Water for Life: Healthy Aquatic Ecosystems: A Desktop Method for Establishing Environmental Flows in Alberta Rivers and Streams

8/6/2019 Water for Life: Healthy Aquatic Ecosystems: A Desktop Method for Establishing Environmental Flows in Alberta Rive

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A Desk-top Method or Establishing EnvironmentalFlows in Alberta Rivers and Streams

healthy aquaticecosystems

water for life


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ii

Disclaimer

This document is an independent report requested by, and prepared or,Alberta Environment. The authors are solely responsible or the interpretationso data and statements made within this report. The report does notnecessarily reect endorsement by, or the policies o Alberta Environment.

Reproduction and Availability

This report and its contents may be reproduced in whole, or in part, providedthat this title page is included with such reproduction and/or appropriateacknowledgements are provided to the authors and sponsors o this project.

Any comments, questions or suggestions on the content o this documentmay be directed to:

Alberta EnvironmentCommunications7th Floor, Petroleum Plaza South Tower

9915-108 StreetEdmonton, AB T5K 2J6Tel: 780.427.2700 (outside o Edmonton dial 310.0000 or toll-ree connection)Fax: 780. 422.4086E-mail: [email protected]: http://environment.gov.ab.ca/ino/home.asp

Additional Copies

Additional print copies o this document are available rom:

Alberta EnvironmentInormation CentreMain Floor, Oxbridge Place9820-106 StreetEdmonton, AB T5K 2J6Tel: 780.427.2700 (outside o Edmonton dial 310.0000 or toll-ree connection)Fax: 780.422.4086E-mail: [email protected]: www.gov.ab.ca/env

Copyright o this publication, regardless o ormat, belongs to Her Majesty the Queen in righto the Province o Alberta. Reproduction o this publication, in whole or in part, regardless o

purpose, requires the prior written permission o Alberta Environment. Her Majesty the Queen in right o the Province o Alberta, 2011

ISBN: 978-0-7785-9978-4 (Print)ISBN: 978-0-7785-9979-1 (Online)


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Authors: Allan Locke and Andrew Paul

April 2011

Alberta Environment and Alberta Sustainable Resource Development

A Desk-top Method or Establishing EnvironmentalFlows in Alberta Rivers and Streams


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The enclosed technical report,A Desk-top Method or Establishing Environmental Flows in Alberta Rivers and

Streams, identifes a method to estimate an ecologically-based ow regime on the basis o reductions rom natural

ow or the per cent exceedance rom natural ow. It also provides background inormation and a jurisdictional

review o current environmental ows (commonly known as instream ow needs) knowledge in North American

and international rivers. The method has been peer reviewed by several instream ow specialists rom academic

and other government jurisdictions. The report was prepared jointly by Alberta Environment and Alberta Sustainable

Resource Development in support o the outcomes and goals identifed in the provincial Water or Lie strategy

and action plan.

The method provides a technique to estimate ows to meet the objective o ull protection o the riverine

environment, in the absence o site-specifc studies, which are time consuming and costly to undertake. The

method was developed primarily or rivers that have natural ows but can also be used to assess the degree o

impact on ows in regulated systems or in those situations where a high degree o allocation currently exists.

While not directly linked to water management acts or legislation, the instream ow needs desk-top method can

provide valuable inormation when considering environmental aspects in balancing natural river ows and water

demand. The technical report provides a science-based water management tool that can support inormed decisions

regarding the environmental considerations o owing rivers and streams o Alberta. In addition to regulatory

activities, many organizations within Alberta in an advisory capacity are undertaking reviews o water availability

and general planning, and this method provides an efcient way to assess environmental ow options.

While the understanding o river ows and the requirements o aquatic ecosystems will improve over time and

the method may need to be updated to reect new inormation, the approach identifed in this technical report is

one way to assess the inuence o water ows on aquatic ecosystems without having to carry out site specifc

studies. In those instances where the method does not address the numerous and complex issues that arise

in water management planning or the allocation process, site specifc studies should be undertaken. Specifc

approaches to manage water across river systems and basins will require a suite o options and tools that

incorporates the ull range o values derived rom the water resource.

Preace


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Executive Summary

Flowing waters in Alberta provide or a rich diversity o plant and animal lie. Sufcient water o good quality

is among the most essential requirements or sustaining fsh and other aquatic lie within Albertas rivers and

streams. At the same time, rivers, and streams are a valuable resource or Albertans, as they provide a diverse

array o social, cultural and economic benefts to them. Consequently, Albertans ace the challenge o maintaining

sustainable environmental conditions in rivers and streams while balancing existing and uture demands on

water resources throughout the province.

Water or Lie: Albertas Strategy or Sustainabilityacknowledges that there are limits to the available water supply

and that, in order or Albertans to live within the capacity o individual watersheds, they need to become leaders

at using water more eectively and efciently. The method described in this document contributes to the achievement

o a Water or Lie action, namely to establish science-based methods or determining the ecological requirements

or a healthy aquatic environment.

As Albertas population continues to grow, demand or water will also grow. The ollowing method or protecting

rivers and streams demonstrates the commitment o the Government o Alberta to ensure the water resources

will be used in an environmentally sustainable manner.

Aquatic Ecosystem Protection

The approach described in this technical document provides a method or setting instream ow requirements

or owing waters in Alberta. Based on a combination o per cent o natural ow and ecosystem base ow

components, the method outlines a science-based recommendation suitable to guide water management

decisions in the absence o site-specifc instream ow inormation. The method is a desktop approach, as

it requires only existing site-specifc natural or naturalized hydrology data.

While having inormation rom site-specifc instream ow needs (IFN) studies is always preerable, there are

many instances where management decisions are made where site-specifc IFN data do not exist, nor are the

resources available to carry out site-specifc studies in a timely manner, or example, water licensing and

administration. Completing detailed IFN studies or every watercourse in the province is likely cost prohibitive.

This method provides a means o making an instream ow recommendation in lieu o detailed studies. I the

need arises to reduce the uncertainty in the IFN recommendation, then site-specifc studies must be carried

out to provide better inormation. Should site-specifc IFN studies be completed, then the recommendation

rom the site-specifc studies would replace the IFN method recommendation.


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Executive Summary(continued)

Flow Regimes Impact Aquatic Resources

It is widely accepted there is an ecological basis or the management o ow regimes o rivers and streams. River

ecosystems entail variable physical, chemical, and biological constituents upon which fsh and other aquatic resources

exist. Environmental conditions, such as, depth, velocity, substrate, and cover temperature, and resources, such

as ood and space, are necessary or species survival. In rivers and streams, the suitability o environmental

conditions or aquatic resources relate directly to the characteristics o the ow regime. However, measurable

biological response has variable lag time depending on lie history and other interactions. This method produces

an ecologically based ow regime that incorporates the spatial and temporal ow conditions necessary to ensure

long-term protection o the aquatic resources. This method or setting instream ows is considered to be the best

that can be used to protect the aquatic ecosystem where no site-specifc data are available.

Method Uses Canadian and International Findings

The method relies on existing or synthesized hydrology and ecological inormation, and draws upon the

experience rom detailed studies carried out in Alberta and elsewhere over the past several decades. Details

o relevant Canadian and international studies are included in Appendix C o this publication.

Intent of the Method

This method is intended to provide guidance or the issuance o water licences in unaltered (limited or no

extractions) owing waters where no site-specifc environmental data exists and where the objective remains

to provide ull protection o the aquatic ecosystem. The method can also be used as a course flter in watershed

management planning initiatives to assess current ow conditions relative to the natural and method ow values.

The method is the basis upon which a ow recommendation can be made without the beneft o site-specifc

biological, chemical, or physical data or knowledge. At the time that knowledge or data is obtained upon

which a more scientifcally deensible instream ow recommendation can be made, then the instream ow

recommendation would be revised. In rivers and streams, the suitability o environmental conditions or aquatic

resources is directly related to the characteristics o the ow regime. This method represents an ecologically

based ow regime that incorporates the spatial and temporal ow conditions necessary to ensure long-term

protection o aquatic environments.

