(40 CFR Part 130) require states to identify water bodies that violate state water

quality standards and to develop Total Maximum Daily Loads (TMDLs) for such

water bodies. A TMDL reflects the pollutant loading a water body can receive and

still meet water quality standards. A TMDL establishes the allowable pollutant

loading from both point and nonpoint sources for a water body, allocates the load

among the pollutant contributors, and provides a framework for taking actions to

restore water quality.

1.1.2. Impairment Listing

The subjects of this TMDL study are two impaired stream segments in the

Buffalo River watershed: one segment in Long Branch, a tributary to Buffalo River;

and one segment on Buffalo River. These impaired segments are located within

Amherst County in the Commonwealth of Virginia, Figure 1-1. The watersheds

delineated to simulate sediment loading to these impaired segments are also shown

in Figure 1-1 and will herein be referred to as the TMDL watersheds.

Long Branch was originally listed as impaired due to water quality violations of

the general aquatic life (benthic) standard in the 2008 Virginia Water Quality

Assessment 305(b)/303(d) Integrated Report (VADEQ, 2008). The Virginia

Department of Environmental Quality (DEQ) has identified this impairment as Cause

Group Code H11R-01-BEN, and delineated the benthic impairment as 3.40 miles on

Long Branch (stream segment VAC-H11R_LOB01A04). The Long Branch impaired

segment runs from the headwaters downstream to its confluence with Buffalo River.


2

Figure 1-1. Location of Impaired Segments and TMDL Watersheds

The DEQ 2010 Fact Sheets for Category 5 Waters (VADEQ, 2010) state that

Long Branch is impaired based on assessments at biological station 2-LOB000.37.

Seasonal difference was noted for the biological sampling and the source of

impairment is described as “Unknown”.

Buffalo River was originally listed as impaired due to water quality violations

of the general aquatic life (benthic) standard in the 2008 Virginia Water Quality

Assessment 305(b)/303(d) Integrated Report (VADEQ, 2008). The Virginia

Department of Environmental Quality (DEQ) has identified this impairment as Cause

Group Code H11R-02-BEN, and delineated the benthic impairment as 1.96 miles on

Buffalo River (stream segment VAC-H11R_BUF04A08). The Buffalo River impaired


3

segment runs from its confluence with Long Branch downstream to its confluence

with Franklin Creek.

The DEQ 2010 Fact Sheets for Category 5 Waters (VADEQ, 2010) state that

Buffalo River is impaired based on assessments at biological station 2-BUF026.43.

The fact sheet notes that “Algae dominant, potential nutrient enrichment. Pasture on

left bank, agricultural” and the source of the impairment is described as “Unknown”.

1.1.3. Pollutants of Concern Pollution from both point and nonpoint sources can lead to a violation of the

benthic standard. A violation of this standard is assessed on the basis of

measurements of the in-stream benthic macro-invertebrate community. Water

bodies having a benthic impairment are not fully supportive of the aquatic life

designated use for Virginia’s waters.

1.2. Designated Uses and Applicable Water Quality Standards

1.2.1. Designation of Uses (9 VAC 25-260-10) “A. All state waters are designated for the following uses: recreational uses (e.g. swimming and boating); the propagation and growth of a balanced indigenous population of aquatic life, including game fish, which might reasonably be expected to inhabit them; wildlife; and the production of edible and marketable natural resources (e.g., fish and shellfish).” SWCB, 2011.

1.2.2. General Standard (9 VAC 25-260-20)

The general standard for a water body in Virginia is stated as follows:

“A. All state waters, including wetlands, shall be free from substances attributable to sewage, industrial waste, or other waste in concentrations, amounts, or combinations which contravene established standards or interfere directly or indirectly with designated uses of such water or which are inimical or harmful to human, animal, plant, or aquatic life.

Specific substances to be controlled include, but are not limited to: floating debris, oil scum, and other floating materials; toxic substances (including those which bioaccumulate); substances that produce color, tastes, turbidity, odors, or settle to form sludge


4

deposits; and substances which nourish undesirable or nuisance aquatic plant life. Effluents which tend to raise the temperature of the receiving water will also be controlled.” SWCB, 2011.

The biological monitoring program in Virginia that is used to evaluate

compliance with the above standard is administered by the Virginia Department of

Environmental Quality (DEQ). Evaluations of monitoring data from this program

focus on the benthic (bottom-dwelling) macro (large enough to see) invertebrates

(insects, mollusks, crustaceans, and annelid worms) and are used to determine

whether or not a stream segment has a benthic impairment. Changes in water

quality generally result in alterations to the quantity and diversity of the benthic

organisms. Besides being the major intermediate constituent of the aquatic food

chain, benthic macro-invertebrates are "living recorders" of past and present water

quality conditions. This is due to their relative immobility and their variable resistance

to the diverse contaminants that are introduced into streams. The community

structure of these organisms provides the basis for the biological analysis of water

quality. Two types of biological monitoring, both qualitative and semi-quantitative,

have been conducted by DEQ since the early 1970's. The U.S. Environmental

Protection Agency’s (USEPA) Rapid Bioassessment Protocol (RBP) II was employed

beginning in the fall of 1990 to utilize a standardized, repeatable assessment

methodology (Barbour et al., 1999). For any single sample, the RBP II produces

water quality ratings of “non-impaired,” “slightly impaired,” “moderately impaired,” or

“severely impaired.” In Virginia, benthic samples are typically collected and analyzed

twice a year in the spring and in the fall.

The RBP II procedure evaluates the benthic macro-invertebrate community by

comparing ambient monitoring “network” stations to “reference” sites. A reference

site is one that has been determined to be representative of a natural, non-impaired

water body. The RBP II evaluation also accounts for the natural variation noted in

streams in different eco-regions. One additional product of the RBP II evaluation is a

habitat assessment. This is a stand-alone assessment that describes bank condition

and other stream and riparian corridor characteristics and serves as a measure of

habitat suitability for the benthic community.


5

Beginning in 2006, DEQ modified their bioassessment procedures. While the

RBP II protocols were still followed for individual metrics, a new index, the Virginia

Stream Condition Index (VSCI), was developed based on comparison of observed

data to a set of reference conditions, rather than with data from a single reference

station. The new index was also calculated for all previous samples in order to better

assess trends over time.

Determination of the degree of support for the aquatic life designated use is

based on biological monitoring data and the best professional judgment of the DEQ

regional biologist, relying primarily on the most recent data collected during the

current 6-year assessment period. In Virginia, any stream segment with a benthic

score less than the impairment threshold is placed on the state’s 303(d) list of

impaired streams (VADEQ, 2012).


6

Chapter 2: WATERSHED CHARACTERIZATION

2.1. Water Resources

The Buffalo River watershed is part of the James River basin and comprises part

of state hydrologic unit H11 (National Watershed Boundary Dataset JM28). The

impaired segment of Buffalo River lies entirely within Amherst County. The Upper

Buffalo River drainage area is comprised of the North Fork and South Fork of the Buffalo

River. The Forks of the Buffalo River flow into the Middle Buffalo River drainage area.

The Middle Buffalo River flows south southeast to its confluence with Long Branch,

which is the beginning of the impaired segment of the Buffalo River. Long Branch flows

east and discharges into Buffalo River. The Lower Buffalo River drainage area contains

the impaired segment of the Buffalo River from its confluence with Long Branch to its

confluence with Franklin Creek. Buffalo River discharges into Tye River. Tye River is a

tributary of the James River Basin, which flows into the Chesapeake Bay.

2.2. Eco-region

The Long Branch watershed is located entirely within the Northern Inner

Piedmont (45e) sub-division of the Piedmont (45) ecoregion, and the Buffalo River

watershed is located within the Northern Inner Piedmont (45e) sub-division and the

Northern Igneous Ridges (66a) sub-division of the Blue Ridge (66) ecoregion. Ecoregion

45e is a dissected upland composed of hills, irregular plains, and isolated ridges and

mountains. General elevations become higher towards the western boundary and to the

south where the land rises to become a broad, hilly upland. Ecoregion 45e is

characteristically underlain by highly deformed and deeply weathered Cambrian and

Proterozoic feldspathic gneiss, schist, and melange. Streams have silt, sand, gravel,

and rubble bottoms materials and bedrock is only occasionally exposed. Differences in

stream gradient considerably affect fish habitat in the Piedmont. Loblolly – shortleaf pine

forests are common (USEPA, 2002). Ecoregion 66a consists of pronounced ridges

separated by high gaps and coves. Mountain flanks are steep and well dissected.

Precambrian and Paleozoic metavolcanic and igneous rock underlie Ecoregion 66a.


7

Streams are cool and clear and have many riffle sections. The natural vegetation was

Appalachian Oak Forest and Ecoregion 66a remains extensively forested.

2.3. Soils and Geology

The Long Branch watershed is comprised of a diversity of soils with its dominant

soil, Clifford fine sandy loam, comprising 51.2% of the watershed. The next most

abundant soil type is Rhodhiss sandy loam at 32.1%. The Clifford series (fine, kaolinitic,

mesic Typic Kanhapludults) consists of very deep, well-drained, moderately permeable

soils. They formed in residuum weathered from felsic crystalline rocks of the Piedmont

uplands. The Rhodhiss series (fine-loamy, mixed, semiactive, mesic Typic Hapludults)

consists of very deep, well-drained, moderately permeable soils. They also formed in

residuum weathered from felsic crystalline rocks of the Piedmont uplands (USDA-

NRCS, 2012).

The Buffalo River watershed is comprised of a diversity of soils with its dominant

soil, Edneytown sandy loam, comprising 28.9% of the watershed. The next most

abundant soil types are Rhodhiss sandy loam, Clifford fine sandy loam, and Peaks

gravelly loam at 17.0%, 16.8%, 14.9%, respectively. The Edneytown series (fine-loamy,

mixed, active, mesic Typic Hapludults) consists of very deep, well drained, moderately

permeable soils on ridges and side slopes of the Blue Ridge. They formed in residuum

weathered from felsic to mafic, igneous and high-grade metamorphic rocks. The Peaks

series (loamy-skeletal, mixed, active, mesic Typic Dystrudepts) are moderately deep,

somewhat excessively drained, rapidly permeable soils on ridge tops and convex slopes

in the Blue Ridge province (USDA-NRCS, 2012).

2.4. Climate

Climate data for the Buffalo River watershed was based on meteorological

observations made by the Pedlar Dam National Climatic Data Center station (446593)

located in Amherst County, Virginia, approximately 5.8 miles northwest from the Long

Branch outlet into Buffalo River. Average annual precipitation at this station is 44.73

inches; while the average annual daily temperature is 55.4°F. The highest average daily

temperature of 85.2°F occurs in July while the lowest average daily temperature of


8

25.2°F occurs in January, as obtained for the period of record: 11/1/1926 to 4/30/2012

(SERCC, 2013).

2.5. Land Use

The initial set of land use categories for the Buffalo River watershed was derived

from the 2009 National Agricultural Statistics Service cropland data layer (USDA-NASS,

2009) for Virginia. The distribution of detailed NASS land use acreages in the watershed

is given in Table 2-1, and generalized categories of land use are shown in Figure 2-1.

These categories were modified for subsequent sediment modeling, as described later

in Chapter 5.

