USDA Stream Visual Assessment

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Stream VisualAssessment Protocol

United StatesDepartment of Agriculture

NaturalResourcesConservationService

National Water and Climate Center Technical Note 99–1


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(NWCC Technical Note 99–1, Stream Visual Assessment Protocol, December 1998)

The U. S. Department of Agriculture (USDA) prohibits discrimination in its

programs on the basis of race, color, national origin, gender, religion, age,disability, political beliefs, sexual orientation, and marital or family status.(Not all prohibited bases apply to all programs.) Persons with disabilitieswho require alternative means for communication of program information(Braille, large print, audiotape, etc.) should contact USDA’s TARGET Cen-ter at (202) 720-2600 (voice and TDD).

To file a complaint of discrimination, write USDA, Director, Office of CivilRights, Room 326W, Whitten Building, 14th and Independence Avenue, SW,Washington, DC 20250-9410 or call (202) 720-5964 (voice or TDD). USDA isan equal opportunity provider and employer.

Cover photo: Stream in Clayton County, Iowa, exhibiting an impairedriparian zone.

Issued December 1998


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(NWCC Technical Note 99–1, Stream Visual Assessment Protocol, December 1998)

P r e f a c e This document presents an easy-to-use assessment protocol to evaluate thecondition of aquatic ecosystems associated with streams. The protocol doesnot require expertise in aquatic biology or extensive training. Least-im-pacted reference sites are used to provide a standard of comparison. Theuse of reference sites is variable depending on how the state chooses toimplement the protocol. The state may modify the protocol based on asystem of stream classification and a series of reference sites. Instructionsfor modifying the protocol are provided in the technical information sec-

tion. Aternatively, a user may use reference sites in a less structured man-ner as a point of reference when applying the protocol.

The Stream Visual Assessment Protocol is the first level in a hierarchy of ecological assessment protocols. More sophisticated assessment methodsmay be found in the Stream Ecological Assessment Field Handbook. Thefield handbook also contains background information on basic streamecology. Information on chemical monitoring of surface water and ground-water may be found in the National Handbook of Water Quality Monitoring.

The protocol is designed to be conducted with the landowner. Educationalmaterial is incorporated into the protocol. The document is structured sothat the protocol (pp. 7–20) can be duplicated to provide a copy to thelandowner after completion of an assessment. The assessment is recordedon a single sheet of paper (copied front and back).


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ii (NWCC Technical Note 99–1, Stream Visual Assessment Protocol, December 1998)

This protocol was developed by the Natural Resources Conservation Ser-vice (NRCS) Aquatic Assessment Workgroup. The principal authors wereBruce Newton, limnologist, National Water and Climate Center, NRCS,Portland, OR; Dr. Catherine Pringle, associate professor of AquaticEcology, University of Georgia, Athens, GA; and Ronald Bjorkland, Uni-versity of Georgia, Athens, GA. The NRCS Aquatic Assessment Workgroupmembers provided substantial assistance in development, field evaluation,and critical review of the document. These members were:

Tim Dunne, biologist, NRCS, Annandale, NJRay Erickson, area biologist, NRCS, Texarkana, ARChris Faulkner, aquatic biologist, USEPA, Washington, DCHoward Hankin, aquatic ecologist, Ecological Sciences Division, NRCS,Washington, DCLouis Justice, state biologist, NRCS, Athens, GABetty McQuaid, soil ecologist, Watershed Science Institute, NRCS,Raleigh, NCMarcus Miller, wetlands specialist, Northern Plains Riparian Team, NRCS,Bozeman, MTLyn Sampson, state biologist, NRCS, East Lansing, MITerri Skadeland,

state biologist, NRCS, Lakewood, COKathryn Staley, fisheries biologist, Wildlife Habitat ManagementInstitute, NRCS, Corvallis, ORBianca Streif, state biologist, NRCS, Portland, ORBilly Teels, director, Wetlands Science Institute, NRCS, Laurel, MD

Additional assistance was provided by J anine Castro, geomorphologist,NRCS, Portland, OR; Mark Schuller, fisheries biologist, NRCS, Spokane,WA; Lyle Steffen, geologist, NRCS, Lincoln, NE; and Lyn Townsend,forest ecologist, NRCS, Seattle, WA.

A c k n o w l e d g m e n t s


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(NWCC Technical Note 99–1, Stream Visual Assessment Protocol, December 1998) ii

C o n t e n t s : Introduction 1

What makes for a healthy stream? 1

What's the stream type? 1

Reference sites 2

Using this protocol 3

Reach description 6

Scoring descriptions 7

Channel condition ................................................................................................................. 7

Hydrologic alteration............................................................................................................ 8

Riparian zone......................................................................................................................... 9

Bank stability....................................................................................................................... 10

Water appearance ............................................................................................................... 11Nutrient enrichment ........................................................................................................... 12

Barriers to fish movement ................................................................................................. 12

Instream fish cover ............................................................................................................. 13

Pools ..................................................................................................................................... 14

Insect/invertebrate habitat................................................................................................. 14

Canopy cover....................................................................................................................... 15

Coldwater fishery...................................................................................................... 15

Warmwater fishery ................................................................................................... 15

Manure presence................................................................................................................. 16

Salinity.................................................................................................................................. 16

Riffle embeddedness .......................................................................................................... 17

Macroinvertebrates observed............................................................................................ 17

Technical information to support implementation 21

Introduction ......................................................................................................................... 21

Origin of the protocol ......................................................................................................... 21

Context for use.................................................................................................................... 21

Development........................................................................................................................ 21

Implementation ................................................................................................................... 22

Instructions for modification............................................................................................. 22

References 25

Glossary 27


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iv (NWCC Technical Note 99–1, Stream Visual Assessment Protocol, December 1998)

Appendix A—1997 and 1998 Field Trial Results 31

Purpose and methods......................................................................................................... 31

Results .................................................................................................................................. 31

Discussion ............................................................................................................................ 34