The Method Formula

The ormula or the IFN method is the greater o either:

A 15 per cent instantaneous reduction rom natural ow or,

The lesser o either the natural ow or the 80 per cent exceedance natural ow based on a weekly or monthly

(depending on the availability o hydrology data) time step.


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Acknowledgements

The Alberta Instream Flow Needs Steering Committee provided the initial oversight or this project. The Committee

was comprised o members rom Alberta Environment, Alberta Sustainable Resource Development and Fisheries

and Oceans Canada. Throughout the drating o this document many Alberta Environment sta provided valuable

input. We wish to thank John Mahoney, Wendell Koning, Anil Gupta, Chiadih Chang, Chris Teichreb, Dave McGee,

Pat Marriott, Doug Ohrn, Keith Leggat, Preston McEachern and Sal Figliuzzi or their time and eort.

There were several provincial, state and ederal biologists who kindly provided data and much insightul advice.

We wish to thank: Kevin Mayes, (Texas Parks and Wildlie Department); Cindy Robertson, (Idaho Department

o Fish and Game); Ron Ptolemy, (British Columbia Ministry o Environment); Alisa Richardson and Veronica

Masson, (Rhode Island Department o Environmental Management); and Charlie Pacas, (Parks Canada, Ban

National Park).

Throughout the project Chris Spytz, Michael Seneka, Colin Fraser and Kelly Buziak rom Alberta Environmentprovided managerial, technical and publication support under the Water or Lie Strategy: Healthy Aquatic

Ecosystems initiative.

The fnal drat o the document was critically reviewed by a number o scientists rom across North America.

We wish to thank: Dr. Hal Beecher, (Washington Department o Fish and Wildlie); Dr. Thomas Hardy (Texas State

University); Dr. Donald Orth (Virginia Tech); Dr. Tim Hardin (Oregon Department o Fish and Wildlie); Dr. Robert

Metcale (Ontario Ministry o Natural Resources); Ian Chisholm (Minnesota Department o Natural Resources); and,

Joe Klein (Alaska Department o Fish and Game) or their thoughtul comments.

To everyone who helped, our sincere appreciation.


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Table o Contents

Preace................................................................................................................................................................................................................................................. iv

Executive Summary................................................................................................................................................................................................................... 1

Acknowledgements................................................................................................................................................................................................................... 3

List o Tables.................................................................................................................................................................................................................................... 5

List o Figures ................................................................................................................................................................................................................................. 5

1.0 Introduction .......................................................................................................................................................................................................................... 6

2.0 Managing Aquatic Ecosystems in Alberta the Legislative and Policy Context.................................................... 8

2.1 Key Legislation....................................................................................................................................................................................................... 82.2 Strategies................................................................................................................................................................................................................... 8

3.0 Ecological Principles Riverine Environments .................................................................................................................................. 11

4.0 How to Use the Method or Setting Instream Flow Needs in Alberta............................................................................. 12

4.1 Per cent o Natural Flow Component................................................................................................................................................ 124.1.1 Building Block Approach vs. Per cent o Flow Approach .................................................................................................. 124.1.2 Findings rom International Studies .................................................................................................................................................... 134.1.3 Findings rom Canadian Studies ........................................................................................................................................................... 134.1.4 Considerations and Limitations - Per cent o Natural Flow Component................................................................ 21

4.2 Ecosystem Base Flow Component..................................................................................................................................................... 224.2.1 Ecosystem Base Flows in Alberta........................................................................................................................................................ 254.2.2 Comparing Ecosystem Base Flows .................................................................................................................................................... 28

4.2.3 Considerations and Limitations Ecosystem Base Flow Component .................................................................... 30

4.3 Combining the Per cent o Natural Flow and Ecosystem Base Flow Components....................................... 30

4.4 Example Calculation o the Alberta Instream Flow Method ............................................................................................. 314.4.1 Step 1: Calculate the Per cent o Natural Flow Component............................................................................................ 314.4.2 Step 2: Calculate the Ecosystem Base Flow Component................................................................................................. 324.4.3 Step 3: Combine the Per cent o Natural Flow and

Ecosystem Base Flow Components ................................................................................................................................................. 32

4.5 Considerations when using the Method.......................................................................................................................................... 33

4.6 Summary ................................................................................................................................................................................................................ 34

Appendix A Instream Flows in the Context o Riverine Ecology ............................................................................................... 35

Appendix B - Hydrology Data ........................................................................................................................................................................................ 45

Appendix C - Details o Studies................................................................................................................................................................................... 51

Glossary............................................................................................................................................................................................................................................ 79

List o Acronyms ....................................................................................................................................................................................................................... 85

Reerences and Bibliography ........................................................................................................................................................................................ 87


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Figure 1. Location o the IFN reach boundariesor the Red Deer (RD), Bow (BW), Oldman (OM),St. Mary (SM), Belly (BL), Waterton (W) andSouth Saskatchewan (SS) Rivers. ......................................... 18

Figure 2. The Highwood River study areashowing segment boundaries. ................................................. 19

Figure 3. Athabasca River InstreamFlow Needs Segment Boundaries. ....................................... 20

Figure 4. Channel cross-section water levelsor corresponding ow exceedances. ................................ 22

Figure 5. The natural ow and instream owrecommendation with only a per cent-owreduction component (that is, no EBF) in relationto a critical ow threshold. Both magnitude andduration below the threshold is increased or theIFN recommendation. ..................................................................... 23

Figure 6. Exceedance curves or natural owand the instream ow recommendation with onlya per cent-ow-reduction component (that is, noEBF). Without an EBF, the IFN recommendationshows the lowest natural ow would: a) bereduced urther; and b) increase in requency. ............ 24

Figure 7. Per cent-o-Natural Flowrecommendation or the Clearwater Riveror the frst week o December (Week 49). ...................... 31

Figure 8. Ecosystem Base Flowrecommendation or the Clearwater Riveror the frst week o December (Week 49). ...................... 32

Figure 9. Example natural ow exceedancecurve and IFN determination or the frst weeko December (Week 49). ................................................................ 33

Figure 10. Daily stream ow hydrograph withbase ows, subsistence ows, high-ow pulsesand overbank ows. ......................................................................... 43

Figure 11. Hydrograph showing the graphicalrelationship o discharge with respect to time. ............ 49

Figure 12. Exceedance plot showingthe relationship o discharge expressedas a percentage o time a given dischargeis exceeded (that is, recurrence interval). ........................ 50

Figure 13. Example o the monthly owdistributions o the natural ow (Nat. Flow),drought low- and high-ow (Dlow, Dhigh) andmaintenance low- and high-ow (Mlow, Mhigh)or the Mkomazi River, South Arica, derivedusing the BBM. .................................................................................... 52

Figure 14. Example o determining an EBF. .................. 55

Figure 15. Calculation o minimum owrequirement or 70 per cent habitat retentionbased on the brown trout adult eeding liestage or a large trout river. ......................................................... 57

Figure 16. Klamath and Trinity River Basins. ................ 61

Figure 17. Recommended monthly instreamows below Iron Gate Dam at eachexceedance ow level. ................................................................... 62

Figure 18. Distribution o thresholds inthe relationship between ow and widthat RAPHSA sites................................................................................. 64

Figure 19. Location o Rainy River and LongSault and Manitou rapids study sites. ................................ 68

Figure 20. Habitat exceedance values oestimated breakpoints in weekly wetted areasor segments 2 (summer only), 4 and 5 o thelower Athabasca River. Per cent o weeks withstatistically detectable breakpoints is indicated.Eighty-our weeks were examined or thesummer and 48 or the winter................................................... 77