Figure 2-1. NASS Generalized Land Use in the Buffalo River Watershed


9

Table 2-1. NASS Land Use Summary in Buffalo River Watersheds (acres)

NASS Land Use Categories

Upper Buffalo

River

Middle Buffalo

RiverLong

Branch

Lower Buffalo

RiverBuffalo

River TotalCorn 4.21 2.67 0.51 91.52 98.90Soybeans 0.52 8.23 1.11 13.35 23.21Barley 0.00 0.22 0.00 0.00 0.22Winter Wheat 0.00 0.67 0.00 0.22 0.89W. Wht./Soy. Dbl. Crop 0.00 0.22 0.00 0.00 0.22Oats 0.00 0.22 0.00 0.00 0.22Alfalfa 1.53 0.00 0.00 0.44 1.98Other Hays 28.10 194.80 36.96 319.29 579.15Fallow/Idle Cropland 1.18 9.76 0.22 3.03 14.19Pasture/Grass 382.42 427.47 210.43 951.46 1971.78NLCD - Open Water 0.00 0.00 0.44 3.04 3.49NLCD - Developed/Open Space 403.08 166.95 32.60 301.38 904.01NLCD - Developed/Low Intensity 16.15 30.90 3.32 21.29 71.66NLCD - Developed/Medium Intensit 0.00 2.09 0.34 0.67 3.10NLCD - Developed/High Intensity 0.00 0.59 0.00 0.00 0.59NLCD - Barren 1.56 0.00 0.00 0.36 1.92NLCD - Deciduous Forest 9072.54 2567.92 1106.76 5894.99 18642.20NLCD - Evergreen Forest 139.63 74.87 83.95 93.79 392.24NLCD - Mixed Forest 30.18 6.43 13.80 14.22 64.63NLCD - Shrubland 0.36 0.52 1.10 15.89 17.88NLCD - Grassland Herbaceous 14.73 14.74 34.12 29.39 92.97Dbl. Crop WinWht/Corn 0.00 0.67 0.00 0.00 0.67Dbl. Crop Barley/Corn 0.00 0.89 0.00 0.59 1.48Dbl. Crop Soybeans/Oats 0.00 3.03 0.00 0.00 3.03Total Area (acres) 10096.20 3513.84 1525.65 7754.93 22890.62Broad Land Use Distribution

% Forest 91.5% 75.4% 79.0% 77.6% 83.5%% Developed 4.2% 5.7% 2.4% 4.2% 4.3%

% Pasture/Hay 3.9% 12.6% 16.0% 12.6% 9.0%% Cropland 0.4% 6.3% 2.6% 5.6% 3.2%


10

2.6. Biological Monitoring Data – Benthic Macro-invertebrates

Biological monitoring consisted of sampling the benthic macro-invertebrate

communities along with corresponding habitat assessments. The data for the

bioassessments in Long Branch and Buffalo River were based on DEQ biological

monitoring at two DEQ monitoring sites in the watersheds. The locations of the DEQ

biological monitoring stations are shown in Figure 2-2. Monitoring station 2-LOB000.37,

near the outlet of Long Branch was monitored in 2001 and 2009-2011, station 2-

BUF030.41was monitored twice in 2011, and station 2-BUF026.43, near the confluence

with Franklin Creek was monitored in 2002, 2006 and 2009-2011.

Figure 2-2. Location of DEQ Monitoring Stations in the Buffalo River Watershed


11

Biological samples were collected from the best available habitat using riffle or

multi-habitat methods. The samples were then preserved and subsorted, and then the

organisms were identified to the family and/or genus taxonomic level.

In 2006, DEQ upgraded its biomonitoring and biological assessment methods to

those currently recommended by USEPA Region 3 for the mid-Atlantic region. As part of

this effort, a study was performed to assist the agency in moving from a paired-

network/reference site approach based on the RBP II to a regional reference condition

approach, and has led to the development of the Virginia Stream Condition Index (VSCI)

for Virginia’s non-coastal areas (Tetra Tech, 2003). This multi-metric index is based on 8

biomonitoring metrics, with a scoring range of 0-100, that include some different metrics

than those used previously in the RBP II, but are based on the same taxa inventory. A

maximum score of 100 represents the best benthic community sites. The current criteria

define “non-impaired” sites as those with a VSCI of 60 or above, and “impaired” sites as

those with a score below 60 (VADEQ, 2006).

Long Branch A full listing of the benthic macro-invertebrate taxa inventory or distribution within

each Long Branch biological sample is given in Table 2-2. Across all samples, the most

dominant family of benthic macro-invertebrates is the pollution-tolerant Chironimidae

(A), ranked highest in seven of the eight samples. In the other sample, the dominant

family was a more pollution-sensitive family, indicative of better water quality. Individual

VSCI metrics and scores are given in Table 2-3, and a graph of the VSCI scores over

time are displayed in Figure 2-3. The primary biological effects are identified as those

metrics scoring in the lowest 20th percentile. The primary biological effects in Long

Branch, indicative of its relatively minor impairment, are the occasional low scores for

the scraper functional group and the sensitive members of the Plecoptera (stoneflies)

and Tricoptera (case maker caddisflies) families.


12

Table 2-2. Taxa Inventory by Sample Date in Long Branch (LOB)

06/05/01 10/22/01 04/09/09 09/30/09 04/06/10 10/18/10 03/29/11 11/08/11Glossosomatidae 0 1Leuctridae 0 1 1Capniidae 1 5 19Gomphidae 1 1 1 2 3 1Athericidae 2 1Isonychiidae 2 3Nemouridae 2 7 6Perlodidae 2 2 2 4Taeniopterygidae 2 9 5 13Philopotamidae 3 6 10 1 16 5Tipulidae 3 2 3 2 3 1Uenoidae 3 2 1Baetidae 4 2 3 6 2 1 2Elmidae 4 1 6 2 4 24 5 11Ephemerellidae 4 12 31 3 24 14 2Heptageniidae 4 7 20 5 48 6 2 5Psephenidae 4 1Calopterygidae 5 1Corydalidae 5 1 3 2 1Ptilodactylidae 5 1

5 1Ancylidae 6 2 1 1Chironomidae (A) 6 71 14 49 1 30 28 55 33Empididae 6 1 2Hydropsychidae 6 2 52 2 31 7 11 2 10Polycentropodidae 6 1Simuliidae 6 1 2 3 9 3Tabanidae 6 1Unknown 6 6Corbiculidae 8 1

(blank) 16 4 533 53 49 64 61 61 48 63

No. of species 8 10 9 10 18 14 17 13Abundance 98 113 100 104 110 110 110 110Additional Benthic MetricsScraper/Filterer-Collector 9.2% 36.1% 5.4% 106.1% 11.4% 51.7% 8.5% 32.7%%Filterer-Collector 88.8% 63.7% 92.0% 47.1% 63.6% 54.5% 74.5% 50.0%%Haptobenthos 22.4% 74.3% 42.0% 96.2% 40.0% 58.2% 33.6% 34.5%%Shredder 2.0% 10.6% 0.0% 0.0% 9.1% 12.7% 7.3% 29.1%

- Dominant 2 species in each sample.VSCI: Optimal > 60; suboptimal < 50.

Family Tolerance Value

VSCI

2-LOB000.37


13

Table 2-3. Biological Index (VSCI) Scores for Long Branch (LOB)

StationIDCollDate 06/05/01 10/22/01 04/09/09 09/30/09 04/06/10 10/18/10 03/29/11 11/08/11VSCI Metric ValuesFamTotTaxa 10 11 12 10 18 14 17 13FamEPTTax 4 5 7 5 9 6 7 8%Ephem 17.9 18.4 32.8 51.9 27.3 7.3 15.5 8.2%PT - Hydropsychidae 13.2 11.8 9.6 12.7 23.6 10.0 34.5Fam%Scrap 6.8 22.8 4.2 50.0 7.3 28.2 6.4 16.4%Chiro 60.7 12.3 41.2 1.0 27.3 25.5 50.0 30.0Fam%2Dom 71.8 63.2 67.2 76.0 49.1 47.3 62.7 47.3FamHBI 5.8 4.9 4.9 4.5 4.5 4.3 5.1 4.0VSCI Metric Scores%Ephem Score 29.3 30.1 53.5 84.7 44.5 11.9 25.2 13.3%PT-H Score 0.0 37.0 33.0 27.0 35.8 66.4 28.1 97.0%Chironomidae Score 39.3 87.7 58.8 99.0 72.7 74.5 50.0 70.0Fam Richness Score 45.5 50.0 54.5 45.5 81.8 63.6 77.3 59.1Fam EPT Score 36.4 45.5 63.6 45.5 81.8 54.5 63.6 72.7Fam %Scraper Score 13.3 44.2 8.1 96.9 14.1 54.6 12.3 31.7Fam %2Dom Score 40.8 53.2 47.4 34.7 73.6 76.2 53.9 76.2Fam %MFBI Score 62.5 75.2 75.0 80.2 81.4 83.4 72.3 87.5VSCI 33.4 52.9 49.3 64.2 60.7 60.7 47.8 63.5

VSCI RatingSevere Stress

Stressed Stressed Good Good Good Stressed Good

- Primary biological effects.

2-LOB000.37

Figure 2-3. VSCI Scores for Long Branch (LOB)

Non-impaired

Impaired


14

Buffalo River A full listing of the benthic macro-invertebrate taxa inventory or distribution within

each Buffalo River biological sample is given in Table 2-4. Across all samples at station

2-BUF026.48, in the impaired segment of Buffalo River, The dominant family of benthic

macro-invertebrates are the pollutant-tolerant Chironomidae and Hydropsychidae, with

occasional dominance by one of the more pollutant-sensitive families. Individual VSCI

metrics and scores are given in Table 2-5, and a graph of the VSCI scores over time are

displayed in Figure 2-4. The primary biological effects are identified as those metrics

scoring in the lowest 20th percentile. The primary biological effects in Buffalo River,

indicative of its relatively minor impairment, are the occasional low scores for sensitive

members of the Plecoptera (stoneflies) and Tricoptera (case maker caddisflies) families,

very similar to those in Long Branch.


15

Table 2-4. Taxa Inventory by Sample Date in Buffalo River (BUF)


16

Table 2-5. Biological Index (VSCI) Scores for Buffalo River (BUF)

Figure 2-4. VSCI Scores for Buffalo River (BUF)

Non-impaired


17

2.7. Biological Monitoring Data – Habitat

A qualitative analysis of various habitat parameters was conducted in conjunction

with each benthic macro-invertebrate sampling event. Habitat data collected as part of

the biological monitoring were obtained from DEQ through the EDAS database. For

each evaluation, ten metrics are scored 0-20 using EPA rapid biosassessment protocols

(Barbour et al., 1999). Scores of 0-5 are rated “poor”; 6-10 are “marginal”; 11-15 are

“sub-optimal”; and 16-20 are “optimal”, with minor variations for those metrics scored

separately for each stream bank. The maximum 10-metric total habitat score is 200;

scores <120 are considered sub-optimal, and those >150 are optimal. The 10 metrics

evaluated vary based on whether the best available habitat was dominated by riffle or

multi-habitat (snags, leaf packs). The former is considered “high gradient” and the latter

“low gradient.”

The habitat assessment data for Long Branch are shown in Table 2-6. The only

metric with consistently low scores is the “sediment deposition” metric. The total habitat

scores are all in the moderate range.

Table 2-6. Habitat Metric Scores for Long Branch (LOB)

StationID

Collection Date 06/0

5/01

10/2

2/01

04/0

9/09

09/3

0/09

04/0

6/10

10/1

8/10

03/2

9/11

11/0

8/11

Channel Alteration 20 20 16 17 16 18 17 17Bank Stability 19 16 15 15 11 9 11 15Vegetative Protection 15 18 15 17 12 9 11 15Embeddedness 12 14 11 8 10 10 12 11Channel Flow Status 15 12 13 10 18 14 15 15Frequency of riffles (or bends) 20 16 17 13 17 17 16 18Riparian Vegetative Zone Width 12 12 11 10 10 10 10 11Sediment Deposition 9 10 10 8 9 8 10 10Epifaunal Substrate / Available Cover 13 13 18 11 16 11 16 17Velocity / Depth Regime 15 15 15 15 17 17 16 1510-Metric Total Habitat Score 150 146 141 124 136 123 134 144

- Marginal or Poor habitat metric rating.Habitat Score: optimal > 150; suboptimal < 120.

2-LOB000.37

The habitat assessment data for Buffalo River are shown in Table 2-7. Although

there are a number of poor or marginal individual metric scores scattered about, the


18

total habitat scores are all moderate with a couple in the “optimal” range, also indicative

of a minor impairment.

Table 2-7. Habitat Metric Scores for Buffalo River (BUF)

2.8. Water Quality Data

2.8.1. DEQ Ambient Monitoring Data Ambient bi-monthly monitoring was performed at station 2-LOB000.37 on the

Long Branch impaired segment in 2010-2011. During 2010, ambient bi-monthly

monitoring was performed on the Buffalo River impaired segment at station 2-

BUF026.43, which changed to monthly monitoring during 2011. Ambient monthly

monitoring was also performed at 2-BUF026.53 in 2011. Field physical parameters

included temperature, DO, pH, and conductivity. Chemical parameters include: nitrogen

(N) species – ammonia-N, nitrate-N, nitrite-N, TKN, and total N; total phosphorus (P);

total filterable residue (suspended solids); and Escherichia coli. Average nutrient

concentrations from the three stations are summarized in Table 2-8, along with two

calculated ratios to assist in assessing nutrient influences in these watersheds.


19

Table 2-8. Nutrient Concentration Averages and Ratios

No. Ave. No. Ave. No. Ave. No. Ave. No. Ave. No. Ave.2-LOB000.37 2010-2011 12 0.47 12 0.03 12 0.01 12 0.17 12 0.25 12 0.06 8.23 0.542-BUF026.43 2010-2011 25 0.52 14 0.01 14 0.01 14 0.34 14 0.21 28 0.05 9.67 0.402-BUF026.53 2011 12 0.54 12 0.01 12 0.01 12 0.29 12 0.23 12 0.04 13.38 0.44

Station Period TN:TP Ratio

TKN:TN Ratio

TN NH3-N NO2-N NO3-N TKN TP

2.8.2. DEQ Stream Tests for Metals and Organic Compounds One sediment sample was collected in Long Branch on October 22, 2001 and

analyzed by DEQ for a standard suite of metals.