Tables Table A–1 Summary of studies in the field trial 31

Table A–2 Summary of replication results 32

Table A–3 Accuracy comparison data from studies with too few sites 33

to determine a correlation coefficient

Figures Figure 1 Factors that influence the integrity of streams 2

Figure 2 Stream visual assessment protocol worksheet 4

Figure 3 Baseflow, bankfull, and flood plain locations (Rosgen 1996) 6

Figure 4 Relationship of various stream condition assessment 22

methods in terms of complexity or expertise required

and the aspects of stream condition addressed

Figure A–1 Means and standard deviations from the Parker’s Mill 32Creek site in Americus, GA

Figure A–2 Correlation between SVAP and IBI values in the Virginia 33

study

Figure A–3 Correlation between SVAP and Ohio Qualitative Habitat 33

Evaluation Index values in the Virginia study

Figure A–4 Correlation between SVAP and IBI values in the Carolinas 33

study

Figure A–5 Correlation between SVAP and macroinverte-brate index 33values in Carolinas study

Figure A–6 Version 4 scores for VA plotted against version 3 scores 34


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(NWCC Technical Note 99–1, Stream Visual Assessment Protocol, December 1998) 1

Stream Visual Assessment Protocol

I n t r o d u c t i o n

This assessment protocol provides a basic level of stream health evaluation. It can be successfully ap-plied by conservationists with little biological orhydrological training. It is intended to be conductedwith the landowner and incorporates talking points forthe conservationist to use during the assessment. Thisprotocol is the first level in a four-part hierarchy of assessment protocols. Tier 2 is the NRCS Water Qual-ity Indicators Guide, Tier 3 is the NRCS Stream Eco-logical Assessment Field Handbook, and Tier 4 is theintensive bioassessment protocol used by your Statewater quality agency.

This protocol provides an assessment based primarilyon physical conditions within the assessment area. Itmay not detect some resource problems caused byfactors located beyond the area being assessed. Theuse of higher tier methods is required to more fullyassess the ecological condition and to detect problemsoriginating elsewhere in the watershed. However,most landowners are mainly interested in evaluatingconditions on their land, and this protocol is wellsuited to supporting that objective.

Wh a t m a k e s f o r a h e a l t h ys t r e a m ?

A stream is a complex ecosystem in which severalbiological, physical, and chemical processes interact.Changes in any one characteristic or process havecascading effects throughout the system and result inchanges to many aspects of the system.

Some of the factors that influence and determine theintegrity of streams are shown in figure 1. Often sev-eral factors can combine to cause profound changes.

For example, increased nutrient loads alone might notcause a change to a forested stream. But when com-bined with tree removal and channel widening, theresult is to shift the energy dynamics from an aquaticbiological community based on leaf litter inputs to onebased on algae and macrophytes. The resulting chemi-cal changes caused by algal photosynthesis and respi-ration and elevated temperatures may further contrib-ute to a completely different biological community.

Many stream processes are in a delicate balance. Forexample, stream power, sediment load, and channelroughness must be in balance. Hydrologic changesthat increase stream power, if not balanced by greaterchannel complexity and roughness, result in "hungry"water that erodes banks or the stream bottom. In-creases in sediment load beyond the transport capac-ity of the stream leads to deposition, lateral channelmovement into streambanks, and channel widening.

Most systems would benefit from increased complex-ity and diversity in physical structure. Structuralcomplexity is provided by trees fallen into the channel,overhanging banks, roots extending into the flow,pools and riffles, overhanging vegetation, and a variety

of bottom materials. This complexity enhances habitatfor organisms and also restores hydrologic propertiesthat often have been lost.

Chemical pollution is a factor in most streams. Themajor categories of chemical pollutants are oxygendepleting substances, such as manure, ammonia, andorganic wastes; the nutrients nitrogen and phospho-rus; acids, such as from mining or industrial activities;and toxic materials, such as pesticides and salts ormetals contained in some drain water. It is importantto note that the effects of many chemicals depend onseveral factors. For example, an increase in the pH

caused by excessive algal and aquatic plant growthmay cause an otherwise safe concentration of ammo-nia to become toxic. This is because the equilibriumconcentrations of nontoxic ammonium ion and toxicun-ionized ammonia are pH-dependent.

Finally, it is important to recognize that streams andflood plains need to operate as a connected system.Flooding is necessary to maintain the flood plainbiological community and to relieve the erosive forceof flood discharges by reducing the velocity of thewater. Flooding and bankfull flows are also essential

for maintaining the instream physical structure. Theseevents scour out pools, clean coarser substrates(gravel, cobbles, and boulders) of fine sediment, andredistribute or introduce woody debris.

Wh a t 's t h e s t r e a m t y p e ?

A healthy stream will look and function differently indifferent parts of the country and in different parts of the landscape. A mountain stream in a shale bedrock


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2 (NWCC Technical Note 99–1, Stream Visual Assessment Protocol, December 1998)

is different from a valley stream in alluvial deposits.Coastal streams are different from piedmont streams.Figuring out the different types of streams is calledstream classification. Determining what types of streams are in your area is important to assessing thehealth of a particular stream.

There are many stream classification systems. For the

purpose of a general assessment based on biology andhabitat, you should think in terms of a three-levelclassification system based on ecoregion, drainagearea, and gradient. Ecor egi ons are geographic areas inwhich ecosystems are expected to be similar. A na-tional-level ecoregion map is available, and manystates are working to develop maps at a higher level of resolution. Dr ai nage ar ea is the next most importantfactor to defining stream type. Finally, the slope orgradient of the reach you are assessing will help youdetermine the stream type. If you are familiar withanother classification system, such as Rosgen or

Montgomery/Buffington, you should use that system. This protocol may have been adjusted by your stateoffice to reflect stream types common in your area.

R e f e r e n c e s i te s

One of the most difficult issues associated with stream

ecosystems is the question of historic and potentialconditions. To assess stream health, we need a bench-mark of what the healthy condition is. We can usuallyassume that historic conditions were healthy. But inareas where streams have been degraded for 150 yearsor more, knowledge of historic conditions may havebeen lost. Moreover, in many areas returning to his-toric conditions is impossible or the historic condi-tions would not be stable under the current hydrology.