List of Tables

List of Figures

Table 1. Summary o fsh habitat basedIFN per cent-o-natural ow componentrecommendations.............................................................................. 17

Table 2. Range in weekly Ecosystem BaseFlow per cent exceedance values interpolated

rom detailed studies on fsh habitat, and riparianvegetation within the Province o Alberta........................ 27

Table 3. Monthly Ecosystem Base Flowexceedance values or: Carnation Creek (BritishColumbia), the Peace River (Florida), a portiono the Snake River Basin (Idaho), and Trout Creek(British Columbia). ............................................................................. 28

Table 4. Sources o data orow naturalization. ............................................................................ 48

Table 5. Instream ow recommendationsor the Klamath River below Iron Gate Dam.................. 63

Table 6. Monthly low-ow threshold naturalper cent exceedance values or the Arcadia gauge

site on the Middle Segment o the Peace River inFlorida. ............................................................................................... 66

Table 7. Rhode Island Aquatic Base FlowMonthly Instream Flow Values................................................. 69

Table 8. Trout Creek naturalized meanmonthly ows and conservation ows at pointo diversion. ............................................................................................ 73


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Introduction1.0

Aquatic ecosystems include the ull diversity o rivers, streams, lakes and wetlands, as well as the groundwater

systems linked to them. Aquatic ecosystems provide important ecological services, such as wetlands, helping

to improve water quality, reducing ood peaks and recharging groundwater aquiers. They also provide cultural,

heritage and scientifc values, as well as a rich diversity o plant and animal lie, and support a variety o human

uses, such as fsheries and recreation.

Water is a precious resource required or aquatic ecosystems as well as humans. In some areas o Alberta,

water resources are currently under signifcant pressure to meet human demand. As Albertas population and

economy continue to grow, demand or this renewable but fnite resource will also grow. The Government o

Alberta is committed to work with citizens, communities, and industry to ensure the water resources are being

used in an environmentally sustainable manner.

Alberta has fsh communities o considerable ecological, domestic and recreational importance both regionally

and globally. Albertas fsheries are a high quality resource. Compared with other regions in North America,

Alberta has a relatively low diversity o fsh species (Nelson and Paetz 1992). This low diversity results rom a

combination o Alberta having:

A cold climate;

A dry environment with relatively ew water bodies; and

A more recent history (within the last 13,000 years) that let much o the province as the last area

or recolonization during the last glacial retreat (Joynt and Sullivan 2003).

These actors provide urther reason to careully manage the water that fsh depend upon or survival. Sufcient

water o good quality is among the most essential requirements or sustaining fsh productivity within Albertas

fsh-bearing rivers and lakes. Consequently, Albertans ace the challenge o maintaining these conditions while

satisying expanded needs o industries, municipalities, communities and individuals. Adding to this challenge

are growing demands or water by private, public and commercial developments. Unless these increasing

demands or and uses o Albertas waters are properly managed, they will harm fsh production and other

elements o the aquatic environment through adverse modifcations to ow characteristics in r ivers (instream

ows) and water volumes in lakes.


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To protect aquatic environments, scientifc studies have shown that signifcant changes to the natural-ow

conditions o rivers and streams can adversely aect the biology, water quality, fsh and fsh habitat, and

channel-maintenance processes o riverine and adjacent terrestrial environments.

Ideally, site-specifc inormation, such as, hydrology, water quality, aquatic habitat, and species data is collected

and analyzed to assist provincial water managers set ow targets and objectives that maintain or improve the

health o aquatic environments. However, site-specifc environmental inormation is not always available to

resource managers, and rigorous study o all streams and rivers in Alberta is neither technically nor economically

easible in the short term.

This document describes a science-based method to establish ow recommendations where site-specifc

riverine inormation is not available. The method is intended to provide ull protection to rivers and streams,and is based on the current scientifc literature and site-specifc studies carried out in Alberta, Canada and

other jurisdictions around the world. It is also intended to support the major water strategies within the

Government o Alberta and to ulfl their objectives. The method is not intended to replace site-specifc studies

but rather to provide a reliable tool where no site-specifc data exists. As new knowledge or data becomes

available, then a new instream ow recommendation would be made that would replace the method-based

ow recommendation. The method presented in this report is based on the best current scientifc understanding

o aquatic ecosystems.


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Provincial and ederal legislation, strategies, and their supporting policies, guide aquatic ecosystem

protection and management in Alberta. The documents described in this section provide context or

the need and applicability o the instream ow needs (IFN) method.

2.1 Key Legislation

Water Act

Alberta Environment (AENV) administers the Water Act and its regulations. A primary unction o the Water Act is

to regulate the diversion o water rom surace and groundwater sources. This occurs through licensing protocols,

as well as by means o approvals or activities within waterbodies.

In addition to supplying a streamlined, one-window licensing and approval process or water-related activities

and diversions, the Water Act also provides guidance that:

Allows or water management plans to be developed to address local and regional issues;

Recognizes the importance o protecting Albertas rivers, streams, lakes, and wetlands, by

requiring that a strategy or the aquatic environment be developed as part o the provincial

water management planning ramework;

Encourages cooperation and proactive measures to resolve water-management problems; and

Gives Albertans the opportunity to participate in and provide advice on water management.

Fisheries Acts Federal and Provincial

Both ederal and provincial statutes provide the legal basis or managing fsh and fsh habitat. The ederal

Fisheries Act (Canada) addresses the harmul alteration o fsh habitat and the required compensation. The

Fisheries Act (Alberta) and regulations, proclaimed in 1997, provide or the development and implementation

o regulations to manage the harvest and allocation o use o the fsh resources.

2.2 Key Strategies

Albertas Commitment to Sustainable Development

Albertas Commitment to Sustainable Development (1999) outlines the Government o Albertas accountability

to the people o the province or the sound management o natural resources, as well as or the protection o

the environment. The Commitment provides the ollowing fve points or the management o resources and the

natural environment:

The use o Albertas natural resources shall be sustainable.

The management o Albertas natural resources shall support and promote the Alberta economy.

Albertas environment shall be protected.

Resources shall be managed on an integrated basis.

Albertas natural resources shall be managed or multiple benefts.

Managing Aquatic Ecosystemsin Alberta the Legislative andPolicy Context

2.0


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Water for Life

Water or Lie: Albertas Strategy or Sustainabilityoutlines the Government o Albertas vision or water management

and identifes several outcomes and key directions that balance the social, economic, and environmental aspects

o water and resource management. Water or Lie confrms three key goals (Government o Alberta 2008):

Sae, secure drinking water;

Healthy aquatic ecosystems; and

Reliable, quality water supplies or a sustainable economy.

Water or Lie also commits to the development and use o:

Place-based approaches to manage watersheds through water management planning; andTools to set ecosystem objectives in the absence o detailed studies or site-specifc inormation

(Government o Alberta, 2003).

Fish Conservation Strategy for Alberta: 2006 - 2010

The Fish Conservation Strategy or Alberta: 2006 2010 provides a ramework or the Department o Alberta

Sustainable Resource Development (ASRD) to ensure Albertas fshery resources are conserved and used

sustainably to beneft present and uture Albertans.

The Fish and Wildlie Divisions stewardship role, as described in the strategy, is contained in a policy and

legislative ramework or managing Albertas fsheries. As stated in the strategy:

Maintenance o biodiversity and productivity o aquatic ecosystems helps to maintain healthy sh

populations, which provide social and economic benets to Albertans. Achieving sustainability o sh

stocks and other aquatic resources requires that these resources, and the ecosystems that support them,

be managed in such a way that their long-term viability and productivity are maintained or the benet o

uture generations.

To achieve the habitat maintenance goal, the frst objective is fsh habitat protection:

To maintain the productive capacity o aquatic habitats to support healthy and diverse sh resources.

For every water body in Alberta, site-specifc fsheries management objectives are set or will be set using a

standard approach (Alberta Sustainable Resource Development 2006).