None of the analytes exceeded any established consensus-based probable

effects concentration (PEC) screening criteria, and most of the metals were not detected

above their respective minimum detection limit (MDL), Table 2-9.

Table 2-9. DEQ Channel Bottom Sediment Monitoring and Screening Criteria for Metals

Station ID: Collection Date Time: TEC PEC

Name ValueComment

Code (mg/kg) (mg/kg)ARSENIC IN BOTTOM DEPOSITS (MG/KG AS AS DRY WGT) 5 U 9.79 33BERYLLIUM IN BOTTOM DEPOSITS(MG/KG AS BE DRY WGT) 5 UCADMIUM,TOTAL IN BOTTOM DEPOSITS (MG/KG,DRY WGT) 1 U 0.99 4.98CHROMIUM,TOTAL IN BOTTOM DEPOSITS (MG/KG,DRY WGT) 6.2 43.4 111COPPER IN BOTTOM DEPOSITS (MG/KG AS CU DRY WGT) 5 U 31.6 149LEAD IN BOTTOM DEPOSITS (MG/KG AS PB DRY WGT) 12.5 35.8 128MANGANESE IN BOTTOM DEPOSITS (MG/KG AS MN DRY WGT) 261NICKEL, TOTAL IN BOTTOM DEPOSITS (MG/KG,DRY WGT) 5 U 22.7 78.6SILVER IN BOTTOM DEPOSITS (MG/KG AS AG DRY WGT) 1 UZINC IN BOTTOM DEPOSITS (MG/KG AS ZN DRY WGT) 21.4 121 459ANTIMONY IN BOTTOM DEPOSITS (MG/KG AS SB DRY WGT) 5 UALUMINUM IN BOTTOM DEPOSITS (MG/KG AS AL DRY WGT) 5,100SELENIUM IN BOTTOM DEPOSITS (MG/KG AS SE DRY WGT) 1 UIRON IN BOTTOM DEPOSITS (MG/KG AS FE DRY WGT) 10,900THALLIUM DRY WGTBOTMG/KG 5 UMERCURY,TOT IN BOT DEPOS (MG/KG AS HG DRY WGT) 0.1 U 0.18 1.06U = parameter analyzed, but not detectedTEC = Threshold effects concentration - Minimum detection limitPEC = Probable effects concentration

2-LOB000.3710/22/2001

Consensus-Based


20

2.8.3. DEQ – Other Relevant Monitoring or Reports

2.8.3.1 Relative Bed Stability (RBS) Analysis A Log Relative Bank Stability (LRBS) test is a type of siltation index. An LRBS

score of negative one (-1) indicates that sediments ten times larger than the median are

moving at bankfull, with a medium probability of impairment from sediment. A high

percentage of fine sediment in streams would directly contribute to embeddedness, the

filling of the interstitial spaces in the channel bottom. LRBS scores < -1 are considered

sub-optimal, while scores > -0.5 are considered optimal. While Long Branch and Buffalo

River show minimal fine sediment at the stations, both streams have a relatively high

percentage of mean embeddedness (>50%) according to this test, although the percent

of fine material was < 10%. The LRBS score for Long Branch is 0.28 and the LRBS

score for Buffalo River is -0.32, both indicating normal sediment load.

2.8.4. Permitted Point Sources

There are no general discharge permits for single-family homes in the Long

Branch or Buffalo River watersheds.

There are two industrial stormwater general permits (ISWGP) in the Buffalo River

watershed, as shown in Table 2-10.

Table 2-10. Permitted Discharges

Permit No Facility Name Water Body Receiving StreamVAR050404 E F Fitzgerald Lumber VAC-H11R South Fork Buffalo River, UTVAR050411 Ell ington Wood Products Inc VAC-H11R Buffalo River UT

There are, currently, no active land disturbing (construction stormwater) permits

in either the Long Branch or Buffalo River watersheds. However, realizing the

intermittent nature of these permits and their necessity for future growth, the “barren”

land use was represented as 2% of all “developed” land use acreage in the watershed to

reserve a future allocation for this type of permit. Additional local construction permits for

areas < 5 acres in size may also exist for single family construction and other small-

scale construction.


21

Chapter 3: BENTHIC STRESSOR ANALYSIS

3.1. Introduction

A TMDL must be developed for a specific pollutant. Since a benthic impairment is

based on a biological inventory, rather than on a physical or chemical water quality

parameter, the pollutant is not explicitly identified in the assessment, as it is with

physical and chemical parameters. The process outlined in USEPA’s Stressor

Identification Guidance Document (USEPA, 2000) was used to identify the critical

stressor for the each of the impaired stream segments in this study. A list of candidate

causes was developed from the listing information, biological data, published literature,

and stakeholder input. Chemical and physical monitoring data from DEQ provided

additional evidence to support or eliminate the potential candidate causes. Biological

metrics and habitat evaluations in aggregate provided the basis for the initial impairment

listing, but individual metrics were also used to look for links with specific stressors,

where possible. Volunteer monitoring data, land use distribution, Google Earth aerial

imagery (www.google.com/earth/), and visual assessment of conditions in and along the

stream corridor provided additional information to investigate specific potential

stressors. Logical pathways were explored between observed effects in the benthic

community, potential stressors, and intermediate steps or interactions that would be

consistent in establishing a cause and effect relationship with each candidate cause.

The candidate benthic stressors included ammonia, hydrologic modifications, nutrients,

organic matter, pH, sediment, TDS/conductivity/sulfates, temperature, and toxics. The

details of the stressor analyses are included in the Buffalo River and Long Branch

Stressor Analysis Report (Kline et al., 2013), dated April 29, 2013, and the summary is

presented in the following section.

3.2. Stressor Analyses Summaries

The Long Branch (VAC-H11R_LOB01A04) stream segment is impaired, but on

an overall increasing trend for its aquatic life use, with 4 out of 6 recent individual VSCI

sample scores being in the “non-impaired” range. Long Branch is impacted primarily by


22

agricultural land uses. Sediment was selected as the most probable stressor based on

consistently poor scores for the sediment deposition habitat metric.

The Buffalo River (VAC-H11R_BUF04A08) stream segment is only slightly

impaired for its aquatic life use, with individual VSCI scores at station 2-BUF026.43

ranging from 49.2 to 69.8. VSCI scores at station 2-BUF030.41, just above the impaired

segment are in the “non-impaired” range, at 70.9 and 80.0. The impaired segment of

Buffalo River is impacted primarily by agricultural land uses. Sediment was selected as

the most probable stressor based on the poor habitat scores given the lack of riparian

vegetation and sediment deposition. Additionally, historical livestock access to the

stream lends further support to sediment as the most probable stressor.

Therefore, sediment TMDLs will be developed to address the biological

impairments in both Long Branch and Buffalo River.


23

Chapter 4: SETTING REFERENCE TMDL LOADS Since there are no in-stream Water Quality Criteria for sediment in Virginia, an

alternate method was used to establish a reference endpoint that would represent the

“non-impaired” condition. For these watersheds, the “reference watershed” approach

was used to set allowable sediment loading rates in the impaired watersheds.

The reference watershed approach pairs two watersheds – one whose streams

are supportive of their designated uses and one whose streams are impaired. The

reference watershed is selected on the basis of similarity of land use, topography,

ecology, and soils characteristics with those of the impaired watershed. This approach is

based on the assumption that reduction of the stressor loads in the impaired watershed

to the level of the loads in the reference watershed will result in elimination of the

benthic impairment.

After an appropriate reference watershed is selected, models of both the

reference and TMDL watersheds are created, the TMDL endpoint is defined as the

simulated load from the area-adjusted reference watershed, and alternative TMDL

reduction (allocation) scenarios are developed (Yagow, 2004).

4.1. TMDL Reference Watershed Selection

The initial list of potential reference watersheds was composed of watersheds in

the vicinity (approximately a 30-mile radius) of Long Branch and Buffalo River that were

listed as reference sites from DEQ’s probabilistic monitoring program or had been used

previously as reference watersheds by Tetra Tech for the development of the VSCI.

Because sediment was identified as the primary pollutant responsible for the benthic

impairment, the comparison of watershed characteristics focused not only on geological

and ecological similarities, but also on sediment-generating characteristics. Figure 4-1

illustrates the proximity of the potential reference watersheds to the impaired segments.


24

Figure 4-1. Location of Long Branch, Buffalo River and Potential Reference Watersheds

Table 4-1 compares the various physical and sediment-related characteristics of

the potential reference watersheds to the characteristics of Long Branch watershed.

Table 4-2 compares the various physical and sediment-related characteristics of the

potential reference watersheds to the characteristics of Buffalo River watershed. Of

these potential watersheds, the S.F. Falling River watershed was less desirable as it

was not in the same river basin (James River) as the impaired watersheds. All of the

potential reference watersheds also lie at least partially within the Northern Inner

Piedmont (45e) sub-ecoregion, except for the N.F. Buffalo River. The characteristics

chosen to be most representative of sediment generation were land use distribution,

non-forested average soil erodibility (SSURGO K-factor), and non-forested average %

slope.


25

Table 4-1. Comparison of Potential Reference Watershed Characteristics to Long Branch Watershed

Landuse Distribution

Station ID Stream NameArea (ha)

Urban (%)

Forest (%)

Agr (%)

SSURGO K-factor

Slope (%)

Elevation (meters)

Score Date

2-LOB00037 Long Branch 617 6% 77% 18% 0.304 13.25 230.4 63.29 Nov-11 45e James

63.292DFSP00Fishpond Creek 3,601 3% 80% 17% 0.359 10.10 196.8 78.41 Sep-09 45e James2-BVC003.09 Beaver Creek 4,200 5% 89% 6% 0.322 12.24 198.8 73.11 Oct-07 45e/64c James2-RED003.65 Reed Creek 4,229 4% 71% 26% 0.266 10.85 385.2 61.60 May-11 45e/66a James2-BNF003.52 N.F. Buffalo River 3,633 1% 99% 0% 0.273 25.95 909.3 82.74 Nov-10 66a James2-WIC000.40 Wreck Island Creek 15,047 5% 59% 35% 0.270 9.00 210.6 73.53 Sep-00 45e James2-HAZ006.34 Harris Creek 11,002 10% 69% 21% 0.312 11.07 300.2 73.18 Oct-01 45e/66a James4AFSF004.02 SF Falling River 9,810 5% 66% 29% 0.292 8.16 237.6 62.40 Oct-05 45e Roanoke

- Impaired watershed - Closest matches

Potential TMDL Reference Watersheds

Non-Forested Latest SCISubEco Region

River Basin

Impaired Watershed

Table 4-2. Comparison of Potential Reference Watershed Characteristics to Buffalo

River Watershed Landuse Distribution

Station ID Stream NameArea (ha)

Urban (%)

Forest (%)

Agr (%)

SSURGO K-factor

Slope (%)

Elevation (meters)

Score Date

2-BUF026.43 Buffalo River 9,263 4% 84% 12% 0.292 16.50 208.5 56.90 Nov-11 45e/66a James

2DFSP000.30 Fishpond Creek 3,601 3% 80% 17% 0.359 10.10 196.79 78.41 Sep-09 45e James2-BVC003.09 Beaver Creek 4,200 5% 89% 6% 0.322 12.24 198.78 73.11 Oct-07 45e/64c James2-RED003.65 Reed Creek 4,229 4% 71% 26% 0.266 10.85 385.2 61.60 May-11 45e/66a James2-BNF003.52 N.F. Buffalo River 3,633 1% 99% 0% 0.273 25.95 909.3 82.74 Nov-10 66a James2-WIC000.40 Wreck Island Creek 15,047 5% 59% 35% 0.270 9.00 210.63 73.53 Sep-00 45e James2-HAZ006.34 Harris Creek 11,002 10% 69% 21% 0.312 11.07 300.2 73.18 Oct-01 45e/66a James4AFSF004.02 SF Falling River 9,810 5% 66% 29% 0.292 8.16 237.6 62.40 Oct-05 45e Roanoke

- Impaired watershed - Closest matches

Potential TMDL Reference Watersheds

Non-Forested Latest SCISubEco Region

River Basin

Impaired Watershed

Based on the above comparisons, Fishpond Creek was selected as the most

appropriate reference watershed with the greatest similarity of land use distribution and

other sediment generating characteristics with both of the impaired watersheds.