Therefore, the question becomes what is the best wecan expect for a particular stream. Scientists havegrappled with this question for a long time, and the

Figure 1 Factors that influence the integrity of streams (modified from Karr 1986)

Nutrients

Adsorption

SolubilitiesAlkalinity

Temperature

D.O.

pH

Turbidity

Disease

Riparianvegetation

Hardness

Seasonalcycles

Nutrients

Sunlight

Siltation

Sinuosity

Current

Substrate

Gradient

Channelmorphology

Width/depth

Bank stability

Organic matterinputs

1° and 2°Production

Instreamcover

Canopy

Competition

Reproduction

Groundwater

Land use High/low

extremes

Precipitation& runoff

Velocity

Organics

Parasitism

Feeding

Predation

Chemicalvariables

Bioticfactors

Energysource

Habitatstructure

FlowRegime

Waterresourceintegrity


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consensus that has emerged is to use reference siteswithin a classification system.

Reference sites represent the best conditions attain-able within a particular stream class. The identifica-tion and characterization of reference sites is anongoing effort led in most states by the water qualityagency. You should determine whether your state has

identified reference sites for the streams in your area.Such reference sites could be in another county or inanother state. Unless your state office has providedphotographs and other descriptive information, youshould visit some reference sites to learn what healthystreams look like as part of your skills development.Visiting reference sites should also be part of yourorientation after a move to a new field office.

Us i n g th i s p r o t o c o l

This protocol is intended for use in the field with thelandowner. Conducting the assessment with the land-owner gives you the opportunity to discuss naturalresource concerns and conservation opportunities.

Before conducting the assessment, you should deter-mine the following information in the field office:

• ecoregion (if in use in your State)• drainage area• stream gradients on the property• overall position on the landscape

Your opening discussion with landowners should start

by acknowledging that they own the land and that youunderstand that they know their operation best. Pointout that streams, from small creeks to large rivers, area resource that runs throughout the landscape—howthey manage their part of the stream affects the entiresystem. Talk about the benefits of healthy streams andwatersheds (improved baseflow, forage, fish, water-fowl, wildlife, aesthetics, reduced flooding down-stream, and reduced water pollution). Talk about howrestoring streams to a healthy condition is now anational priority.

Explain what will happen during the assessment andwhat you expect from them. An example follows:

Thi s assessment w i ll tell us how your str eam i s

doi ng. We’ll n eed to look at secti ons of the str eam tha t

ar e r epr esent ati ve of di fferent condi ti ons. As we do

the assessment we’ll di scuss how the fun cti oni ng of

di ff er ent aspects of the str eam work t o keep the sys-

tem healthy . After w e’re done, we can talk about t he

r esults of the assessment . I may r ecommend fu r ther

assessment work t o better u nderstand what’s goi ng

on. Once we un der stand what i s happeni ng, we can

explore what you w ould li ke to accompli sh wi th your

stream and i deas for i mpr ovi ng i ts condi t i on, i f

necessary.

You need to assess one or more representativereaches. A reach is a length of stream. For this proto-col, the length of the assessment reach is 12 times the

active channel width. The reach should be representa-tive of the stream through that area. If conditionschange dramatically along the stream, you shouldidentify additional assessment reaches and conductseparate assessments for each.

As you evaluate each element, try to work the talkingpoints contained in the scoring descriptions into theconversation. If possible, involve the owner by askinghim or her to help record the scores.

The assessment is recorded on a two-page worksheet.A completed worksheet is shown in figure 2. (A

worksheet suitable for copying is at the end of thisnote.) The stream visual assessment protocol work-sheet consists of two principal sections: reach identifi-cation and assessment. The identification sectionrecords basic information about the reach, such asname, location, and land uses. Space is provided for adiagram of the reach, which may be useful to locatethe reach or illustrate problem areas. On this diagramdraw all tributaries, drainage ditches, and irrigationditches; note springs and ponds that drain to thestream; include road crossings and note whether theyare fords, culverts, or bridges; note the direction of

flow; and draw in any large woody debris, pools, andriffles.

The assessment section is used to record the scoresfor up to 15 assessment elements. Not all assessmentelements will be applicable or useful for your site. Donot score elements that are not applicable. Score anelement by comparing your observations to the de-scriptions provided. If you have difficulty matchingdescriptions, try to compare what you are observing tothe conditions at reference sites for your area.

The overall assessment score is determined by adding

the values for each element and dividing by the num-ber of elements assessed. For example, if your scoresadd up to 76 and you used 12 assessment elements,you would have an overall assessment value of 6.3,which is classified as f a i r . This value provides a nu-merical assessment of the environmental condition of the stream reach. This value can be used as a generalstatement about the "state of the environment" of thestream or (over time) as an indicator of trends incondition.


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Figure 2 Stream visual assessment protocol worksheet

Owners name ___________________________________ Evaluator's name_______________________________ Date ________________

Stream name _______________________________________________ Waterbody ID number ____________________________________

Reach location _____________________________________________________________________________________________________

__________________________________________________________________________________________________________________

Ecoregion ___________________________________ Drainage area _______________________ Gradient__________________________

Applicable reference site _____________________________________________________________________________________________

Land use within drainage (%): row crop ______ hayland ______ grazing/pasture _______ forest ______ residential _______

confined animal feeding operations ______ Cons. Reserve ________ industrial _______ Other: _________________

Weather conditions-today ______________________________________ Past 2-5 days __________________________________________

Active channel width ______________________ Dominant substrate: boulder ______ gravel ______ sand ______ silt ______ mud ______

Site Diagram

Stream Visual Assessment Protocol

Elmer Smith Mary Soylkahn 6-20-99

Camp Creek About 2,000 feet upstream of equipment shed

Cherry Creek north of the Rt 310 bridge

2,200 acres 1.2 %(map)

40

clear clear

x x 15 feet

30 20 10

x

x

x

x

x

x x x x x x

CornFlow

Evidence ofconcentrated

flow

Pasture Riffle

N

P o o l


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Figure 2 Stream visual assessment protocol worksheet—Continued