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Managing Aquatic Ecosystems in Alberta the Legislative and Policy Context(continued)2.0

2.2 Key Strategies (continued)

Framework for Water Management Planning and the

Strategy for the Protection of the Aquatic Environment

The Framework or Water Management Planning promotes a watershed model or water management and

a holistic approach or managing aquatic ecosystems. It also outlines water management planning principles

and processes. The ramework applies to all types o waterbodies, including streams, rivers, aquiers, and

lakes. The principles endorsed by the Government o Alberta during the development o the ramework provide

general direction or the establishment o outcomes, objectives, and planning (Alberta Environment 2002).

The principles include:

Water must be managed sustainably;

Water is a vital component o the environment;

Water plays an essential role in a prosperous economy and in balanced economic development;

Water must be managed using an integrated approach with other natural resources;

Water must be managed in consultation with the public; and

Water must be managed and conserved in a air and efcient manner.

The Strategy or the Protection o the Aquatic Environment recognizes that the environment is a complex

natural system o interconnected parts. The strategy confrms Albertas commitment to maintain, restore

or enhance conditions o aquatic environments, and to maintain biological diversity. The strategy stipulates

protection by taking action to sustain current conditions and to restore conditions to their natural state.

This is accomplished through management o our inter-related aquatic ecosystem components:

Water quantity the amount o water available;

Water quality the chemical, biological, and physical characteristics o the water;

Aquatic habitat the physical and biological structure o the water body and the surrounding land; and

Aquatic species the plants and animals living in or associated with water bodies, wetlands,

and riparian areas.


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The presence and absence o specifc fsh habitats depend largely on the dynamics o the physical, biological,

and chemical processes associated with owing water (riverine) systems. The ow regime o a riverine system is

o critical importance to fsh habitat. Recently, many authors have provided detailed discussion on the importance

o ow in terms o magnitude, requency, timing, rate o change, and duration to r iver ecosystems. Po et al.

(1997) provide a detailed discussion o the role o ow as the master variable in riverine systems. The ollowing

key points have been extracted rom that document:

The natural ow regime plays a critical role in sustaining native biodiversity and ecosystem

integrity in rivers.

The physical structure o the riverine system, and thus o the habitat, is defned largely by physical

processes, especially the movement o water and sediment within the channel.

For many riverine species, completion o the lie cycle requires an array o dierent habitat types,

whose availability over time is regulated by the ow regime.The timing or predictability o ow events is critical ecologically because the lie cycles o many

aquatic and riparian species are timed to either avoid or exploit ows o variable magnitudes.

Modifcation o the natural-ow regime dramatically aects both aquatic and riparian species in streams

and rivers.

A ocus on one or a ew species and on minimum ows ails to recognize that what is good or the

ecosystem may not consistently beneft individual species and that what is good or individual species

may not be o beneft to the ecosystem.

Recognizing the natural variability o river ow and explicitly incorporating the fve components o the

natural ow regime (that is, magnitude, requency, duration, timing, and rate o change) into a broader

ramework would constitute a major advance over most present management, which ocuses on minimum

ows and on just a ew species.

In summary, the protection o fsheries must include protection o hydrological and physical processes that

maintain the natural structure and unction o owing water, as well as protecting biological components. A

detailed description o instream ows in context o riverine ecology is ound in Appendix A.

Ecological Principles Riverine Environments3.0


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This section describes the method used in Alberta to calculate instream ow needs (IFN) requirements or those

river reaches where no site-specifc instream ow needs studies exist.

The method is based upon the results o numerous site-specifc studies carried out in Alberta and an extensive

review o instream ow studies and riverine ecology. The calculation has been simplifed so that it only requires

hydrology data. As the name suggests, with the method no eort is expended going into the feld and collecting

any physical, biological or chemical data. The amount and type o hydrology data that is required is discussed in

Appendix B. Using only hydrology data, two calculations are made to develop the instream ow recommendation:

The Per cent o Natural Flow Component; and

The Ecosystem Base Flow Component.

4.1 Per cent of Natural Flow Component

Throughout the world, a ow recommendation that preserves the natural hydrograph, or parts o the natural

hydrograph, has been done by defning:

a reduction rom the natural ow on an instantaneous basis, or

a fxed value depending on a water-year type and season.

The reduction can be either a fxed-ow-value reduction rom natural or a per cent-o-the-natural ow.

The per cent reduction actor can vary depending on the ow range or the time o year.

Today, the advice o the scientifc community points toward using natural-ow characteristics as a reerence

or determining instream ow needs (National Research Council 2005). Natural variability is important to sustain

aquatic and riparian biota, as well as riverine processes. There are basically two general emerging approaches

the building block and the per cent o ow that can be used to set the per cent o natural ow component.

4.1.1 Building Block Approach vs. Per cent of Flow Approach

The building-block approach (King and Louw 1998) sets a recommended instream ow hydrograph, or set

o hydrographs. For example, base ows o a certain magnitude are needed during one season to maintain

aquatic organisms. These base ows can be set at dierent levels in other seasons to enable, or example,

fsh migrations. On top o these ows are higher ow pulses and overbank ows that coincide with the natural

occurrence o high ows. There can be dierent hydrographs or dierent water years (dry, average, wet) to

provide specifc habitat needs or to acilitate various ecological processes. While generally not presented in

studies that use this methodology, these varying ow magnitudes can be converted into a per cent-reduction

actor rom natural ows or each season, week or month.

In the per cent-o-ow approach, levels o allowable ow depletion are expressed as percentages o the natural

ow. This approach is generally applied in unregulated rivers where the natural ow remains relatively intact and

the societal goal is to protect the aquatic ecosystem. The ollowing international and Canadian examples provide

insight into how the per cent-o-ow approach works.

How to Use the Methodor Setting Instream FlowNeeds in Alberta

4.0


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How to Use the Method or SettingInstream Flow Needs in Alberta(continued)4.0

Specifcally or fsh habitat, time series evaluations are a highly recommended approach as thoroughly described

by Bovee et al. (1998). Carrying out fsh habitat time-series analysis requires the development o evaluation

metrics. For fsh habitat studies in Alberta, many potential threshold criteria were investigated with three ultimately

being selected to evaluate the impact o reductions in habitat. Clipperton et al. (2002 and 2003) agreed that,

the dierence in average habitat, the maximum weekly loss in average habitat, and the maximum instantaneous

habitat loss were the most useul metrics or making comparisons.

The overall strategy o the per cent o natural ow component is aimed at identiying an instream ow regime

that, relative to the natural-ow regime, would limit fsh habitat reductions to amounts generally accepted as

small. The rationale is that i habitat reductions are limited to small amounts, one can reasonably assume thata high level o protection has been provided by the IFN determined on this basis.

Clipperton et al. (2002) stated that i the average habitat reduction o the most severely impacted lie stage was

less than 10 per cent, the overall habitat reduction could be considered small in the context o the magnitude o

uncertainties inherent in the habitat calculations. Clipperton et al. (2002) also used other habitat metrics to examine

habitat changes or shorter periods than are represented by average values.

Several metrics were used to evaluate the eects o change in discharge relative to natural conditions or each

o several ow reduction scenarios ranging rom 5 per cent to 30 per cent. Each metric can be used to examine

dierent eects o changes in ow, such as chronic (long-term) impacts or acute (short-term) impacts. Many

metrics were reviewed by Clipperton et al. (2002). A short list o those many metrics that were evaluated are:

Per cent changes in average habitat calculated separately or the 5090 per cent, 1050 per cent,

1090 per cent habitat exceedance ranges.

Maximum weekly loss in average habitat. The habitat averages or each week were calculated

or the period o record or natural and the IFN ow scenario, and the greatest per cent loss rom

natural was reported.

Maximum weekly loss in average habitat calculated separately or the 5090 per cent, 1050 per cent,

1090 per cent habitat exceedance ranges.