4.2. TMDL Modeling Target Loads

The reference watershed approach for these TMDLs used the sediment load

from the non-impaired Fishpond Creek watershed, area-adjusted to each impaired

watershed, as the TMDL sediment load endpoints for Long Branch and Buffalo River.

Reductions from various sources are specified in the alternative TMDL scenarios that

will achieve the TMDL target within each of the impaired watersheds.

Although sediment is used as a surrogate for benthic health in the development

of these TMDLs, attainment of a healthy benthic community will ultimately be based on


26

biological monitoring of the benthic macro-invertebrate community, in accordance with

established DEQ protocols. If a future review should find that the reductions called for in

these TMDLs based on current modeling are found to be insufficiently protective of local

water quality, then revision(s) will be made as necessary to provide reasonable

assurance that water quality goals will be achieved.


27

Chapter 5: MODELING PROCESS FOR DEVELOPMENT OF THE TMDL

A key component in developing a TMDL is establishing the relationship between

pollutant loadings (both point and nonpoint) and in-stream water quality conditions.

Once this relationship is developed, management options for reducing pollutant loadings

to streams can be assessed. In developing a TMDL, it is critical to understand the

processes that affect the fate and transport of the pollutant that caused the impairment.

Pollutant transport to water bodies is evaluated using a variety of tools, including

watershed modeling. The modeling process, input data requirements, and TMDL load

calculation procedures used in developing the Long Branch and Buffalo River sediment

TMDLs are discussed in this chapter.

5.1. Model Selection

The model selected for development of the sediment TMDL in each of the

impaired watersheds was the Generalized Watershed Loading Functions (GWLF)

model, originally developed by Haith et al. (1992), with modifications by Evans et al.

(2001), Yagow et al. (2002), and Yagow and Hession (2007). The model was run in

metric units and converted to English units for this report.

The loading functions upon which the GWLF model is based are compromises

between the empiricism of export coefficients and the complexity of process-based

simulation models. GWLF is a continuous simulation spatially-lumped parameter model

that operates on a daily time step. The model estimates runoff, sediment, and dissolved

and attached nitrogen and phosphorus loads delivered to streams from complex

watersheds with a combination of point and non-point sources of pollution. The model

considers flow inputs from both surface runoff and groundwater. The hydrology in the

model is simulated with a daily water balance procedure that considers different types of

storages within the system. Runoff is generated based on the Soil Conservation

Service’s Curve Number method as presented in Technical Release 55 (SCS, 1986).


28

GWLF uses three input files for weather, transport, and nutrient data. The

weather file contains daily temperature and precipitation for the period of simulation.

The transport file contains input data primarily related to hydrology and sediment

transport, while the nutrient file contains primarily nutrient values for the various land

uses, point sources, and septic system types. The Penn State Visual Basic™ version of

GWLF with modifications for use with ArcView was the starting point for additional

modifications (Evans et al., 2001). The following modifications related to sediment were

made to the Penn State version of the GWLF model, as incorporated in their ArcView

interface for the model, AvGWLF v. 3.2:

• Urban sediment buildup was added as a variable input. • Urban sediment washoff from impervious areas was added to total sediment load. • Formulas for calculating monthly sediment yield by land use were corrected. • Mean channel depth was added as a variable to the streambank erosion calculation.

The current Virginia Tech (VT) modified version of GWLF (Yagow and Hession,

2007) was used in this study. The VT version includes a correction to the flow

accumulation calculation in the channel erosion routine that was implemented in

December 2005 (VADEQ, 2005). This version also includes modifications from

Schneiderman et al. (2002) to include an unsaturated zone leakage coefficient, and to

add in missing bounds for the calculation of erosivity using Richardson equations which

were intended to have minimum and maximum bounds on daily calculations. These

minimum and maximum bounds were not included in GWLF 2.0, and have been added

to keep calculations within physically expected bounds.

Erosion is generated using a modification of the Universal Soil Loss Equation.

Sediment supply uses a delivery ratio together with the erosion estimates, and sediment

transport takes into consideration the transport capacity of the runoff. Stream bank and

channel erosion was calculated using an algorithm by Evans et al. (2003) as

incorporated in the AVGWLF version (Evans et al., 2001) of the GWLF model and

corrected for a flow accumulation coding error (VADEQ, 2005).


29

5.2. GWLF Model Development for Sediment

Model development for both the reference and impaired watersheds was

performed by assessing the sources of sediment in the watershed, evaluating the

necessary parameters for modeling loads, and applying the model and procedures for

calculating loads.

Buffalo River was simulated as four nested sub-watersheds in order to better

simulate the distribution of land uses and sediment sources in the overall watershed.

The impaired segments and sub-watersheds in Long Branch and Buffalo River are

shown in Figure 5-1.

Figure 5-1. Buffalo River sub-watersheds and impaired segments


30

5.3. Input Data Requirements

5.3.1. Climate Data

Climate in Buffalo Creek watershed was characterized by meteorological

observations from the National Weather Service Cooperative Station 446593 at Pedlar

Dam. Data from Station 448600 at Tye River 1 SE were used to patch missing data. The

period of record used for TMDL modeling was a nineteen-year period from January

1992 through December 2010, with the preceding 9 months of data used to initialize

storage parameters.

5.3.2. Existing Land Use

Modeled land uses for the Buffalo River watersheds were derived from the USDA

National Agricultural Statistics Service digital cropland data layer for 2009, as discussed

in Section 2.5. Attendees at the June 14, 2012 Technical Advisory Committee meeting

in Amherst County noted that the Cropland acreage indicated from the NASS cropland

data layer was significantly low. After a close examination of the aerial imagery of

Buffalo River this acreage was adjusted so that approximately 50% of the land use

designated as Other Pastures/Hay was changed to Row Crop. The revised acreages of

NASS categories were then consolidated into general land use categories of Row Crop,

Hay, Pasture, Forest, and various “developed urban” categories, as shown in Table 5-1.

Table 5-1. NASS Land Use Group Distributions

Row Crop Hay Pasture Forest BarrenUrban open

space LDI MDI HDI Water Total

Buffalo River - lower BUF1 108.7 319.7 996.7 6,002.9 0.4 301.4 21.3 0.7 0.0 3.0 7,754.8Buffalo River - middle BUF2 26.6 194.8 442.7 2,649.2 0.0 166.9 30.9 2.1 0.6 0.0 3,513.8Buffalo River - upper BUF3 5.9 29.6 397.5 9,242.2 1.6 403.1 16.2 0.0 0.0 0.0 10,096.0Long Branch LOB 1.8 37.0 245.6 1,204.5 0.0 32.6 3.3 0.3 0.0 0.4 1,525.6Fishpond Creek FSP 51.2 888.0 561.8 7,126.1 1.0 260.7 5.4 0.0 0.0 7.0 8,901.3Fishpond Creek adjusted for LOB FSPadjLOB 8.8 152.2 96.3 1,221.4 0.2 44.7 0.9 0.0 0.0 1.2 1,525.6Fishpond Creek adjusted for BUF FSPadjBUF 131.8 2,283.6 1,444.7 18,325.1 2.6 670.4 13.9 0.0 0.0 17.9 22,890.1

Simulated WatershedWatershed

Code Area in acres

LDI = low intensity developed; MDI = medium intensity developed; HDI = high intensity developed

The Row Crop category was subdivided into hi-till and low-till cropland based on

estimates by local conservation agency personnel as 40% hi-till and 60% low-till. The

Hay and Pasture acreages were combined and reassigned based on local estimates of

23% hay and 77% pasture. For both Buffalo River and Fishpond Creek watersheds, the


31

area in “riparian pasture” was assigned as the pasture area lying within a 35-foot

buffered area around perennial streams in each watershed. One “animal feeding

operation” was included in the lower Buffalo River watershed, based on the inventory

conducted as part of the bacteria TMDL on the Tye River (Kline et al., 2013). The areas

in “riparian pasture” were subtracted from the Pasture area in each watershed. The

remaining Pasture area was sub-divided into 10% “good”, 70% “fair”, and 20% “poor”

pasture land uses, as assessed by local conservation agency personnel. A “harvested

forest” land use was created as 1% of the Forest category, similar to procedures used in

the CBWM (USEPA, 2010). The “barren” category was re-assessed as 2% of all the

developed land use categories for Buffalo River, and subtracted from the “Urban Open

Space” land use. The “developed” categories were sub-divided into pervious and

impervious portions, with “urban open space” assigned to the pervious portion of the

“low intensity developed” land use. Impervious percentages of 20%, 50%, and 80%

were used, respectively, for the low intensity, medium intensity and high intensity

developed areas. The simulated land uses and their derivations are summarized in

Table 5-2.

Each land use within a sub-watershed formed a hydrologic response unit (HRU).

Model parameters were then calculated for each HRU using GIS analysis to reflect the

variability in topographic and soil characteristics across the watershed.


32

Table 5-2. Modeled Land Use Categories

NASS Land Uses NASS Groups % Impervious Modeled Land Use Categories

Hi-till croplandLo-till cropland

Alfalfa, other hays Hay 0 HayGood pastureFair pasturePoor PastureRiparian pastureAnimal feeding operationForestHarvested forest

Barren Barren 0 BarrenUrban open space Open Space 0 Pervious LDI

20 Impervious LDIPervious LDI

50 Impervious MDIPervious MDI

80 Impervious HDIPervious HDI

Row Crop

Pasture

Forest

LDI

0

0

0Deciduous forest, evergreen forest, mixed forest,

Corn, sorghum, soybeans, winter wheat, etc.

Developed, low intensity

Developed, medium intensity

Developed, high intensity

Pasture/grass, shrubland, grassland herbaceous

MDI

HDI

5.4. Future Land Use

The Amherst County Comprehensive Plan adopted in 2007 shows the impaired

watersheds within the “Agricultural Limited” and “Public” areas of the County. Future

residential development is expected to be minimal. As no major changes are envisioned

for the watersheds, future land use in the watershed was represented as the existing

conditions. Detailed land use distributions for Existing conditions in both Buffalo River

and the area-adjusted Fishpond Creek watersheds, are given below in Table 5-3.


33

Table 5-3. Existing Land Use Distributions

HiTill Rowcrop (hit) 23.2 0.3 15.4 1.0LoTill Rowcrop (lot) 34.7 0.4 37.9 2.5Pasture (pas_g) 78.5 8.3 375.1 25.0Pasture (pas_f) 549.4 58.1 515.7 34.4Pasture (pas_p) 157.0 16.6 46.9 3.1Riparian pasture (trp) 41.4 4.9 18.7 1.2AFO (afo) 2.4 0.0 5.2 0.3Hay (hay) 249.3 26.4 547.2 36.5Forest (for) 7,651.8 482.6 7,341.9 489.3Harvested forest (hvf) 77.3 4.9 74.2 4.9Transitional (barren) 7.9 0.3 5.6 0.4Pervious Low Intensity Developed (pur_LDI) 381.9 14.0 271.3 18.1Pervious Med Intensity Developed (pur_MDI) 0.6 0.1 0.0 0.0Pervious High Intensity Developed (pur_HDI) 0.0 0.0 0.0 0.0Impervious LDI (imp_LDI) 5.8 0.3 1.1 0.1Impervious MDI (imp_MDI) 0.6 0.1 0.0 0.0Impervious HDI (imp_HDI) 0.2 0.0 0.0 0.0Total Simulated Area 9,262.1 617.2 9,256.2 616.9Water 1.4 0.2 7.3 0.5Total Area 9,263.5 617.4 9,263.5 617.4

Modeled Land Use Categories Buffalo River

Long Branch

Fishpond Creek - area adjusted (Buffalo River)

Fishpond Creek - area adjusted (Long Branch)

(area in acres)

5.5. GWLF Parameter Evaluation

All parameters were evaluated in a consistent manner for both watersheds in

order to ensure their comparability. All GWLF parameter values were evaluated using a

combination of GWLF user manual guidance (Haith et al., 1992), AVGWLF procedures

(Evans et al., 2001), procedures developed during the 2006 statewide NPS pollution

assessment (Yagow and Hession, 2007), and best professional judgment.

Hydrologic and sediment parameters are all included in GWLF’s transport input

file, with the exception of urban sediment buildup rates, which are in the nutrient input

file. Descriptions of each of the hydrologic and sediment parameters are listed below

according to whether the parameters were related to the overall watershed, to the month

of the year, or to individual land uses. The GWLF parameter values used for both the

Buffalo River and Fishpond Creek watersheds are detailed in Appendix B.


34

5.5.1. Hydrology Parameters Watershed-Related Parameter Descriptions

• Unsaturated Soil Moisture Capacity (SMC, cm): The amount of moisture in the root zone, evaluated as a function of the area-weighted soil type attribute - available water capacity.