Channel condition

Hydrologic alteration

Riparian zone

Bank stability

Water appearance

Nutrient enrichment

Barriers to fish movement

Instream fish cover

Pools

Invertebrate habitat

Assessment Scores

Canopy cover

Manure presence

Salinity

Riffle embeddedness

MarcroinvertebratesObserved (optional)

Score only if applicable

9.0 Excellent

Suspected causes of observed problems_____________________________________________________________________

_____________________________________________________________________________________________________

_____________________________________________________________________________________________________

_____________________________________________________________________________________________________

Recommendations______________________________________________________________________________________

_____________________________________________________________________________________________________

_____________________________________________________________________________________________________

_____________________________________________________________________________________________________

_____________________________________________________________________________________________________

_____________________________________________________________________________________________________

_____________________________________________________________________________________________________

_____________________________________________________________________________________________________

_____________________________________________________________________________________________________

(Total divided by number scored)Overall score

10

1

1

5

5

3

3

3

7

7

10

10

5.476/14

This reach is typical of the reaches on the property. Severely

Install 391-Riparian Forest Buffer. Need to encourage livestock away from

3

8

degraded riparian zones lack brush, small trees. Some bank problems from livestock access.

Channel may be widening due to high sediment load. Does not appear to be downcutting.

stream using water sources and shade or exclude livestock. Concentrated flows off fields

need to be spread out in zone 3 of buffer. Relocate fallen trees if they deflect current into

bank–use as stream barbs to deflect current to maintain channel.


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R e a c h d e s c r i p ti o n

The first page of the assessment worksheet recordsthe identity and location of the stream reach. Mostentries are self-explanatory. Waterbody ID andecoregion should be filled out only if these identifica-tion and classification aids are used in your state.

Active channel width can be difficult to determine.However, active channel width helps to characterizethe stream. It is also an important aspect of moreadvanced assessment protocols; therefore, it is worthbecoming familiar with the concept and field determi-nation. For this protocol you do not need to measureactive channel width accurately — a visual estimate of the average width is adequate.

Figure 3 Baseflow, bankfull, and flood plain locations (Rosgen 1996)

Active channel width is the stream width at thebankfull discharge. Bankfull discharge is the flow ratethat forms and controls the shape and size of theactive channel. It is approximately the flow rate atwhich the stream begins to move onto its flood plain if the stream has an active flood plain. The bankfulldischarge is expected to occur every 1.5 years onaverage. Figure 3 illustrates the relationship between

baseflow, bankfull flow, and the flood plain. Activechannel width is best determined by locating the firstflat depositional surface occurring above the bed of the stream (i.e., an active flood plain). The lowestelevation at which the bankfull surface could occur isat the top of the point bars or other sediment depositsin the channel bed. Other indicators of the bankfullsurface include a break in slope on the bank, vegeta-tion change, substrate, and debris. If you are nottrained in locating the bankfull stage, ask the land-owner how high the water gets every year and observethe location of permanent vegetation.

Flood plain Flood plain

BankfullBankfullBaseflow

Baseflow


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Sc o r i n g d e s cr i p ti o n s

Each assessment element is rated with a value of 1 to10. Rate only those elements appropriate to thestream. Using the Stream Visual Assessment Protocolworksheet, record the score that best fits the observa-tions you make based on the narrative descriptionsprovided. Unless otherwise directed, assign the lowest

score that applies. For example, if a reach has aspects

Stream meandering generally increases as the gradientof the surrounding valley decreases. Often, develop-ment in the area results in changes to this meanderingpattern and the flow of a stream. These changes inturn may affect the way a stream naturally does itswork, such as the transport of sediment and the devel-opment and maintenance of habitat for fish, aquatic

insects, and aquatic plants. Some modifications tostream channels have more impact on stream healththan others. For example, channelization and damsaffect a stream more than the presence of pilings orother supports for road crossings.

Active downcutting and excessive lateral cutting areserious impairments to stream function. Both condi-tions are indicative of an unstable stream channel.Usually, this instability must be addressed beforecommitting time and money toward improving otherstream problems. For example, restoring the woodyvegetation within the riparian zone becomes increas-

ingly difficult when a channel is downcutting becausebanks continue to be undermined and the water tabledrops below the root zone of the plants during theirgrowing season. In this situation or when a channel isfairly stable, but already incised from previous down-cutting or mechanical dredging, it is usually necessaryto plant upland species, rather than hydrophytic, or toapply irrigation for several growing seasons, or both.Extensive bank-armoring of channels to stop lateralcutting usually leads to more problems (especiallydownstream). Often stability can be obtained by using

a series of structures (barbs, groins, jetties, deflectors,weirs, vortex weirs) that reduce water velocity, deflectcurrents, or act as gradient controls. These structuresare used in conjunction with large woody debris andwoody vegetation plantings. Hydrologic alterations aredescribed next.

What to look for : Signs of channelization or straight-ening of the stream may include an unnaturallystraight section of the stream, high banks, dikes orberms, lack of flow diversity (e.g., few point bars anddeep pools), and uniform-sized bed materials (e.g., allcobbles where there should be mixes of gravel andcobble). In newly channelized reaches, vegetation maybe missing or appear very different (different species,not as well developed) from the bank vegetation of areas that were not channelized. Older channelizedreaches may also have little or no vegetation or havegrasses instead of woody vegetation. Drop structures(such as check dams), irrigation diversions, culverts,

bridge abutments, and riprap also indicate changes tothe stream channel.

Indicators of downcutting in the stream channelinclude nickpoints associated with headcuts in thestream bottom and exposure of cultural features, suchas pipelines that were initially buried under thestream. Exposed footings in bridges and culvert out-lets that are higher than the water surface during lowflows are other examples. A lack of sediment deposi-tional features, such as regularly-spaced point bars, is

of several narrative descriptions, assign a score basedon the lowest scoring description that contains indica-tors present within the reach. You may record valuesintermediate to those listed. Some background infor-mation is provided for each assessment element, aswell as a description of what to look for. The length of the assessment reach should be 12 times the activechannel width.

Ch a n n e l c o n d i t i o n

Natural channel; nostructures, dikes. Noevidence of down-cutting or excessivelateral cutting.

10

Altered channel; 50%of the reachwith riprap or channel-ization. Dikes or leveesprevent access to theflood plain.