Maximum instantaneous habitat loss, which was the greatest single percentage habitat

loss recorded or all weeks in all years.

From their review o the many habitat metrics that were examined, Clipperton et al. (2002) determined a set

o key metrics with appropriate threshold levels would be used to evaluate each ow-reduction scenario.

They agreed the most useul metrics or making comparisons were:

4.1.3 Findings from Canadian Studies (continued)


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(1) Difference in Average Habitat:

The dierence in average habitat was viewed as an indicator o chronic eects o ow reduction on habitat

availability and the aquatic ecosystem over the long term. This metric included data pooled across weeks

and or the entire period o record. Clipperton et al. (2002) considered,

a reduction in average habitat o less than 10 per cent could be considered small in the context o

the magnitude o uncertainties inherent in the habitat calculations and that a high level o protection

would be provided with average habitat losses o less than 10 per cent.

The threshold habitat loss would apply only to the most severely negatively impacted lie stage. All other lie

stages would have had less habitat loss or even habitat gains.

(2) Maximum Weekly Loss in Average Habitat:

Clipperton et al. (2002) considered the maximum weekly loss in average habitat to be an indicator o chronic

eects o ow reduction on habitat availability and the aquatic ecosystem over an intermediate length o time.

The maximum weekly loss in average habitat was used as the evaluation metric. This metric would detect

problems with specifc times o the year. Clipperton et al. (2002) believed that a threshold value slightly higher

than that used or the average habitat metric was appropriate, given the shorter period o time represented by

this metric. A threshold value o 15 per cent was adopted or the maximum weekly loss in average habitat.

(3) Maximum Instantaneous Habitat Loss

The maximum instantaneous habitat metric is based on the habitat available during each individual week over

the period o record under natural ow and under each ow reduction scenario. Although the term instantaneous

is used, the habitat values being evaluated are actually weekly averages, because a weekly time step was used

or all o the modelling. Clipperton et al. (2002) considered the maximum instantaneous habitat loss to represent

acute eects on habitat availability and the aquatic ecosystem. Since the other two evaluation metrics are based

on averaged data, Clipperton et al. (2002) wanted a check to ensure that large habitat losses were not being missed

in the longer-term evaluations. The rationale or including this metric was that an instantaneous habitat loss o

sufcient magnitude might result in signifcant changes to the ecosystem. These changes would persist over a

much longer time period than the duration o the acute habitat reduction. Clipperton et al. (2002) defned an

instantaneous habitat loss o 25 per cent as the threshold value or this metric. This higher threshold is considered

appropriate because the habitat reduction is expected to be short-term. Because the habitat values used are

based on weekly modelling, the actual instantaneous loss or a single day, or or hours within a day, could be

higher than 25 per cent.


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(3) Maximum Instantaneous Habitat Loss (continued)

Clipperton et al. (2002) noted that no single habitat-evaluation metric can adequately assess the change

in habitat rom natural. Impacts o the same habitat loss are greater i it is long term rather than short term.

By using all three metrics, there is a measure o long-term chronic (dierence in average habitat), seasonal

or short-term chronic (maximum weekly loss in average habitat), and acute (maximum instantaneous habitat

loss) impacts on habitat.

Each lie stage or each species o interest was included in the fnal analysis and evaluation metrics were calculated

or each lie stage. The threshold habitat-loss criteria were applied to the most severely negatively impacted liestage, and all other lie stages would have had less habitat loss or habitat gains. Clipperton et al. (2002) suggested

the rationale or this approach is that by protecting the lie stage with the highest ow requirements, all lie stages

with lower ow requirements will also be protected within a variable ow regime.

This approach has been carried out on several reaches o the main stems o the rivers in the South Saskatchewan

River Basin (SSRB) (Figures 1 and 2) and our reaches on the Athabasca River (Figure 3). From these studies, it can

be seen there is a range o ow reductions rom the natural ow where the threshold or one o the three evaluation

criteria is exceeded. To date, based on physical fsh habitat the most conservative result has been a 15 per cent

reduction rom natural ow, or, similarly stated, 85 per cent o the natural ow. It can be seen in Table 1 that a

constant per cent-ow reduction rom natural in the 1530 per cent range is most common. There are three reaches

where the ow-reduction actors are greater than 30 per cent the Bow River (BW4), on the Oldman River (OM 2)

and on the St. Mary River (SM 1). In these cases, it was observed that the output rom the habitat models - the

Weighted Usable Area curves - peaked at a relatively low ow compared to the hydrology o the reach. The curve

peaks were also very broad and not sensitive to ow reductions.




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* Maps o each o the river basins with more detailed inormation are providedon the ollowing pages.** Most conservative instantaneous ow reduction actor.

(Source: Clipperton et al. 2002; 2003; Paul 2006).

River ReachPer cent-o-Natural

Flow Component IFNRecommendation

Per centReduction rom

Natural Flow

South Saskatchewan River Basin*

Red Deer 1 80% 20%

3 80% 20%

5 75% 25%

6 80% 20%

7 75% 25%

Bow 2 75% 25%

4 45% 55%

Oldman 2 60% 40%

3 70% 30%

4 85% 15%**

5 70% 30%

6 80% 20%

7 80% 20%

Belly 1 70% 30%

2 80% 20%

St. Mary 1 60% 40%

Waterton 1 75% 25%

2 80% 20%

Highwood River Basin*

Highwood 2 80% 20%

4 85% 15%**

Athabasca River Basin*

Athabasca 2 73% 27%

3 85% 15%**

4 83% 17%

5 80% 21%

Summary o sh habitat based IFN per cent-o-natural

fow component recommendations.

Table 1.


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The IFN recommendation or the Highwood River study (Clipperton et al. 2002) was made using the fsh habitat

based procedure described above. For the South Saskatchewan River Basin study (Clipperton et al. 2003), the

fsheries component was carried out as described above; however, the fnal IFN determination included a riparian

component. It should be noted the integration o the two instream ow components - fsh habitat and riparian

vegetation - resulted in an IFN recommendation that is not always a constant per cent ow reduction actor rom

the natural ow or the entire range o ows that occur in any given week.



Location o the IFN reach boundaries or the Red Deer (RD), Bow (BW), Oldman (OM),

St. Mary (SM), Belly (BL), Waterton (W) and South Saskatchewan (SS) Rivers.

Figure 1.


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As stated in Clipperton et al. (2003), an evaluation o the riparian vegetation component, (known as the Poplar

Rule Curve), developed in the Oldman River Basin indicated the detailed criteria might not be directly applicable

to all reaches within the SSRB. Furthermore, taking the specifc models developed or cottonwoods (Populus spp.)

and applying them to watersheds elsewhere in the province where these species do not exist is not recommended

(John Mahoney, Alberta Environment, personal communication). Since the method used to determine the instream

ow needs or the riparian vegetation component cannot be applied outside the SSRB, the method is thereore

based solely on the fsh habitat metrics as described above. The underlying assumption is that fsh habitat acts

as the surrogate or all other biological components in the aquatic ecosystem.

The Highwood River study area showing segment boundaries.

Figure 2.


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Athabasca River Instream Flow Needs Segment Boundaries.

Figure 3.


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The approach used in the South Saskatchewan River Basin was applied to the initial phase o a study on the

Athabasca River. Acute, chronic, and long-term habitat metrics were developed or fsh species or two reaches

in the vicinity o Fort McMurray. The metrics that were used were:

Metric 1 (chronic, long-term) a 10 per cent loss in total average habitat rom natural, calculated

as the average using data or all weeks and all years;

Metric 2 (intermediate) a 15 per cent maximum weekly loss o average habitat rom natural, calculated as

the average habitat or each week (that is, week 16, week 17, etc.) using data rom every year in the period

o record (that is, 1958-2004) and the week with the greatest per cent loss rom natural was reported; and

Metric 3 (acute, short-term) a 25 per cent maximum instantaneous habitat loss rom natural, calculated as

the greatest single percentage habitat loss recorded or an individual ow record or all weeks in all years.