• Recession coefficient (day-1): The recession coefficient is a measure of the rate at which streamflow recedes following the cessation of a storm, and is approximated by averaging the ratios of streamflow on any given day to that on the following day during a wide range of weather conditions, all during the recession limb of each storm’s hydrograph. This parameter was evaluated using the following relationship from Lee et al. (2000): RecCoeff = 0.045+1.13/(0.306+Area in square kilometers)

• Seepage coefficient: The seepage coefficient represents the fraction of flow lost as seepage to deep storage.

• Leakage coefficient: The leakage coefficient represents the fraction of infiltration that bypasses the unsaturated zone through macro-pore flow. An increase in this coefficient, initially set to zero, decreases ET losses and increases baseflow.

The following parameters were initialized by running the model for a 9-month period prior to the period used for load calculation:

• Initial unsaturated storage (cm): Initial depth of water stored in the unsaturated (surface) zone.

• Initial saturated storage (cm): Initial depth of water stored in the saturated zone. • Initial snow (cm): Initial amount of snow on the ground at the beginning of the

simulation. • Antecedent Rainfall for each of 5 previous days (cm): The amount of rainfall on

each of the five days preceding the current day. Month-Related Parameter Descriptions

• Month: Months were ordered, starting with April and ending with March – in keeping with the design of the GWLF model.

• ET_CV: Composite evapotranspiration cover coefficient, calculated as an area-weighted average from land uses within each watershed.

• Hours per Day: Mean number of daylight hours. • Erosion Coefficient: This is a regional coefficient used in Richardson’s equation

for calculating daily rainfall erosivity. Each region is assigned separate coefficients for the months October-March, and for April-September.

Land Use-Related Parameter Descriptions

• Curve Number: The SCS curve number (CN) is used in calculating runoff associated with a daily rainfall event, evaluated using SCS TR-55 guidance.


35

5.5.2. Sediment Parameters Watershed-Related Parameter Descriptions

• Sediment delivery ratio: The fraction of erosion – detached sediment – that is transported or delivered to the edge of the stream, calculated as an inverse function of watershed size (Evans et al., 2001).

Land Use-Related Parameter Descriptions

• USLE K-factor: The soil erodibility factor was calculated as an area-weighted average of all component soil types.

• USLE LS-factor: This factor is calculated from slope and slope length measurements by land use. Slope is evaluated by GIS analysis, and slope length is calculated as an inverse function of slope.

• USLE C-factor: The vegetative cover factor for each land use was evaluated following GWLF manual guidance, Wischmeier and Smith (1978), and Hession et al. (1997); and then adjusted after consultation with local NRCS personnel.

• Daily sediment buildup rate on impervious surfaces: The daily amount of dry deposition deposited from the air on impervious surfaces on days without rainfall, assigned using GWLF manual guidance.

Streambank Erosion Parameter Descriptions (Evans et al., 2003)

• % Developed land: percentage of the watershed with urban-related land uses – defined as all land in MDI and HDI land uses, as well as the impervious portions of LDI.

• Animal density: calculated as the number of beef and dairy 1000-lb equivalent animal units (AU) divided by the watershed area in acres.

• Curve Number: area-weighted average value for the watershed. • K Factor: area-weighted USLE soil erodibility factor for the watershed. • Slope: mean percent slope for the watershed. • Stream length: calculated as the total stream length of natural perennial stream

channels, in meters. Excludes any non-erosive hardened and piped sections of the stream.

• Mean channel depth (m): calculated from relationships developed either by the Chesapeake Bay Program or by USDA-NRCS by physiographic region, of the general form – y = a * Ab, where y = mean channel depth in ft, and A = drainage area in square miles (USDA-NRCS, 2005).

5.6. Supplemental Post-Model Processing

After modeling was performed on individual and cumulative sub-watersheds,

model output was post-processed in a Microsoft Excel™ spreadsheet to summarize the

modeling results and to account for existing levels of BMPs already implemented within

each watershed.


36

Sediment BMPs are required on harvested forest lands and on disturbed lands

subject to Erosion and Sediment (E&S) regulations. The harvested forest land use areas

were simulated as if they had BMPs performing at 50% of their potential efficiency, while

the disturbed lands were simulated without BMPs. Potential sediment reduction

efficiencies for both types of BMPs were obtained from the Chesapeake Bay Watershed

Model for the Piedmont Crystalline Non-tidal region (USEPA, 2010), where maximum

sediment reduction efficiencies of 60% are expected from harvested forest land and

40% reductions from construction areas. For the allocation scenarios, loads from both of

these land uses were simulated as operating at their respective full potential

efficiencies.

The extent and effect of existing agricultural BMPs in both the Buffalo River and

the reference Fishpond Creek watersheds were based on spatial data provided by

Virginia’s Department of Conservation and Recreation from their Agricultural BMP Cost-

Share Database for the JM28 and JA03 sixth-order watersheds, respectively. The data

included cost-shared BMPs installed from 1998 through August 2012. During that time,

no BMPs were cost-shared within the Fishpond Creek watershed, while 7 BMPs had

been cost-shared in the Buffalo River watershed.

Load reductions and corresponding pass-through fractions of the sediment load

from each land use were calculated based on BMP efficiencies and credits for upland

filtering by buffers, as used in the Chesapeake Bay Watershed Model (USEPA, 2010).

Modeled sediment loads within each land use category were then multiplied by their

respective pass-through fractions to simulate the reduced loads resulting from existing

BMPs. One BMP in the middle Buffalo River watershed was represented as a land use

change from cropland to forest.

5.7. Representation of Sediment Sources

Sediment is generated in the Buffalo River and Fishpond Creek watersheds

through the processes of surface runoff, in-channel disturbances, and streambank and

channel erosion, as well as from natural background contributions and permitted

sources. Sediment generation is accelerated through human-induced land-disturbing


37

activities related to a variety of agricultural, forestry, mining, transportation, and

residential land uses.

Permitted sediment dischargers in the Buffalo River watershed include both

stormwater and general permit facilities. Stormwater discharges include urban

stormwater runoff from MS4, municipal, and industrial permits, while construction

permits regulated through Virginia’s Erosion and Sediment Control Program and single-

family household alternative onsite wastewater disposal systems fall under broader

aggregate General Permits.

5.7.1. Surface Runoff

During runoff events, sediment loading occurs from both pervious and impervious

surfaces around the watershed. For pervious areas, soil is detached by rainfall impact or

shear stresses created by overland flow and transported by overland flow to nearby

streams. This process is influenced by vegetative cover, soil erodibility, slope, slope

length, rainfall intensity and duration, and land management practices. During periods

without rainfall, dirt, dust and fine sediment build up on impervious areas through dry

deposition, which is then subject to washoff during rainfall events. Pervious area

sediment loads were modeled using a modified USLE erosion detachment algorithm,

monthly transport capacity calculations, and a sediment delivery ratio in the GWLF

model to calculate loads at the watershed outlet. Impervious area sediment loads were

modeled in the GWLF model using an exponential buildup-washoff algorithm.

5.7.2. Channel and Streambank Erosion

Streambank erosion was modeled within the GWLF model using a modification of

the routine included in the AVGWLF version of the GWLF model (Evans et al., 2001).

This routine calculates average annual streambank erosion as a function of percent

developed land, average area-weighted curve number (CN) and K-factors, watershed

animal density, average slope, streamflow volume, mean channel depth, and total

stream length in the watershed. Livestock population, which figures into animal density,

was estimated based on a stocking density of 4.5 acres of available pasture per animal

unit (1 animal unit = 1,000 lbs of live weight).


38

5.7.3. Industrial Stormwater

Currently, there are no active Industrial Storm Water General Permits (ISWGPs)

in the Long Branch watershed and two active ISWGPs in the Buffalo River watershed.

Current loads for each facility were simulated as part of the urban pervious and

impervious land use categories. Permitted WLA loads for each facility were calculated

as the permitted area of the facility times the permitted average TSS concentration of

100 mg/L times the average annual runoff (simulated for low intensity developed areas),

as shown in Table 5-4.

Table 5-4. Industrial Stormwater General Permit (ISWGP) WLA Loads

Facility NameVPDES Permit

NumberSource Type Receiving Stream Area

(acres)

Permitted Average TSS Concentration

(mg/L)

Average Annual Runoff (in/yr)

TSS WLA (tons/yr)

E F Fitzgerald Lumber VAR050404 ISWGP South Fork Buffalo 8 100 35.79 3.24Ellington Wood Products Inc VAR050411 ISWGP Buffalo River 3 100 35.79 1.22 Load = X acres * Y mg/L * Z in/yr * 0.000113317 tons/yr

5.7.4. Construction Stormwater

Since there were no active land disturbing (construction stormwater) permits in

the Long Branch or Buffalo River watersheds when this TMDL was developed, an

estimate was made to represent a long term average condition. In conjunction with the

local Technical Advisory Committee, it was estimated that 2% of the developed acreage

should be allotted for such permits in any given year. Existing TSS loads from

construction sites (“barren” land uses) were simulated as having no current BMPs.

5.7.5. Other Permitted Sources (VPDES and General Permits) There are no general discharge permits for single-family homes and no VPDES

permits in the Buffalo River watersheds.

5.8. Accounting for Critical Conditions and Seasonal Variations

5.8.1. Selection of Representative Modeling Period

Selection of the modeling period was based on the availability of daily weather

data and the need to represent variability in weather patterns over time in the

watershed. A long period of weather inputs was selected to represent long-term


39

variability in the watershed. The model was run using a weather time series from April

1991 through December 2010, with the first 9 months used as an initialization period for

internal storages within the model. The remaining 19-year period was used to calculate

average annual sediment loads in all watersheds.

5.8.2. Critical Conditions

The GWLF model is a continuous simulation model that uses daily time steps for

weather data and water balance calculations. The period of rainfall selected for

modeling was chosen as a multi-year period that was representative of typical weather

conditions for the area, and included “dry”, “normal” and “wet” years. The model,

therefore, incorporated the variable inputs needed to represent critical conditions during

low flow – generally associated with point source loads – and critical conditions during

high flow – generally associated with nonpoint source loads.

5.8.3. Seasonal Variability

The GWLF model used for this analysis considered seasonal variation through a

number of mechanisms. Daily time steps were used for weather data and water balance

calculations. The model also used monthly-variable parameter inputs for evapo-

transpiration cover coefficients, daylight hours/day, and rainfall erosivity coefficients for

user-specified growing season months.

5.9. Existing and Future Sediment Loads

Sediment loads were simulated for all individual land uses with the GWLF model

in the Long Branch, Buffalo River, and the reference Fishpond Creek watersheds for

Existing conditions. Sediment loads for permitted sources and projected future loads for

construction were calculated for the Long Branch and Buffalo River watersheds. These

loads were then subtracted from the appropriate barren and developed land use

categories in the Long Branch and Buffalo River watersheds for the Future scenario.

Table 5-5 includes sediment loads by land use from Future conditions for the Long

Branch and Buffalo River watersheds and the existing loads for the reference

watershed, Fishpond Creek, area-adjusted separately to each impaired watershed.


40

Table 5-5. Future Sediment Loads in the TMDL Watersheds and Existing Sediment Loads in the Reference Watershed

BUF LOB FSPadjBUF FSPadjLOBBuffalo River

Long Branch

Fishpond Creek - adjusted to BUF

Fishpond Creek - adjusted to LOB

Sediment Load (tons/yr)HiTill Rowcrop (hit) 83.7 13.4 188.9 20.4LoTill Rowcrop (lot) 26.3 4.2 97.1 10.5Pasture (pas_g) 43.0 7.2 215.1 23.2Pasture (pas_f) 1,382.2 234.4 1,362.0 146.9Pasture (pas_p) 753.4 130.4 240.7 26.0Riparian pasture (trp) 2,005.1 388.5 992.2 106.9AFO (afo) 0.0 0.0 0.0 0.0Hay (hay) 271.8 71.9 807.8 87.1Forest (for) 1,261.3 108.8 692.0 74.6Harvested forest (hvf) 101.0 8.6 54.3 5.8Transitional (barren) 446.0 26.8 185.3 20.0Pervious LDI (pur_LDI) 234.5 14.2 121.0 13.0Pervious MDI (pur_MDI) 0.3 0.1 0.0 0.0Pervious HDI (pur_HDI) 0.0 0.0 0.0 0.0Impervious LDI (imp_LDI) 3.4 0.2 0.7 0.0Impervious MDI (imp_MDI) 0.9 0.1 0.0 0.0Impervious HDI (imp_HDI) 0.1 0.0 0.0 0.0Channel Erosion 122.1 0.9 190.9 1.0Permitted Sources 306.4 16.2 0.0 0.0Total Sediment Load 7,041.6 1,025.9 5,147.9 535.4

Land Use/Source Categories

Future Existing


41

Chapter 6: TMDLS AND ALLOCATIONS

The objective of a TMDL is to allocate allowable loads among different pollutant

sources so that appropriate actions can be taken to achieve water quality standards

(USEPA, 1991). The stressor analyses in the Long Branch and Buffalo River

watersheds indicated that sediment was the “most probable stressor”, and therefore,

sediment will serve as the basis for development of these TMDLs. The reference

watershed approach was used to set appropriate sediment TMDL load endpoints for

each impaired segment and their associated watersheds.