1


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normally an indicator of incision. A low vertical scarpat the toe of the streambank may indicate down-cutting, especially if the scarp occurs on the inside of ameander. Another visual indicator of current or pastdowncutting is high streambanks with woody vegeta-tion growing well below the top of the bank (as achannel incises the bankfull flow line moves down-ward within the former bankfull channel). Excessive

bank erosion is indicated by raw banks in areas of thestream where they are not normally found, such asstraight sections between meanders or on the inside of curves.

braiding of the channel. Rosgen (1996) defines braid-ing as a stream with three or more smaller channels.

These smaller channels are extremely unstable, rarelyhave woody vegetation along their banks, and providepoor habitat for stream biota. A spli t channel, how-ever, has two or more smaller channels (called sidechannels) that are usually very stable, have woodyvegetation along their banks, and provide excellenthabitat.

Conversely, an increase in flood flows or the confine-ment of the river away from its flood plain (from eitherincision or levees) increases the energy available to

transport sediment and can result in bank and channelerosion.

The low flow or baseflow during the dry periods of summer or fall usually comes from groundwaterentering the stream through the stream banks andbottom. A decrease in the low-flow rate will result in asmaller portion of the channel suitable for aquaticorganisms. The withdrawal of water from streams forirrigation or industry and the placement of dams oftenchange the normal low-flow pattern. Baseflow can also

H yd r o l o g i c a l te r a t i o n

Bankfull flows, as well as flooding, are important tomaintaining channel shape and function (e.g., sedi-ment transport) and maintaining the physical habitatfor animals and plants. High flows scour fine sedimentto keep gravel areas clean for fish and other aquaticorganisms. These flows also redistribute larger sedi-ment, such as gravel, cobbles, and boulders, as well aslarge woody debris, to form pool and riffle habitatimportant to stream biota. The river channel and floodplain exist in dynamic equilibrium, having evolved inthe present climatic regime and geomorphic setting.

The relationship of water and sediment is the basis forthe dynamic equilibrium that maintains the form and

function of the river channel. The energy of the river(water velocity and depth) should be in balance withthe bedload (volume and particle size of the sedi-ment). Any change in the flow regime alters this bal-ance.

If a river is not incised and has access to its floodplain, decreases in the frequency of bankfull and out-of-bank flows decrease the river's ability to transportsediment. This can result in excess sediment deposition,channel widening and shallowing, and, ultimately, in

Flooding every 1.5 to 2years. No dams, nowater withdrawals, nodikes or other struc-tures limiting thestream's access to theflood plain. Channel isnot incised.

10

Flooding occurs onlyonce every 3 to 5 years;limited channel incision.

orWithdrawals, althoughpresent, do not affectavailable habitat forbiota.

7

Flooding occurs onlyonce every 6 to 10 years;channel deeply incised.

orWithdrawals significantlyaffect available low flowhabitat for biota.

3

No flooding; channeldeeply incised or struc-tures prevent access toflood plain or damoperations preventflood flows.

orWithdrawals havecaused severe loss of low flow habitat.

orFlooding occurs on a 1-year rain event or less.

1


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be affected by management and land use within thewatershed — less infiltration of precipitation reducesbaseflow and increases the frequency and severity of high flow events. For example, urbanization increasesrunoff and can increase the frequency of flooding toevery year or more often and also reduce low flows.Overgrazing and clearcutting can have similar, al-though typically less severe, effects. The last descrip-

tion in the last box refers to the increased flood fre-quency that occurs with the above watershed changes.

What to look for : Ask the landowner about thefrequency of flooding and about summer low-flowconditions. A flood plain should be inundated duringflows that equal or exceed the 1.5- to 2.0-year flow

event (2 out of 3 years or every other year). Be cau-tious because water in an adjacent field does notnecessarily indicate natural flooding. The water mayhave flowed overland from a low spot in the bankoutside the assessment reach.

Evidence of flooding includes high water marks (suchas water lines), sediment deposits, or stream debris.

Look for these on the banks, on the bankside trees orrocks, or on other structures (such as road pilings orculverts).

Excess sediment deposits and wide, shallow channelscould indicate a loss of sediment transport capacity.

The loss of transport capacity can result in a streamwith three or more channels (braiding).

This element is the width of the natural vegetationzone from the edge of the active channel out onto theflood plain. For this element, the word natural meansplant communities with (1) all appropriate structuralcomponents and (2) species native to the site or intro-duced species that function similar to native species atreference sites.

A healthy riparian vegetation zone is one of the mostimportant elements for a healthy stream ecosystem.

The quality of the riparian zone increases with thewidth and the complexity of the woody vegetationwithin it. This zone:• Reduces the amount of pollutants that reach the

stream in surface runoff.• Helps control erosion.• Provides a microclimate that is cooler during the

summer providing cooler water for aquatic organ-isms.

• Provides large woody debris from fallen trees andlimbs that form instream cover, create pools, stabi-lize the streambed, and provide habitat for streambiota.

• Provides fish habitat in the form of undercut bankswith the "ceiling" held together by roots of woodyvegetation.

• Provides organic material for stream biota that,among other functions, is the base of the food chainin lower order streams.

• Provides habitat for terrestrial insects that drop inthe stream and become food for fish, and habitatand travel corridors for terrestrial animals.

• Dissipates energy during flood events.• Often provides the only refuge areas for fish during

out-of-bank flows (behind trees, stumps, and logs).

R i p ar i a n z o n e

Natural vegetationextends half of theactive channel widthon each side.

5

Natural vegetationextends a third of the active channelwidth on each side.

orFiltering functionmoderately compro-mised.

3

Natural vegetationextends at leasttwo active channelwidths on eachside.

10

Natural vegetationextends one activechannel width oneach side.

orIf less than onewidth, covers entireflood plain.

8

Natural vegetationless than a third of the active channelwidth on each side.

orLack of regenera-tion.

orFiltering functionseverely compro-mised.