Implicit in the criteria listed is that no long-term loss o fsh or other aquatic or riparian resources will be detected.Until such time as rigorous monitoring verifes this assumption, the standard o a small but acceptable loss is only an

assumption based on reasonable understanding. This study is under way with additional data expected or other

reaches, including the delta area. To date, the most conservative ow recommendation or the open-water season

is a 15 per cent reduction rom the natural ow. (See also Appendix C or urther inormation on Canadian studies.)

4.1.4 Considerations and Limitations -Per cent of Natural Flow Component

Determining how transerable any per cent-o-ow actor is between and amongst rivers in the province has not

been done. In the uture, investigation o these relationships could be carried out i the need arises. Alternatively,

it may be more cost-eective to carry out site-specifc studies rather than calibrating a guideline. Pending

urther investigation, and given the uncertainty in the science, plus a desire to protect the aquatic ecosystem,

the most conservative per cent-o-ow reduction recommendation rom all studies carried out in Alberta to date

is recommended. The per cent o natural ow component or a desktop method would be, a 15 per cent

instantaneous reduction rom natural fow or 85 per cent o the instantaneous natural fow.


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Applying only a constant per cent reduction when natural ows are below a critical threshold would increase

negative impacts. Over time, low-ow periods create bottlenecks with respect to aquatic ecosystem production.

Low ows during late summer may limit available fsh-rearing habitat and low ows in the all may limit spawning

habitat. Perhaps most important, low ows during winter limit over-wintering habitat or the ree-swimming lie

stages o fsh and may limit suitable conditions or incubation o eggs.

Without an EBF, a constant per cent ow reduction actor will not protect the aquatic ecosystem during periods

o very low ows. For example, when ows are naturally below a critical threshold, continued withdrawal o water

will result in an increased magnitude and duration (that is, the amount o time) ows are below the threshold.

As shown in Figure 5, a one-day period o ows below the threshold is increased to a 14-day period below

the threshold when an IFN recommendation consists only o a per cent-o-ow component. In some situations,

fsh can survive in isolated pools but not or increased periods o time. Another consequence o having only a

per cent-o-ow component to an IFN recommendation is there would be ows prescribed that are below thenaturally occurring low ow (Figure 6). As well, the requency and duration o ows below the natural low ow

would be increased. Given the stress on the aquatic system is greatest during low ows, a per cent-o-ow actor

by itsel does not provide or adequate protection o the aquatic ecosystem.

The natural fow and instream fow recommendation with only a per cent-fow reduction

component (that is, no EBF) in relation to a critical fow threshold. Both magnitude and

duration below the threshold is increased or the IFN recommendation.

Figure 5.


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4.2 Ecosystem Base Flow Component (continued)

Exceedance curves or natural fow and the instream fow recommendation

with only a per cent-fow-reduction component (that is, no EBF). Without

an EBF, the IFN recommendation shows the lowest natural fow would:

a) be reduced urther; and b) increase in requency.

Figure 6.

Regardless o whether these ows are called ecosystem base ows, subsistence ows, base ows, passby ows

or low-ow cut-os, the intention or their inclusion in an instream ow needs determination is the same they

are designed to protect the aquatic ecosystem during critically low-ow conditions. The EBF represents a ow

at which urther human-induced reductions in ow would result in unacceptable levels o risk to the health o the

aquatic resources. A recent defnition or a subsistence ow put orward by the National Academy o Sciences

(NAS) is,

Subsistence fow is the minimum stream fow needed during critical drought periods to maintain tolerable

water quality conditions and to provide minimal aquatic habitat space or survival o aquatic organisms(National Research Council 2005).


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In some studies, the subsistence ow is calculated using water quality models and water quality guidelines. The

implication o these critically low ow cut-os, or ecosystem base ows to water users, is that there are naturally

occurring ow thresholds or rivers and streams below which it is recommended there be no water abstractions.

Continued water use could require licencees to use other sources o water, or example, recycling, on-site storage

and conjunctive groundwater surace water management.

Even though the concept o an EBF is widely accepted by instream ow practitioners and is part o instream

ow recommendations, specifc detailed research has not been undertaken to defne what an EBF would be or

various river systems. However, there are numerous examples rom around the world where EBFs have been

established using a variety o techniques. The main areas where EBFs were developed are Australia, South Arica,

and the United Kingdom. The latter was in response to the European Union (EU) Water Framework Directive(s)

to protect aquatic resources within the EU (European Parliament and the Council o the European Union 2000).

In Alberta, the United States, and throughout the world, many studies have been carried out where IFN practitioners,

scientists, and agencies responsible or aquatic resource stewardship have included in them EBF recommendations

(as one part o an IFN recommendation). Results rom a number o international and Canadian reports and studies

with EBF recommendations can be ound in Appendix C.

4.2.1 Ecosystem Base Flows in Alberta

In Alberta, the EBFs have been calculated or a number o river reaches throughout the province using fsh

habitat, water quality, and riparian models. The approaches vary slightly depending on available data, but

overall the evaluation metrics and approach is similar. In Alberta, the preerred ormat or presenting instream

ow recommendations is in ow exceedance ormat on either a weekly or monthly time step depending onavailability o hydrology data. A range in EBFs, expressed in per cent exceedance, or all detailed studies

carried out to date in Alberta are shown in Table 2.

Unique EBFs are generated or each week or the period o record. The our dierent EBF values (lowest, average,

median, and highest) are provided to give a sense or the absolute range (lowest and highest) o EBFs that can

occur in any given reach, as well as an indication o the central tendency (average and median). For example, in

Reach 1 o the Red Deer River EBFs were generated or each week o the open water season (Julian weeks 14-44;

April through November) based on period o record 1912 to 1995. Thereore, in Reach 1 there are 31 EBFs, one or

each week, which range rom 78 to 89 per cent exceedance and have a median value o 89 per cent exceedance.

This means almost all the EBF values are equal to 89 per cent exceedance. There is very little variation in the

recommended EBF throughout the open water season.


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As shown in Table 2, site-specifc EBF values or Alberta range rom 38 per cent in the Highwood River to 95 per

cent in the Bow River. The exceedance value or the Highwood River was based on establishing a low-ow period

(late summer, all and early spring) when fsh habitat would oten, and under natural conditions, be limiting

populations (pp. 102-103, Clipperton et al. 2002). In essence, Clipperton et al. (2002) established periods within

the year when water should not be extracted rom the Highwood River, except or years when ows were unusually

high or that period o time. The exceedance value or the Bow River occurred during weeks outside the riparian

growing season (weeks 16-37) and when the ow associated with the 80 per cent habitat exceedance value was

greater than 95 per cent. For the Bow River, the EBF was defned at the 95 per cent ow exceedance (Clipperton

et al. 2003). There is no hard and ast rule or universally accepted fsh habitat minima. Bovee et al. (1998) suggest

a 90 per cent exceedance value, or other event, that can be used to quantiy extreme, low-requency habitatevents. These metrics have been associated with survival rates o early lie history phases o fsh. They suggest

the best approach is to use an average o the lowest habitat events, or example, 80 to 100 per cent

exceedance probabilities.

The majority o EBF values derived rom studies within Alberta all between 78 per cent and 95 per cent ow

exceedance values (Table 2). Excepting the Highwood River, mean and median values all between 80 per cent

and 90 per cent ow exceedance values. While these values should not be overly surprising given how EBFs

were determined, it does indicate an EBF at the 80 per cent ow exceedance value can be applied as a general

rule-o-thumb or providing ull protection to Albertas riverine environments.