6.1. Long Branch and Buffalo River Sediment TMDLs

6.1.1. TMDL Components The sediment TMDLs for the Long Branch and Buffalo River watersheds were

calculated using the following equation:

TMDL = ∑WLA + ∑LA + MOS

where ∑WLA = sum of the wasteload (permitted) allocations;

∑LA = sum of load (nonpoint source) allocations; and

MOS = margin of safety.

The sediment TMDL load for each TMDL watershed was defined as the average

annual sediment load from the Fishpond Creek watershed, area-adjusted to each

impaired watershed.

6.1.1.1. Waste Load Allocation The waste load allocation (WLA) is comprised of sediment loads from aggregates

of both general permits and construction permits. No additional Future Growth WLA was

included. However, the simulated future condition was included as a percentage of

developed acreage rather than the current permitted acreage.


42

The WLA for the industrial stormwater permitted sources were calculated from

the area of the facility, the permitted average TSS concentration, and the maximum

simulated annual runoff for the facilities, as shown in Table 5-4.

Aggregated construction WLA loads for each sub-watershed were simulated as

the reserved construction permit area times the unit-area simulated sediment load for

the “barren” land use time a 40% reduction efficiency, as shown in Table 6-1.

Table 6-1. Aggregated Construction WLA Loads

The WLAs were developed in the absence of erosion and sediment control BMPs on site, while installation of BMPs in compliance with an approved Storm Water Pollution Prevention Plan is presumed to meet the assigned WLAs.

6.1.1.2. Margin of Safety A margin of safety (MOS) is factored into a TMDL to account for model

uncertainty. The MOS can be either explicit, as an additional load reduction

requirement, or implicit, which incorporates conservative assumptions within the

application of the TMDL model. An explicit MOS was used in this sediment TMDL. An

explicit 10% MOS was used in the TMDL calculation based on best professional

judgment and the precedence of other TMDLs developed using the reference watershed

approach for biological impairments due to sediment in Virginia. A MOS of 53.5 tons/yr

is included in the Long Branch sediment TMDL and a MOS of 514.8 tons/yr is included

in the Buffalo River sediment TMDL.

6.1.1.3. Load Allocation The load allocation (LA) represents the contributions from nonpoint sources. The

LA was calculated as the TMDL minus the sum of WLA and MOS. The TMDL load and

its components for each TMDL watershed are shown in Table 6-2.


43

Table 6-2. Long Branch and Buffalo River Sediment TMDLs

Long Branch: VAC-H11R_LOB01A04; Cause Group Code H11R-01-BENTMDL LA MOS

535.4 465.7 53.5construction aggregate WLA 16.2 tons/yr

Buffalo River: VAC-H11R_BUF04A08; Cause Group Code H11R-02-BENTMDL LA MOS

5,147.9 4,326.7 514.8construction aggregate WLA 302.6 tons/yrgeneral permits aggregate WLA 3.8 tons/yr

WLA(tons/yr)

306.4

WLA

16.2(tons/yr)

6.1.2. Maximum Daily Loads The USEPA (2006a) has mandated that TMDL studies submitted since 2007

include a maximum “daily” load (MDL), in addition to the average annual loads shown in

Section 6.2.1. The approach used to develop these MDLs was provided in Appendix B

of a related USEPA guidance document (USEPA, 2006b). The appendix to this USEPA

document, entitled “Approaches for developing a Daily Load Expression for TMDLs

computed for Longer Term Averages” is dated December 15, 2006. This guidance

provides a procedure for calculating an MDL (tons/day) from the long-term average

(LTA) annual TMDL load (tons/yr) and a coefficient of variation (CV) based on annual

loads over a period of time. The “LTA to MDL multipliers” for Long Branch and Buffalo

River were calculated from the 1992-2010 simulated output of annual sediment loads

using the GWLF model.

Annual simulated sediment loads for Long Branch watershed ranged from 138 to

1,818 t/yr, producing a coefficient of variation (CV) = 0.5126. The “LTA to MDL”

multiplier was then interpolated from the USEPA guidance and calculated as 3.436. The

MDL was calculated as the TMDL divided by 365 days/yr and multiplied by 3.436.

Annual simulated sediment loads for Buffalo River watershed ranged from 1,056

to 12,100 t/yr, producing a coefficient of variation (CV) = 0.5029. The “LTA to MDL”

multiplier was then interpolated from the USEPA guidance and calculated as 3.374. The

MDL was calculated as the TMDL divided by 365 days/yr and multiplied by 3.374.


44

Since the WLA represents permitted loads, no multiplier was applied to these

loads. Therefore the daily WLA and components were converted to daily loads by

dividing by 365 days/yr. The daily LA was calculated as the MDL minus the daily WLA

minus the daily MOS. The resulting sediment MDLs and associated components for the

impaired Long Branch and Buffalo River stream segments are shown in Table 6-3 in

units of tons/day.

Expressing the TMDL as a daily load does not interfere with a permit writer’s

authority under the regulations to translate that daily load into the appropriate permit

limitation, which in turn could be expressed as an hourly, weekly, monthly or other

measure (USEPA, 2006a).

Table 6-3. Long Branch and Buffalo River Maximum “Daily” Sediment Loads

Long Branch: VAC-H11R_LOB01A04; Cause Group Code H11R-01-BENMDL LA MOS

5.04 4.50 0.50construction aggregate WLA 0.044 tons/day

Buffalo River: VAC-H11R_BUF04A08; Cause Group Code H11R-02-BENMDL LA MOS

47.58 41.99 4.75construction aggregate WLA 0.829 tons/daygeneral permits aggregate WLA 0.01 tons/day

WLA(tons/day)

0.839

WLA

0.044(tons/day)

6.2. Allocation Scenarios

The target allocation sediment load for each watershed allocation scenario is the

TMDL minus the MOS. Allocation scenarios were created by applying percent

reductions to the various land use/source categories until the target allocation load was

achieved for the Long Branch and Buffalo River watersheds.

Two allocation scenarios were created for each watershed and reviewed by local

stakeholders (Table 6-4 and Table 6-5). Harvested Forest BMPs are typically required

for all commercially harvested areas, but are not always implemented in small-lot

harvests. In the Future load, these BMPs were represented as being partially (30%)

effective, while for both allocation scenarios, these BMPs were simulated as being 60%

effective (efficiency used in the Chesapeake Bay Watershed Model; USEPA, 2010).


45

Scenario 1 applies equal percent reductions from all land uses and sources, except

forest, harvested forest, and point sources. Scenario 2 applies equal percent reductions

from the largest source (pasture) and the “developed” land use, along with the

harvested forest BMPs. The preferred scenario used for sediment reduction for each

watershed will be determined during TMDL implementation planning.

The amount of reductions required in the Buffalo River watershed was reduced

by the amount of load reduction from BMPs to be implemented for the allocation

scenario in Long Branch, and multiplied by a factor to account for differences in the

sediment delivery ratio between the two watersheds.

Table 6-4. Sediment TMDL Load Allocation Scenario, Long Branch

Reduction

Load

Reduction

Load

Row Crops 17.6 59.8% 7.1 17.6Pasture 760.6 59.8% 305.6 66.7% 253.2Hay 71.9 59.8% 28.9 71.9Forest 108.8 108.8 108.8Harvested Forest 8.6 42.9% 4.9 42.9% 4.9Developed 25.1 59.8% 10.1 66.7% 8.4Channel Erosion 0.9 59.8% 0.4 0.9Permitted WLA 16.2 16.2 16.2Total Load 1,009.7 481.9 481.9Target Allocation Load = 481.9% Reduction Needed = 52.3%

Scenario 1 Scenario 2Land Use/ Source

Group


(tons/yr)


46

Table 6-5. Sediment TMDL Load Allocation Scenario, Buffalo River

% Reduction

Allocated Load

% Reduction

Allocated Load

Row Crops 110.0 34.2% 72.4 110.0Pasture 4,183.7 34.2% 2,753.1 38.0% 2,595.0Hay 271.8 34.2% 178.9 271.8Forest 1,261.3 1,261.3 1,261.3Harvested Forest 101.0 42.9% 57.7 42.9% 57.7Developed 378.8 34.2% 249.2 38.0% 234.9Channel Erosion 122.1 34.2% 80.4 122.1Permitted WLA 306.4 306.4 306.4Total Load 6,735.2 4,959.4 4,959.4Target Allocation Load = 4,633.1Long Branch Reduction = 326.3Revised Allocation Load = 4,959.4% Reduction Needed = 26.4%

Scenario 1 Scenario 2Land Use/ Source Group


(tons/yr)


47

Chapter 7: TMDL IMPLEMENTATION

The goal of the TMDL program is to establish a three-step path that will lead to

attainment of water quality standards. The first step in the process is to develop TMDLs

that will result in meeting water quality standards. This report represents the culmination

of that effort for the benthic impairments on Long Branch and Buffalo River. The second

step is to develop a TMDL Implementation Plan. The final step is to implement the

TMDL Implementation Plan and to monitor stream water quality to determine if water

quality standards are being attained.

Once a TMDL has been approved by USEPA and then the State Water Control

Board (SWCB), measures must be taken to reduce pollutant levels in the stream. These

measures, which can include the use of better treatment technology and the installation

of BMPs, are implemented in an iterative process that is described along with specific

BMPs in the Implementation Plan. The process for developing an Implementation Plan

has been described in the “TMDL Implementation Plan Guidance Manual”, published in

July 2003 and available upon request from the DEQ and DCR TMDL project staff or at

http://www.deq.virginia.gov/Portals/0/DEQ/Water/TMDL/ImplementationPlans/ipguide.p

df. With successful completion of Implementation Plans, Virginia begins the process of

restoring impaired waters and enhancing the value of this important resource.

Additionally, development of an approved Implementation Plan will improve a locality's

chances for obtaining financial and technical assistance during implementation.

Watershed stakeholders will have opportunity to participate in the development of

the TMDL Implementation Plan, which is the next step in the TMDL process. Specific

goals for BMP implementation will be established as part of the Implementation Plan

development. DCR and DEQ will work closely with watershed stakeholders, interested

state agencies, and support groups to develop an acceptable Implementation Plan that

will result in meeting the water quality target in each impaired stream segment. Stream

delisting of the Long Branch and Buffalo River impaired stream segments will be based

on biological health and not on numerical pollution loads.

http://www.deq.virginia.gov/Portals/0/DEQ/Water/TMDL/ImplementationPlans/ipguide.pdf

http://www.deq.virginia.gov/Portals/0/DEQ/Water/TMDL/ImplementationPlans/ipguide.pdf


48

7.1. Link to ongoing Restoration Efforts

Implementation of BMPs to address the benthic impairments in Long Branch and

Buffalo River will be coordinated with BMPs required to meet bacteria water quality

standards in the TMDL concurrently being developed for the encompassing portion of

the Buffalo River watershed.

7.2. Reasonable Assurance for Implementation

7.2.1. TMDL Monitoring

DEQ will monitor benthic macro-invertebrates and habitat in accordance with its

biological monitoring program at station 2-LOB000.37 on Long Branch and station 2-

BUF026.43 on Buffalo River. DEQ will continue to use data from these monitoring

stations to evaluate improvements in the benthic community and the effectiveness of

TMDL implementation in attainment of the general water quality standard.

7.2.2. Regulatory Framework

7.2.2.1 Federal Regulations

While section 303(d) of the Clean Water Act and current USEPA regulations do

not require the development of TMDL implementation plans as part of the TMDL

process, they do require reasonable assurance that the load and wasteload allocations

can and will be implemented. Federal regulations also require that all new or revised

National Pollutant Discharge Elimination System (NPDES) permits must be consistent

with the assumptions and requirements of any applicable TMDL WLA (40 CFR §122.44

(d)(1)(vii)(B)). All such permits should be submitted to USEPA for review.