1


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The type, timing, intensity, and extent of activity inriparian zones are critical in determining the impact onthese areas. Narrow riparian zones and/or riparianzones that have roads, agricultural activities, residen-tial or commercial structures, or significant areas of bare soils have reduced functional value for thestream. The filtering function of riparian zones can becompromised by concentrated flows. No evidence of

concentrated flows through the zone should occur or,if concentrated flows are evident, they should be fromland areas appropriately buffered with vegetatedstrips.

What to look for : Compare the width of the riparianzone to the active channel width. In steep, V-shapedvalleys there may not be enough room for a flood plainriparian zone to extend as far as one or two activechannel widths. In this case, observe how much of theflood plain is covered by riparian zone. The vegetation

must be natural and consist of all of the structuralcomponents (aquatic plants, sedges or rushes, grasses,forbs, shrubs, understory trees, and overstory trees)appropriate for the area. A common problem is lack of shrubs and understory trees. Another common prob-lem is lack of regeneration. The presence of onlymature vegetation and few seedlings indicates lack of regeneration. Do not consider incomplete plant com-

munities as natural. Healthy riparian zones on bothsides of the stream are important for the health of theentire system. If one side is lacking the protectivevegetative cover, the entire reach of the stream will beaffected. In doing the assessment, examine both sidesof the stream and note on the diagram which side of the stream has problems. There should be no evidenceof concentrated flows through the riparian zone thatare not adequately buffered before entering the ripar-ian zone.

This element is the existence of or the potential fordetachment of soil from the upper and lower streambanks and its movement into the stream. Some bankerosion is normal in a healthy stream. Excessive bankerosion occurs where riparian zones are degraded orwhere the stream is unstable because of changes inhydrology, sediment load, or isolation from the flood

plain. High and steep banks are more susceptible toerosion or collapse. All outside bends of streamserode, so even a stable stream may have 50 percent of its banks bare and eroding. A healthy riparian corridorwith a vegetated flood plain contributes to bank stabil-ity. The roots of perennial grasses or woody vegetationtypically extend to the baseflow elevation of water instreams that have bank heights of 6 feet or less. Theroot masses help hold the bank soils together andphysically protect the bank from scour during bankfull

and flooding events. Vegetation seldom becomesestablished below the elevation of the bankfull surfacebecause of the frequency of inundation and the un-stable bottom conditions as the stream moves itsbedload.

The type of vegetation is important. For example,

trees, shrubs, sedges, and rushes have the type of rootmasses capable of withstanding high streamflowevents, while Kentucky bluegrass does not. Soil type atthe surface and below the surface also influences bankstability. For example, banks with a thin soil coverover gravel or sand are more prone to collapse thanare banks with a deep soil layer.

B a n k s ta b i l i ty

Banks are stable; banksare low (at elevation of active flood plain); 33%ormore of eroding surfacearea of banks in outsidebends is protected byroots that extend to thebase-flow elevation.

10

Moderately stable; banksare low (at elevation of active flood plain); lessthan 33%of eroding sur-face area of banks inoutside bends is protectedby roots that extend to thebaseflow elevation.

7

Moderately unstable;banks may be low, buttypically are high (flood-ing occurs 1 year out of 5or less frequently); out-side bends are activelyeroding (overhangingvegetation at top of bank,some mature trees fallinginto steam annually, someslope failures apparent).

3

Unstable; banks may below, but typically are high;some straight reaches andinside edges of bends areactively eroding as well asoutside bends (overhang-ing vegetation at top of bare bank, numerousmature trees falling intostream annually, numerousslope failures apparent).

1


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What to look for : Signs of erosion include unvegetatedstretches, exposed tree roots, or scalloped edges. Evi-dence of construction, vehicular, or animal paths nearbanks or grazing areas leading directly to the water'sedge suggest conditions that may lead to the collapse of banks. Estimate the size or area of the bank affectedrelative to the total bank area. This element may bedifficult to score during high water.

This element compares turbidity, color, and othervisual characteristics with a healthy or referencestream. The depth to which an object can be clearlyseen is a measure of turbidity. Turbidity is caused

mostly by particles of soil and organic matter sus-pended in the water column. Water often shows someturbidity after a storm event because of soil and or-ganic particles carried by runoff into the stream orsuspended by turbulence. The water in some streamsmay be naturally tea-colored. This is particularly truein watersheds with extensive bog and wetland areas.Water that has slight nutrient enrichment may supportcommunities of algae, which provide a greenish colorto the water. Streams with heavy loads of nutrients havethick coatings of algae attached to the rocks and othersubmerged objects. In degraded streams, floating algalmats, surface scum, or pollutants, such as dyes and oil,

may be visible.

Wa t e r a p p e a r a n c e

Very clear, or clear buttea-colored; objectsvisible at depth 3 to 6 ft(less if slightly colored);no oil sheen on surface;no noticeable film onsubmerged objects orrocks.

10

What to look for : Clarity of the water is an obviousand easy feature to assess. The deeper an object in thewater can be seen, the lower the amount of turbidity.Use the depth that objects are visible only if the

stream is deep enough to evaluate turbidity using thisapproach. For example, if the water is clear, but only 1foot deep, do not rate it as if an object became ob-scured at a depth of 1 foot. This measure should betaken after a stream has had the opportunity to "settle"following a storm event. A pea-green color indicatesnutrient enrichment beyond what the stream cannaturally absorb.

Occasionally cloudy,especially after stormevent, but clears rapidly;objects visible at depth 1.5to 3 ft; may have slightlygreen color; no oil sheenon water surface.

7

Considerable cloudinessmost of the time; objectsvisible to depth 0.5 to 1.5ft; slow sections mayappear pea-green; bottomrocks or submerged ob-

jects covered with heavygreen or olive-green film.

or

Moderate odor of ammo-nia or rotten eggs.

3

Very turbid or muddyappearance most of thetime; objects visible todepth < 0.5 ft; slow mov-ing water may be bright-green; other obviouswater pollutants; floatingalgal mats, surface scum,sheen or heavy coat of

foam on surface.orStrong odor of chemicals,oil, sewage, other pollut-ants.