4.2.1 Ecosystem Base Flows in Alberta (continued)


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River ReachEcosystem Base Flow*

Lowest Average Median Highest

South Saskatchewan River Basin

Red Deer1 1 78 88 89 896

3 69 86 89 896

5 85 89 89 896

6 82 88 89 94

7 79 84 80 896

Bow1 2 88 90 89 95

4 84 90 89 95

Forty Mile Creek2 90

Pipestone River3 90

Oldman1 2 85 89 89 896

3 79 83 80 896

4 79 85 88 896

5 79 86 89 896

6 78 86 88 896

7 79 87 89 896

Belly1 1 47 82 81 896

2 74 83 81 896

St. Mary1 1 73 85 88 896

Waterton1 1 78 84 81 896

Highwood4 2 40 78 82 95

4 38 73 81 95

Athabasca River Basin

Lower Athabasca River5 2, 4 and 5 80

Except or the lower Athabasca River, values are based on the open-water season (approximately weeks 1444). Baseows determined or maintenance o water quality below municipal centres (by dilution o sewage euent) were urtherexcluded rom the table. Note: A low per cent exceedance value is a high ow value while a high per cent exceedancevalue is a low ow value.

1 Interpolated rom tables in Appendix G o Clipperton et al. (2003).2 From Golder Associates (2002).3 From Roe et al. (1996).4 Interpolated rom tables in Appendix VIII o Clipperton et al. (2002).5 Based on the Athabasca River discussion provided in the current report and Appendix C.6 Maximum EBF values are derived rom 90 per cent ow exceedance or the EBF component o the Poplar Rule Curve

(Clipperton et al. 2003). The 89 per cent values shown result rom interpolating the EBF rom the tables presented inAppendix G o Clipperton et al. (2003).

Range in weekly Ecosystem Base Flow per cent exceedance values interpolated rom

detailed studies on sh habitat, and riparian vegetation within the Province o Alberta.

Table 2.


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In many o the studies rom outside Alberta (available in Appendix C) the EBFs are presented in a number o

varying ormats: fxed-ow values, a percentage o mean annual discharge, etc. The corresponding natural-ow

per cent exceedance values were not presented; thereore, it is not possible to make direct comparisons to the

weekly or monthly EBFs calculated in Alberta. However, some o the studies did present their EBF recommendations

in monthly per cent exceedance values. In some instances, the authors were contacted and they agreed to

re-ormat their ow recommendations in per cent exceedance ormat. Those data are presented in Table 3.

As shown in Table 3, there is considerable variance in the range o per cent exceedance values or the various

rivers. There are many actors that contribute to this variability. First, there is the legal and institutional setting.

For each river, there are dierent ederal, state, and provincial laws and policies governing an instream ow

prescription. The rivers are rom dierent eco-regions having very dierent climates, rainall patterns, slopes,

geophysical properties, and hydrology. The types o organisms and their habitat requirements are also as varied

as the physical properties o the rivers themselves. Some studies were carried out to restore conditions in a

river to bring back species rom near extinction, while others were done to set limits or uture use o water,

thereby protecting existing viable populations. Given that each study was carried out according to its unique

set o circumstances, both rom a biological and physical perspective, as well as the institutional setting, it is

unlikely there would be convergence in absolute terms o the monthly exceedance values.

The unique hydrology or any river can greatly aect the recommended EBF. Relative low per cent exceedance

(high ow) values are reported or Carnation Creek in British Columbia. This is an unregulated system, but one

that is rain driven and not snowmelt driven. In order to protect ries according to a standard protocol or trout,

the amount o ow required in the dry month o August means a very high exceedance value is set to restrict water

users. This illustrates that the dierences in climate and precipitation can greatly impact the monthly per cent

exceedance requirement.


* Data not available

Monthly Ecosystem Base Flow exceedance values or: Carnation Creek (British

Columbia), the Peace River (Florida), a portion o the Snake River Basin (Idaho),

and Trout Creek (British Columbia).

Table 3.

4.2.2 Comparing Ecosystem Base Flows

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Carnation Creek,

British Columbia* * * * * * * 18 * * 65 *

Peace River, Florida * 99 98 96 92 99 * * * * 99 99

Snake River Basin, Idaho 80 80 80 80 80 80 80 80 80 80 80 80

Trout Creek, British Columbia 84 85 90 64 90 77 83 65 81 84 88 84


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At the other extreme, or the Peace River in Florida, it is shown the per cent exceedance values restrict water

use at very low ows in some months. The Peace River is a very low-gradient system and the species that

inhabit the river are very tolerant o low-ow conditions. As long as the fsh can move rom one pool to the next,

no impact to the populations is expected. However, it should be noted that the peer review o this study pointed

out the fsh passage depths were originally derived rom requirements o migratory salmonids in cool, well-oxygenated

waters and raised the question as to whether these standards apply to Floridas warm water streams. They

suggested more research is required to ensure other actors such as high water temperatures, low dissolved

oxygen, algal blooms, and increased predatory pressure do not negatively impact the aquatic ecosystem.

The winter season ecosystem base-ow recommendations or Forty Mile Creek in Ban National Park are set

consistently at 90 per cent or each month. The researchers in this ongoing study acknowledged the uncertainty

in setting an ecosystem base ow and made it a condition o the water licence that a stream ow monitoring program

be carried out during the water-withdrawal period to empirically determine the impacts to the fsh populations(Golder Associates 2002).

For Trout Creek in British Columbia, studies were carried out to develop a water-use plan that protected fsh

and fsh habitat and ensured a secure water supply. To protect the fsh habitat and populations in the creek,

conservation ows were set based on a generalized model o habitat response to varying ow percentages o

the mean annual discharge. It is believed that ows less than the conservation ows will result in an eventual

signifcant reduction in available fsh habitat and associated fsh production. While the approach, specifc methods,

and tools used to set the ecosystem base ows are not the same as those that have been applied in Alberta,

rom a general perspective, the monthly per cent exceedance values are relatively similar (See Tables 2 and 3).

O all the rivers in Table 3, Trout Creek is perhaps the most similar, in terms o climate, slope, geomorphometry,

and species to Alberta east-slope streams.

Another conounding issue in comparing ecosystem base ows is the varying opinions o what is meant by

ully protecting the aquatic ecosystem, or long-term sustainability o fsh stocks. There is no common

defnition and all practitioners approach these defnitions rom their unique perspective. It is understandable and

reasonable to expect there will be dierences in ow recommendations between studies. Notwithstanding these

dierences, the intent o the ecosystem base ow appears to be somewhat similar; to protect the resource

and to set a threshold below which o-stream usage o water would have an adverse eect on the environment.

In general, setting the amount o habitat protection provided by ecosystem base ows requires subjectivity and

sometimes can be arbitrary. Collective understanding on the eects o meeting, or not meeting, an ecosystem

base ow is insufcient to predict the response o the aquatic ecosystem, including specifc details about the

organisms that live in rivers. Rarely when using habitat models is there a point at which a threshold exists between

instream conditions being good or bad. It would be a simple task to speciy critical levels o ow regime change

i it were possible to defne an ecological edge where the degree o impact goes rom minimal to severe. Aquatic

ecosystems are very complicated and it is likely there are continuums o impacts where as ows get lower, habitat

is reduced. In Alberta, as elsewhere, these so-called breakpoints where the rate o change o habitat increases

with decreased ow may be used as a basis or setting the ecosystem base ow. This linking o the point o

greatest change in habitat with change in ow is a reasonable approach. However, there have been no studies

done to show any defnitive biological response. Whether detailed instream-ow studies have been carried out

or a guideline value is being used, the acceptance o an ecosystem base ow will be a ocused point o debate

among all stakeholders.


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It should be noted that all examples o EBFs presented in this section also have a companion per cent-reduction

actor, or fxed-ow-reduction actor, to address the natural-ow paradigm as discussed in Section 2.1. For the

instream ow needs recommendation to address the natural-ow paradigm and to ully protect the aquatic

ecosystem over the long term, both the EBF and the ow-reduction actor are required. An EBF without the

attendant per cent-reduction component would likely not ully protect the aquatic ecosystem.