7.2.2.2 State Regulations

Additionally, Virginia’s 1997 Water Quality Monitoring, Information and

Restoration Act (WQMIRA) directs the State Water Control Board to “develop and

implement a plan to achieve fully supporting status for impaired waters” (Section 62.1-

44.19.7). WQMIRA also establishes that the implementation plan shall include the date

of expected achievement of water quality objectives, measurable goals, corrective

actions necessary and the associated costs, benefits and environmental impacts of


49

addressing the impairments. USEPA outlines the minimum elements of an approvable

implementation plan in its 1999 “Guidance for Water Quality-Based Decisions: The

TMDL Process.” The listed elements include implementation actions/management

measures, timelines, legal or regulatory controls, time required to attain water quality

standards, monitoring plans and milestones for attaining water quality standards.

For the implementation of the WLA component of each TMDL, the

Commonwealth utilizes the Virginia NPDES program, which typically includes

consideration of the WQMIRA requirements during the permitting process.

Requirements of the permit process should not be duplicated in the TMDL process and

implementation plan development, especially those implemented through water quality

based effluent limitations. However, those requirements that are considered BMPs may

be enhanced by inclusion in the TMDL IP, and their connection to the identified

impairment. New permitted point source discharges will be allowed under the waste load

allocation provided they implement applicable VPDES requirements.

7.2.3. Implementation Funding Sources Implementation funding sources will be determined during the implementation

planning process by the local watershed stakeholder planning group with assistance

from DEQ and DCR. Potential sources of funding include Section 319 funding for

Virginia’s Nonpoint Source Management Program, the U.S. Department of Agriculture’s

Conservation Reserve Enhancement and Environmental Quality Incentive Programs,

the Virginia State Revolving Loan Program, and the Virginia Water Quality Improvement

Fund, although other sources are also available for specific projects and regions of the

state. The TMDL Implementation Plan Guidance Manual contains additional information

on funding sources, as well as government agencies that might support implementation

efforts and suggestions for integrating TMDL implementation with other watershed

planning efforts.

7.2.4. Reasonable Assurance Summary

Watershed stakeholders will have opportunities to provide input and to participate

in the development of the implementation plan, which will also be supported by regional

and local offices of DEQ, DCR, and other cooperating agencies.


50

Once developed, DEQ intends to incorporate the TMDL implementation plan into

the appropriate Water Quality Management Plan (WQMP), in accordance with the Clean

Water Act’s Section 303(e). In response to a Memorandum of Understanding (MOU)

between USEPA and DEQ, DEQ also submitted a draft Continuous Planning Process to

USEPA in which DEQ commits to regularly updating the WQMPs. Thus, the WQMPs

will be, among other things, the repository for all TMDLs and TMDL implementation

plans developed within a river basin.

Taken together, the follow-up monitoring, WQMIRA, public participation, the

Continuing Planning Process, and the reductions called for in the concurrent bacteria

TMDL on the Buffalo River comprise a reasonable assurance that the Long Branch and

Buffalo River sediment TMDLs will be implemented and water quality will be restored.


51

Chapter 8: PUBLIC PARTICIPATION

Public participation was elicited at every stage of the TMDL development in order

to receive inputs from stakeholders and to apprise the stakeholders of the progress

made.

The first Technical Advisory Committee Meeting for all biological and benthic

impairments on the Buffalo River (including Long Branch) was on June 14, 2012 at the

Central Virginia Community College in Amherst, Virginia. The purpose of that meeting

was to introduce agency stakeholders to the TMDL process and to discuss the

impairments identified on stream segments in these watersheds. The meeting was

attended by ten people.

The first Public Meeting was held at the Central Virginia Community College in

Amherst on June 25, 2012, where the TMDL process was introduced, local stream

impairments were presented, and comments were solicited from the stakeholder group.

The first public meeting was attended by ten people.

A second Technical Advisory Committee meeting was held in the form of a

teleconference on September 24, 2012. The results from the stressor analysis were

presented, and comments were solicited from the stakeholder group. Nine people

participated in the conference call.

A third Technical Advisory Committee meeting was held on April 17, 2013 at the

Central Virginia Community College in Amherst to present modeling procedures, draft

modeling results, and to solicit feedback on the proposed TMDL strategy.

A final public meeting was held on April 25, 2013 to present the draft TMDL report

to address both bacteria and benthic impairments on the Buffalo River (including Long

Branch) watersheds. This final TMDL public meeting was attended by 13 stakeholders.

The public comment period ended on June 13, 2013. No comments were received.


52

Chapter 9: REFERENCES Barbour, M. T., J. Gerritsen, B. D. Snyder, and J. B. Stribling. 1999. Rapid bioassessment protocols for

use in streams and wadeable rivers: Periphyton, benthic macro-invertebrates, and fish. Second Edition. EPA 841-B-99-002. U. S. Environmental Protection Agency. Washington, DC.

Clements, W.H. 1994. Benthic invertebrate community responses to heavy metals in the upper Arkansas River Basin, Colorado. J. North Amer. Benth. Soc. 13:30-44.

Evans, B. M., S. A. Sheeder, K. J. Corradini, and W. S. Brown. 2001. AVGWLF version 3.2. Users Guide. Environmental Resources Research Institute, Pennsylvania State University and Pennsylvania Department of Environmental Protection, Bureau of Watershed Conservation.

Evans, B.M., S. A. Sheeder, and D.W. Lehning, 2003. A spatial technique for estimating streambank erosion based on watershed characteristics. J. Spatial Hydrology, Vol. 3, No. 1.

Haith, D. A., R. Mandel, and R. S. Wu. 1992. GWLF. Generalized Watershed Loading Functions, version 2.0. User’s Manual. Department of Agricultural and Biological Engineering, Cornell University. Ithaca, New York.

Hession, W. C., M. McBride, and L. Misiura. 1997. Revised Virginia nonpoint source pollution assessment methodology. A report submitted to the Virginia Department of Conservation and Recreation, Richmond, Virginia. The Academy of Natural Sciences of Philadelphia, Patrick Center for Environmental Research. Philadelphia, Pennsylvania.

Kline, K. et al. 2013. Bacteria Total Maximum Daily Load Development for Mill Creek, Turner Creek, Rutledge Creek, Buffalo River, Piney River, Hat Creek, Rucker Run, and Tye River in Amherst and Nelson Counties, Virginia.

Kline, K., G.Yagow and B. Benham. 2013. Benthic TMDL Development Stressor Analysis Report: Buffalo River and Long Branch, Amherst County, Virginia. VT-BSE Document No. 2012-0011. Submitted to the Virginia Department of Environmental Quality, Richmond, Virginia.

NASS. 2009. Cropland Data Layer. USDA National Agricultural Statistics Service. Available at: http://www.nass.usda.gov/research/Cropland/SARS1a.htm. Accessed 2 May 2013.

SCS. 1986. Urban hydrology for small watersheds. Technical Release 55 (TR-55). U. S. Department of Agriculture, Soil Conservation Service, Engineering Division. Washington, D.C.

Schneiderman, E.M., D.C. Pierson, D.G. Lounsbury, and M.S. Zion. 2002. Modeling the hydrochemistry of the Cannonsville Watershed with Generalized Watershed Loading Functions (GWLF). J. Amer. Water Resour. Assoc. 38(5): 1323-1347.

SERCC, 2013. Historical Climate Series for Virginia. Southeast Regional Climate Center. Available at http://www.sercc.com/cgi-bin/sercc/cliMAIN.pl?va6593. Accessed 28 March 2013.

SWCB (State Water Control Board). 2011. 9 VAC 25-260 Virginia Water Quality Standards. Available at: http://www.deq.virginia.gov/Portals/0/DEQ/Water/WaterQualityStandards/WQS_eff_6JAN2011.pdf. Accessed 2 May 2013.

Tetra Tech, 2003. A stream condition index for Virginia non-coastal streams. Prepared for USEPA, USEPA Region 3, and Virginia Department of Environmental Quality. Available at: http://www.deq.virginia.gov/Portals/0/DEQ/Water/WaterQualityMonitoring/BiologicalMonitoring/vsci.pdf . Accessed 2 May 2013.

USDA-NRCS. 2005. Regional Hydraulic Geometry Curves. Available at http://wmc.ar.nrcs.usda.gov/technical/HHSWR/Geomorphic/index.html. Accessed 2 May 2013.

USDA-NRCS. 2012. VA 019 – Amherst County, Virginia. Tabular and spatial data. Soil Data Mart. U.S. Department of Agriculture, Natural Resources Conservation Service. Available at: http://soildatamart.nrcs.usda.gov/. Accessed 2 May 2013.

USDA-NRCS. 2012. Official Soil Series Descriptions (OSD) with series extent mapping capabilities. Available at: http://soils.usda.gov/technical/classification/osd/index.html. Accessed 2 May 2013.

USEPA. 1991. Guidance for water quality-based decisions: The TMDL process. EPA 440/4-91-001. Washington, DG: Office of Water, USEPA.

USEPA. 2000. Stressor identification guidance document. EPA-822-B-00-025. Washington, D.C.: U. S. Environmental Protection Agency, Office of Water and Office of Research and Development.

USEPA. 2002. Mid-Atlantic Eco-regions. Available at: http://www.epa.gov/wed/pages/ecoregions/reg3_eco.htm. Accessed 28 April 2013.

http://www.nass.usda.gov/research/Cropland/SARS1a.htm

http://www.sercc.com/cgi-bin/sercc/cliMAIN.pl?va6593

http://www.deq.virginia.gov/Portals/0/DEQ/Water/WaterQualityStandards/WQS_eff_6JAN2011.pdf

http://www.deq.virginia.gov/Portals/0/DEQ/Water/WaterQualityStandards/WQS_eff_6JAN2011.pdf

http://www.deq.virginia.gov/Portals/0/DEQ/Water/WaterQualityMonitoring/BiologicalMonitoring/vsci.pdf

http://www.deq.virginia.gov/Portals/0/DEQ/Water/WaterQualityMonitoring/BiologicalMonitoring/vsci.pdf

http://wmc.ar.nrcs.usda.gov/technical/HHSWR/Geomorphic/index.html

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http://www.epa.gov/wed/pages/ecoregions/reg3_eco.htm


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USEPA. 2006a. Memorandum from Benjamin H. Grumbles, Subject: Establishing TMDL “Daily” Loads in Light of the Decision by the U.S. Court of Appeals for the D.C. Circuit in Friends of the Earth, Inc. vs. EPA et al., No. 05-5015 (April 25, 2006) and Implications for NPDES Permits, November 15, 2006.

USEPA. 2006b. An Approach for Using Load Duration Curves in the Development of TMDLs. Washington, DC: Office of Wetlands, Oceans, and Watersheds. December 15, 2006.

USEPA. 2010. Chesapeake Bay Phase 5.3 Community Watershed Model. Section 4: Land Use. EPA 903S10002 – CBP/TRS-303-10. December 2010. Annapolis, MD: U.S. Environmental Protection Agency, Chesapeake Bay Program Office. Available at: ftp://ftp.chesapeakebay.net/Modeling/P5Documentation/. Accessed 2 May 2013.

VADEQ. 2008, 2010, 2012. Virginia Water Quality Assessment 305(b)/303(d) Integrated Report. Richmond, Virginia. Available at: http://www.deq.virginia.gov/Programs/Water/WaterQualityInformationTMDLs.aspx. Accessed 28 April 2013.

VADEQ, 2005. Memorandum from Jutta Schneider, entitled “Error in Channel Erosion Calculation using GWLF”. December 16, 2005. Virginia Department of Environmental Quality. Richmond, Virginia.

VADEQ. 2006. Using probabilistic monitoring data to validate the non-coastal Virginia Stream Condition Index. VDEQ Technical Bulletin WQA/2006-001. Richmond, Va.: Virginia Department of Environmental Quality; Water Quality Monitoring, Biological Monitoring and Water Quality Assessment Programs.

Wischmeier, W. H. and D. D. Smith. 1978. Predicting rainfall erosion losses – A guide to conservation planning. Agriculture Handbook 537. Beltsville, Maryland: U.S. Department of Agriculture, Science and Education Administration.

Yagow, G. and W.C. Hession. 2007. Statewide NPS Pollutant Load Assessment in Virginia at the Sixth Order NWBD Level: Final Project Report. VT-BSE Document No. 2007-0003. Submitted to the Virginia Department of Conservation and Recreation, Richmond, Virginia.

Yagow, G. 2004. Using GWLF for development of “reference watershed approach” TMDLs. Paper No. 042262. 2004 ASAE/CSAE Annual International Meeting; Ontario, Canada; July 31 – August 4, 2004. St. Joseph, Mich.: ASAE. 10 pp.