1


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N u tr i e n t e n r i c h m e n t

What to look for : Some aquatic vegetation (rootedmacrophytes, floating plants, and algae attached tosubstrates) is normal and indicates a healthy stream.Excess nutrients cause excess growth of algae andmacrophytes, which can create greenish color to thewater. As nutrient loads increase the green becomesmore intense and macrophytes become more lush and

deep green. Intense algal blooms, thick mats of algae,or dense stands of macrophytes degrade water qualityand habitat. Clear water and a diverse aquatic plantcommunity without dense plant populations are opti-mal for this characteristic.

Nutrient enrichment is often reflected by the types andamounts of aquatic vegetation in the water. High levelsof nutrients (especially phosphorus and nitrogen)promote an overabundance of algae and floating androoted macrophytes. The presence of some aquaticvegetation is normal in streams. Algae and macro-phytes provide habitat and food for all stream animals.

However, an excessive amount of aquatic vegetation isnot beneficial to most stream life. Plant respirationand decomposition of dead vegetation consume dis-solved oxygen in the water. Lack of dissolved oxygencreates stress for all aquatic organisms and can causefish kills. A landowner may have seen fish gulping forair at the water surface during warm weather, indicat-ing a lack of dissolved oxygen.

B a r r i e r s to f i s h m o v e m e n t

Barriers that block the movement of fish or otheraquatic organisms, such as fresh water mussels, mustbe considered as part of the overall stream assess-

ment. If sufficiently high, these barriers may preventthe movement or migration of fish, deny access toimportant breeding and foraging habitats, and isolatepopulations of fish and other aquatic animals.

What to look for : Some barriers are natural, such aswaterfalls and boulder dams, and some are developedby humans. Note the presence of such barriers alongthe reach of the stream you are assessing, their size,

and whether provisions have been made for the pas-sage of fish. Ask the landowner about any dams orother barriers that may be present 3 to 5 miles up-

stream or downstream. Larger dams are often notedon maps, so you may find some information evenbefore going out into the field. Beaver dams generallydo not prevent fish migration. Look for structures thatmay not involve a drop, but still present a hydraulicbarrier. Single, large culverts with no slope and suffi-cient water depth usually do not constitute a barrier.Small culverts or culverts with slopes may cause highwater velocities that prevent passage.

Clear water along entirereach; diverse aquaticplant community in-cludes low quantities of many species of macro-phytes; little algalgrowth present.

10

Fairly clear or slightlygreenish water alongentire reach; moderatealgal growth on streamsubstrates.

7

Greenish water along entirereach; overabundance of lush green macrophytes;abundant algal growth,especially during warmermonths.

3

Pea green, gray, or brownwater along entire reach;dense stands of macro-phytes clog stream;severe algal bloomscreate thick algal mats instream.

1

No barriers

10

Seasonal waterwithdrawals inhibitmovement withinthe reach

8

Drop structures,culverts, dams, ordiversions (< 1 footdrop) within thereach

5

Drop structures,culverts, dams, ordiversions (> 1 footdrop) within 3 milesof the reach

3

Drop structures,culverts, dams, ordiversions (> 1foot drop) withinthe reach

1


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I n s t r e a m f i s h c o ve r

Boulders/cobble—Boulders are rounded stones morethan 10 inches in diameter or large slabs more than 10inches in length; cobbles are stones between 2.5 and10 inches in diameter.

Undercut banks—Eroded areas extending horizon-tally beneath the surface of the bank forming underwa-ter pockets used by fish for hiding and protection.

Thick root mats—Dense mats of roots and rootlets(generally from trees) at or beneath the water surfaceforming structure for invertebrate attachment and fishcover.

Dense macrophyte beds—Beds of emergent (e.g.,water willow), floating leaf (e.g., water lily), or sub-merged (e.g., riverweed) aquatic vegetation thickenough to provide invertebrate attachment and fishcover.

Riffles—Area characterized by broken water surface,rocky or firm substrate, moderate or swift current, andrelatively shallow depth (usually less than 18 inches).

Isolated/backwater pools—Areas disconnectedfrom the main channel or connected as a "blind" sidechannel, characterized by a lack of flow except inperiods of high water.

This assessment element measures availability of physical habitat for fish. The potential for the mainte-nance of a healthy fish community and its ability torecover from disturbance is dependent on the varietyand abundance of suitable habitat and cover available.

What to look for : Observe the number of differenthabitat and cover typeswi thi n a r epresentati ve sub- secti on of t he assessmen t reach that is equivalent inlength to f i ve t i mes the active channel width. Eachcover type must be present in appreciable amounts toscore. Cover types are described below.

Logs/large woody debris—Fallen trees or parts of trees that provide structure and attachment for aquaticmacroinvertebrates and hiding places for fish.

Deep pools—Areas characterized by a smooth undis-turbed surface, generally slow current, and deep

enough to provide protective cover for fish (75 to 100%deeper than the prevailing stream depth).

Overhanging vegetation— Trees, shrubs, vines, orperennial herbaceous vegetation that hangs immedi-ately over the stream surface, providing shade andcover.

>7 cover typesavailable

10

6 to 7 cover typesavailable

8


5


3

None to 1 covertype available

1

Cover types: Logs/large woody debris, deep pools, overhanging vegetation, boulders/cobble, riffles,undercut banks, thick root mats, dense macrophyte beds, isolated/backwater pools,

other: ___________________________________.


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P o o l s

What to look for : Pool diversity and abundance areestimated based on walking the stream or probingfrom the streambank with a stick or length of rebar.

You should find deep pools on the outside of meanderbends. In shallow, clear streams a visual inspectionmay provide an accurate estimate. In deep streams orstreams with low visibility, this assessment character-istic may be difficult to determine and should not be

scored.

Pools are important resting and feeding sites for fish.A healthy stream has a mix of shallow and deep pools.A deep pool is 1.6 to 2 times deeper than the prevailingdepth, while a shallow pool is less than 1.5 timesdeeper than the prevailing depth. Pools are abundant if a deep pool is in each of the meander bends in thereach being assessed. To determine if pools are abun-dant, look at a longer sample length than one that is 12

active channel widths in length. Generally, only 1 or 2pools would typically form within a reach as long as 12active channel widths. In low order, high gradientstreams, pools are abundant if there is more than onepool every 4 channel widths.