4.2.2 Comparing Ecosystem Base Flows (continued)

As in the case o the applicability o a single instantaneous ow-reduction actor, similar questions arise or the

EBF. No sensitivity analysis has been carried out with respect to understanding i the most conservative EBF

recommendation, the 80 per cent exceedance value, is applicable between or among watersheds in the province.

Other scientists and authors have recently advocated or the need to understand and account or the dierences

in ow variability among rivers and between watersheds (Arthington et al. 2006, Henriksen et al. 2006). In the

uture, investigating these relationships and validating the method recommendations should be carried out in

Alberta. Alternatively, it may be more cost eective to simply carry out site-specifc studies. Given the uncertainty

in the science and the desire to ully protect the aquatic ecosystems, until urther investigation is completed, the

most conservative EBF recommendation value rom all studies completed in Alberta to date is recommended,

the 80 per cent exceedance natural fow based on a weekly or monthly time step depending on the availability

o hydrology data.

4.2.3 Considerations and Limitations Ecosystem Base Flow Component


4.3 Combining the Per cent of Natural Flowand Ecosystem Base Flow Components

Once the per cent o natural ow and the ecosystem base ow components have been calculated, they

are simply plotted together and the greater o the two values is selected as the IFN ow recommendation.

This is done in a ow duration curve ormat and, depending on the available hydrology data, it is done on

a monthly or weekly time step.


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Depending on the availability o the hydrology data and using natural hydrology data or the stream, ow-

duration curves are created based on a weekly or monthly time step. This is done according to the AlbertaEnvironment standards and practices as described in Appendix B. The natural ow data is reduced by

15 per cent (85 per cent o the natural ow). An example o this calculation is shown in Figure 7.

4.4.1 Step 1: Calculate the Per cent of Natural Flow Component

4.4 Example Calculation of the AlbertaInstream Flow Method

The ollowing provides a detailed example o how to apply the instream ow needs method.

Per cent-o-Natural Flow recommendation or the Clearwater River

or the rst week o December (Week 49).

Figure 7.


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Using the weekly or monthly ow data, set the 80 per cent exceedance natural ow as the EBF or each week

or month. This is a threshold below which there would be no urther out-o-stream use o water. An example o

this calculation is shown in Figure 8. While the per cent exceedance value or each week o the 52 weeks

throughout the year is fxed at 80, the corresponding ow values are dierent or each week. This is due to the

act there is a unique set o hydrology data or each week.

The fnal IFN determination is set by combining the greater o either; a) a 15 per cent instantaneous reduction

rom natural ow or, b) the lesser o either the natural ow or the 80 per cent exceedance natural ow basedon a weekly or monthly time step depending on the availability o hydrology data. An example is shown in

Figure 9.

4.4.2 Step 2: Calculate the Ecosystem Base Flow Component

4.4.3 Step 3: Combine the Per cent of Natural Flowand Ecosystem Base Flow Components


Ecosystem Base Flow recommendation or the Clearwater Riveror the rst week o December (Week 49).

Figure 8.


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Example natural fow exceedance curve and IFN determination

or the rst week o December (Week 49).

Figure 9.

4.5 Considerations When Using the Method

Applying a method based on a simple ormula across a diversity o rivers having unique channel characteristics,

ow regimes, and watershed properties, places the method in the category o one-size-fts-all. While the Alberta

method is designed to address the intra- and inter-annual variability o ow, it may not ully address all riverine

parameters (biological, chemical, and physical) that vary across river and watershed types in a site-specifc

context. There is risk the recommendation may not meet the objective o ully protecting the aquatic ecosystem.

The method should be subject to periodic review to ensure it is updated as new inormation becomes available

and that its application is consistent with the appropriate scale and purposes or which it was developed.

The ow recommendations that result rom using this method are calculated rom hydrology data. These stream

ow records are oten o short duration (20-30 years in length), and may be seasonal records as is oten the case

in northern Alberta (that is, data available or the ice ree season only). A number o studies have documented the

range o hydrologic variability in streams and rivers in Alberta over the last several centuries (Axelson et al. 2009),

and illustrate that translating instrumental records into management systems may not account or the ull range

o variability aquatic ecosystems require.

In Alberta, the winter time period is known to be a sensitive period when naturally occurring low ow conditions

limit productivity. Both low water temperature, which reduces metabolic rates, and the lack o ood are actors


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4.5 Considerations When Using the Method (continued)

4.6 Summary

This method is based on currently accepted inormation and studies on the science o instream ow needs and

a review o available site specifc studies in Alberta, North American and international studies.

The proposed method provides or the protection o aquatic resources:

Based on sound ecological principles that inherently protect the natural variability o the ow regime;

Supported by existing site-specifc studies and research within the province and internationally;

By being conservative given the complexity o aquatic ecosystems and uncertainty in the science; and

By meeting the intent o relevant provincial and ederal legislation.

In rivers and streams, the suitability o environmental conditions or aquatic resources is directly related to thecharacteristics o the ow regime. This method represents an ecologically-based ow regime that incorporates

the spatial and temporal ow conditions necessary to ensure long-term protection o aquatic environments.

The complexity and limited knowledge available on ecosystems results in uncertainty on how best to manage

natural resources such as water. Our understanding o certain riverine components such as water quality, riparian

health, and fsh habitat is arguably more advanced relative to other components such as geomorphology or

population dynamics. Likewise, our understanding o environmental ows is better or the open water period

compared to our understanding o ecosystem processes during the ice-covered period, including the time o

ice ormation and break-up (Beltaos 1995). Until such time that detailed studies and urther research has been

carried out, a precautionary approach is used to set environmental ows.

that make the winter a sensitive time period. Little is known when it comes to winter and how this method

addresses this sensitive time period. When applying this method, it is necessary to address this shortcoming

by analysing the only data that is available - hydrology data - and making a decision to either apply the method

or to apply a higher ow level. Until such time that biological data is available to guide such decisions, best

proessional judgement is all that can be used.

The method does not specifcally account or the vertical connection o surace to groundwater and lateral

connectivity to adjacent oodplain areas. For example, ow changes in a river can inuence other system aspects

such as the physical and biological characteristics o nearby aquatic eatures, or example, wetlands, lakes, small

streams and groundwater resources.

There are upstream and downstream trends in the amount o physical habitat in rivers. Roseneld et al. (2007)

have demonstrated that based on hydraulic geometry, optimal ows or habitat proportionally increase as streams

become smaller and decrease downstream as stream size increases. From their work they conclude these nonlinear

downstream trends in habitat suggest that fxed ow percentage approaches may underestimate optimal ows

or certain types and certain places along streams and rivers, or example, headwaters. Stream ow data is oten

only available or a single location on a river, so assessing trends, much like with the physical habitat, relies on

extrapolation to overall river conditions and characteristics. Others have observed this trend and have suggested

that rivers should be classifed according to river size and that this classifcation should be related to critical

ecological values (Jowett and Hayes 2004).


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Instream Flows in the Contextof Riverine Ecology

Appendix A


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Appendix A -Instream Flows in the Contexto Riverine Ecology

1.0 Ecological Principles

As a science, riverine ecology is relatively new. Many o the conceptual oundations o this new science were

developed by studying streams in Europe, South Arica, and North America that were already highly regulated

(Ward et al. 2001). However, in recent years, the understanding o river ecology has expanded beyond the view

o rivers as stable, single channel, longitudinal corridors that are oten a result o regulation to also include a

more dynamic view o a natural stream channel that has complex interactions with its ood plain and groundwater

zones (Ward et al. 2001). Despite the eorts o natural resource agenc

Documents

Water for Life: Healthy Aquatic Ecosystems: A Desktop Method for Establishing Environmental Flows in Alberta Rivers and Streams