Yagow, G., S. Mostaghimi, and T. Dillaha. 2002. GWLF model calibration for statewide NPS assessment. Virginia NPS pollutant load assessment methodology for 2002 and 2004 statewide NPS pollutant assessments. January 1 – March 31, 2002 Quarterly Report. Submitted to Virginia Department of Conservation and Recreation, Division of Soil and Water Conservation. Richmond, Virginia.

ftp://ftp.chesapeakebay.net/Modeling/P5Documentation/

http://www.deq.virginia.gov/Programs/Water/WaterQualityInformationTMDLs.aspx


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Appendix A: Glossary of Terms

Allocation That portion of a receiving water’s loading capacity that is attributed to one of its existing or future pollution sources (nonpoint or point) or to natural background sources.

Allocation Scenario A proposed series of point and nonpoint source allocations (loadings from different sources), which are being considered to meet a water quality planning goal.

Background levels Levels representing the chemical, physical, and biological conditions that would result from natural geomorphological processes such as weathering and dissolution.

Best Management Practices (BMP) Methods, measures, or practices that are determined to be reasonable and cost- effective means for a land owner to meet certain, generally nonpoint source, pollution control needs. BMPs include structural and nonstructural controls and operation and maintenance procedures.

Hydrology The study of the distribution, properties, and effects of water on the earth’s surface, in the soil and underlying rocks, and in the atmosphere.

Load allocation (LA) The portion of a receiving water’s loading capacity that is attributed either to one of its existing or future nonpoint sources of pollution or to natural background.

Margin of Safety (MOS) A required component of the TMDL that accounts for the uncertainty about the relationship between the pollutant loads and the quality of the receiving waterbody. The MOS is normally incorporated into the conservative assumptions used to develop TMDLs (generally within the calculations or models). The MOS may also be assigned explicitly, as was done in this study, to ensure that the water quality standard is not violated.

Model Mathematical representation of hydrologic and water quality processes. Effects of Land use, slope, soil characteristics, and management practices are included.

Nonpoint source Pollution that is not released through pipes but rather originates from multiple sources over a relatively large area. Nonpoint sources can be divided into source activities related to either land or water use including failing septic tanks, improper animal-keeping practices, forest practices, and urban and rural runoff.

Point source Pollutant loads discharged at a specific location from pipes, outfalls, and conveyance channels from either municipal wastewater treatment plants or industrial waste treatment facilities. Point sources can also include pollutant loads contributed by tributaries to the main receiving water stream or river.

Pollution


55

Generally, the presence of matter or energy whose nature, location, or quantity produces undesired environmental effects. Under the Clean Water Act for example, the term is defined as the man-made or man-induced alteration of the physical, biological, chemical, and radiological integrity of water.

Reach Segment of a stream or river.

Runoff That part of rainfall or snowmelt that runs off the land into streams or other surface water. It can carry pollutants from the air and land into receiving waters.

Simulation The use of mathematical models to approximate the observed behavior of a natural water system in response to a specific known set of input and forcing conditions. Models that have been validated, or verified, are then used to predict the response of a natural water system to changes in the input or forcing conditions.

Total Maximum Daily Load (TMDL) The sum of the individual wasteload allocations (WLA’s) for point sources, load allocations (LA’s) for nonpoint sources and natural background, plus a margin of safety (MOS). TMDLs can be expressed in terms of mass per time, toxicity, or other appropriate measures that relate to a state’s water quality standard.

Urban Runoff Surface runoff originating from an urban drainage area including streets, parking lots, and rooftops.

Wasteload allocation (WLA) The portion of a receiving water’s loading capacity that is allocated to one of its existing or future point sources of pollution. WLAs constitute a type of water quality-based effluent limitation.

Water quality standard Law or regulation that consists of the beneficial designated use or uses of a water body, the numeric and narrative water quality criteria that are necessary to protect the use or uses of that particular water body, and an anti-degradation statement.

Watershed A drainage area or basin in which all land and water areas drain or flow toward a central collector such as a stream, river, or lake at a lower elevation.

For more definitions, see the Virginia Cooperative Extension publications available online:

Glossary of Water-Related Terms. Publication 442-758. http://www.ext.vt.edu/pubs/bse/442-758/442-758.html and TMDLs (Total Maximum Daily Loads) - Terms and Definitions. Publication 442-550. http://www.ext.vt.edu/pubs/bse/442-550/442-550.html.

http://www.ext.vt.edu/pubs/bse/442-758/442-758.html

http://www.ext.vt.edu/pubs/bse/442-550/442-550.html


56

Appendix B: GWLF Model Parameters

The GWLF parameter values used for the Buffalo River and Fishpond Creek

watershed simulations for Existing conditions are shown in Table B-1 through Table B-3.

Table B-1 lists the various watershed-wide parameters and their values, Table B-2

displays the monthly variable evapo-transpiration cover coefficients, and Table B-3

shows the land use-related parameters – runoff curve numbers (CN) and the Universal

Soil Loss Equation’s KLSCP product - used for erosion modeling. Since the modeling

was performed in metric units, note that all of the input parameters are in metric units,

even though the simulated results shown in this report are presented in English units.

Long Branch and B

uffalo River S

ediment TM

DLs

Am

herst County, V

irginia

57

Table B-1. GWLF Watershed Parameters

BUF1 BUF2 BUF3 LOB BUF1x FSP FSPadjLOB FSPadjBUF

Lower Buffalo River

Middlie Buffalo River

Upper Buffalo River Long Branch Combined

Buffalo River Fishpond Creek Fishpond Creek - adjBUF

Fishpond - adjLOB

recession coefficient (day-1) 0.0807 0.1228 0.0725 0.2194 0.0572 0.0761 0.2195 0.0572seepage coefficient 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000leakage coefficient 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000sediment delivery ratio 0.1590 0.1791 0.1491 0.1895 0.1172 0.1541 0.1896 0.1172unsaturated water capacity (cm) 15.10 14.95 14.11 16.41 14.72 17.07 17.07 17.07erosivity coefficient (Nov - Apr) 0.139 0.139 0.139 0.139 0.139 0.110 0.110 0.110erosivity coefficient (growing season) 0.244 0.244 0.244 0.244 0.244 0.201 0.201 0.201% developed land (%) 0.06 0.25 0.03 0.07 0.08 0.01 0.01 0.01no. of livestock (AU) 169 82 55 36 341 154 26 396area-weighted runoff curve number 73.53 75.01 75.68 72.98 74.69 72.86 72.86 72.86area-weighted soil erodibility 0.299 0.299 0.254 0.329 0.280 0.363 0.363 0.363area-weighted slope (%) 26.86 26.17 36.36 19.39 30.26 12.28 12.28 12.28aFactor 0.0000714 0.0000754 0.0000610 0.0000765 0.0000672 0.0000822 0.0000822 0.0000822total stream length (m) 21,732.0 8,779.0 18,725.0 4,394.0 53,630.0 26,981.0 4,626.6 69,426.5mean channel depth (m) 1.007 0.794 0.784 0.618 1.395 1.050 0.617 1.395

GWLF Watershed Parameters units

Buffalo River and Long Branch TMDLs

Table B-2. GWLF Monthly ET Cover Coefficients

Watershed ID Apr May Jun Jul* Aug Sep Oct Nov Dec Jan** Feb MarLower Buffalo River BUF1 0.986 0.994 0.997 0.997 0.970 0.943 0.916 0.863 0.836 0.818 0.907 0.968Middle Buffalo River BUF2 0.984 0.992 0.994 0.994 0.969 0.944 0.919 0.869 0.844 0.827 0.911 0.967Upper Buffalo River BUF3 0.987 0.996 0.999 0.999 0.971 0.943 0.914 0.858 0.830 0.811 0.905 0.969Long Branch LOB 0.985 0.993 0.995 0.995 0.969 0.942 0.915 0.862 0.836 0.818 0.907 0.967Combined Buffalo River BUFx 0.985 0.994 0.996 0.996 0.969 0.942 0.914 0.860 0.833 0.815 0.905 0.967Fishpond Creek FSP 0.987 0.995 0.998 0.998 0.970 0.942 0.914 0.858 0.830 0.811 0.904 0.968Fishpond Creek adjusted for LOB FSPadjLOB 0.987 0.995 0.998 0.998 0.970 0.942 0.914 0.858 0.830 0.811 0.904 0.968Fishpond Creek adjusted for BUF FSPadjBUF 0.987 0.995 0.998 0.998 0.970 0.942 0.914 0.858 0.830 0.811 0.904 0.968* July values represent the maximum composite ET coefficients during the growing season.** Jan values represent the minimum composite ET coefficients during the dormant season.

Table B-3. GWLF Land Use Parameters

Long Branch and B

uffalo River S

ediment TM

DLs

Am

herst County, V

irginia

58

LDI = low intensity developed; MDI = medium intensity developed; HDI = high intensity developed

KLSCP CN KLSCP CN KLSCP CN KLSCP CN KLSCP CN KLSCP CN KLSCP CN KLSCP CNHiTill Rowcrop (hit) 0.1333 91.4 0.2157 92.3 1.1766 93.6 1.5872 91.2 0.2054 92.5 0.6732 91.5 0.6732 91.5 0.6732 91.5LoTill Rowcrop (lot) 0.0281 88.8 0.0456 89.7 0.2485 90.9 0.3352 88.6 0.0434 89.9 0.1422 88.9 0.1422 88.9 0.1422 88.9Pasture (pas_g) 0.0333 72.0 0.0377 73.7 0.0475 75.9 0.0381 71.7 0.0376 74.0 0.0397 72.2 0.0397 72.2 0.0397 72.2Pasture (pas_f) 0.1331 80.8 0.1510 82.1 0.1901 83.8 0.1524 80.5 0.1503 82.3 0.1588 80.9 0.1588 80.9 0.1588 80.9Pasture (pas_p) 0.2362 91.8 0.2680 92.7 0.3375 94.0 0.2705 91.7 0.2669 92.9 0.2818 91.9 0.2818 91.9 0.2818 91.9Riparian pasture (trp) 2.3743 91.8 2.6642 92.7 3.1553 94.0 2.7035 91.7 2.6411 92.9 2.8953 91.9 2.8953 91.9 2.8953 91.9Hay (hay) 0.0682 80.6 0.0454 81.8 0.1173 83.4 0.1009 80.4 0.0642 82.0 0.0887 80.8 0.0887 80.8 0.0887 80.8Forest (for) 0.0120 70.9 0.0117 72.5 0.0105 74.8 0.0099 70.5 0.0113 72.8 0.0066 71.1 0.0066 71.1 0.0066 71.1Harvested forest (hvf) 0.1200 77.5 0.1174 78.9 0.1049 80.8 0.0992 77.2 0.1135 79.1 0.0664 77.6 0.0664 77.6 0.0664 77.6Transitional (barren) 2.4671 99.0 3.4460 99.2 3.0599 99.3 3.0781 99.0 3.0505 99.2 1.8103 99.0 1.8103 99.0 1.8103 99.0Pervious LDI (pur_LDI) 0.0350 80.8 0.0259 82.1 0.0533 83.8 0.0376 80.5 0.0360 82.3 0.0267 80.9 0.0267 80.9 0.0267 80.9Pervious MDI (pur_MDI) 0.0275 80.8 0.0205 82.1 0.0694 83.8 0.0410 80.5 0.0244 82.3 0.0422 80.9 0.0422 80.9 0.0422 80.9Pervious HDI (pur_HDI) 0.0707 80.8 0.0180 82.1 0.0694 83.8 0.0604 80.5 0.0180 82.3 0.0422 80.9 0.0422 80.9 0.0422 80.9Impervious LDI (imp_LDI) 0.0000 100.0 0.0000 100.0 0.0000 100.0 0.0000 100.0 0.0000 100.0 0.0000 100.0 0.0000 100.0 0.0000 100.0Impervious MDI (imp_MDI) 0.0000 100.0 0.0000 100.0 0.0000 100.0 0.0000 100.0 0.0000 100.0 0.0000 100.0 0.0000 100.0 0.0000 100.0Impervious HDI (imp_HDI) 0.0000 100.0 0.0000 100.0 0.0000 100.0 0.0000 100.0 0.0000 100.0 0.0000 100.0 0.0000 100.0 0.0000 100.0

Upper Buffalo River

(BUF3)Fishpond Creek

(FSP)

Middle Buffalo River

(BUF2)

Fishpond Creek adjusted for LOB

(FSPadjLOB)Long Branch

(LOB)

Fishpond Creek adjusted for BUF

(FSPadjBUF)

Combined Buffalo River

(BUF1x)Landuse

Lower Buffalo River

(BUF1)

Documents

Sediment TMDL Development Report for Benthic Impairments ...€¦ · Quality Assessment 305(b)/303(d) Integrated Report (VADEQ, 2008). The Virginia Department of Environmental Quality