Stable substrate is important for insect/invertebratecolonization.Substrate refers to the stream bottom,

woody debris, or other surfaces on which inverte-brates can live. Optimal conditions include a variety of substrate types within a relatively small area of thestream (5 times the active channel width). Stream andsubstrate stability are also important. High streamvelocities, high sediment loads, and frequent floodingmay cause substrate instability even if substrate ispresent.

What to look for : Observe the number of differenttypes of habitat and cover within a representative

subsection of the assessment reach that is equivalentin length to five times the active channel width. Eachcover type must be present in appreciable amounts toscore.

I n s e c t /i n v e r te b r a t e h a b i t a t

Deep and shallow poolsabundant; greater than30%of the pool bottomis obscure due to depth,or the pools are at least5 feet deep.

10

Pools present, but notabundant; from 10 to 30%of the pool bottom isobscure due to depth, orthe pools are at least 3feet deep.

7

Pools present, but shal-low; from 5 to 10%of thepool bottom is obscuredue to depth, or the poolsare less than 3 feet deep.

3

Pools absent, or theentire bottom is dis-cernible.

1

1 to 2 types of habitat. Thesubstrate is often dis-

turbed, covered, or re-moved by high streamvelocities and scour or bysediment deposition.

3

At least 5 types of habitatavailable. Habitat is at a

stage to allow full insectcolonization (woodydebris and logs notfreshly fallen).

10

3 to 4 types of habitat.Some potential habitat

exists, such as overhangingtrees, which will providehabitat, but have not yetentered the stream.

7

None to 1 type of habitat.

1

Cover types: Fine woody debris, submerged logs, leaf packs, undercut banks, cobble, boulders,

coarse gravel, other: _________________________________________.


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Do not assess this element i f act i ve chan nel

wi d th is gr eater t han 50 feet . Do not assess th i s

element i f w oody vegeta t ion is nat ur a l l y ab sent

(e.g., wet mead ows) .

Shading of the stream is important because it keepswater cool and limits algal growth. Cool water has agreater oxygen holding capacity than does warmwater. When streamside trees are removed, the streamis exposed to the warming effects of the sun causingthe water temperature to increase for longer periodsduring the daylight hours and for more days during theyear. This shift in light intensity and temperaturecauses a decline in the numbers of certain species of fish, insects, and other invertebrates and some aquaticplants. They may be replaced altogether by otherspecies that are more tolerant of increased light inten-

sity, low dissolved oxygen, and warmer water tem-perature. For example, trout and salmon require cool,oxygen-rich water. Loss of streamside vegetation (andalso channel widening) that cause increased watertemperature and decreased oxygen levels are majorcontributing factors to the decrease in abundance of trout and salmon from many streams that historicallysupported these species. Increased light and the

warmer water also promote excessive growth of submerged macrophytes and algae that compromisesthe biotic community of the stream. The temperatureat the reach you are assessing will be affected by the

amount of shading 2 to 3 miles upstream.

What to look for : Try to estimate the portion of thewater surface area for the whole reach that is shadedby estimating areas with no shade, poor shade, andshade. Time of the year, time of the day, and weathercan affect your observation of shading. Therefore, therelative amount of shade is estimated by assuming thatthe sun is directly overhead and the vegetation is infull leaf-out. First evaluate the shading conditions forthe reach; then determine (by talking with the land-owner) shading conditions 2 to 3 miles upstream.Alternatively, use aerial photographs taken during full

leaf out. The following rough guidelines for percentshade may be used:

stream surface not visible .......................................... >90

surface slightly visible or visible only in patches.. 70 – 90

surface visible, but banks not visible...................40 – 70

surface visible and banks visible at times...........20 – 40

surface and banks visible............................................ 90%shaded; full canopy;same shading conditionthroughout the reach.

7

(intentionally blank) < 25%water surfaceshaded in reach.

1

> 75%of water surfaceshaded and upstream 2to 3 miles generallywell shaded.

10

>50%shaded in reach.or

>75%in reach, but up-stream 2 to 3 miles poorlyshaded.

7

20 to 50%shaded.

3

< 20%of water surface inreach shaded.

1


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Ma n u r e p r e s e n c e ( i f a p p l i c a b l e )

Do n ot scor e th is element u nl ess l ivestock opera -

t i ons or human w as te d ischar ges are present .

Manure from livestock may enter the water if livestockhave access to the stream or from runoff of grazingland adjacent to the stream. In some communitiesuntreated human waste may also empty directly intostreams. Manure and human waste increase biochemi-

cal oxygen demand, increase the loading of nutrients,and alter the trophic state of the aquatic biologicalcommunity. Untreated human waste is a health risk.

What to look for : Do not score this element unlesslivestock operations or human waste discharges arepresent. Look for evidence of animal droppings in oraround streams, on the streambank, or in the adjacentriparian zone. Well-worn livestock paths leading to ornear streams also suggest the probability of manure inthe stream. Areas with stagnant or slow-moving watermay have moderate to dense amounts of vegetation or

algal blooms, indicating localized enrichment frommanure.

S a l i n i t y ( i f a p p l i c a b l e )

Do n ot assess thi s element un less elevat ed sal i n-

i t y f rom an th r opogen i c sources i s known to

occur i n the st r eam.

High salinity levels most often occur in arid areas

and in areas that have high irrigation requirements.High salinity can also result from oil and gas welloperations. Salt accumulation in soil causes a break-down of soil structure, decreased infiltration of water,and potential toxicity. High salinity in streams affectsaquatic vegetation, macroinvertebrates, and fish. Saltsare a product of natural weathering processes of soiland geologic material.

What to look for : High salinity levels cause a "burn-ing" or "bleaching" of aquatic vegetation. Wilting, lossof plant color, decreased productivity, and stuntedgrowth are readily visible signs. Other indicatorsinclude whitish salt encrustments on the streambanks

and the displacement of native vegetation by salt-tolerant aquatic plants and riparian vegetation (suchas tamarix or salt cedar).

(Intentionally blank) Aquatic vegetation mayshow significant wilting,bleaching, leaf burn, orstunting; dominance of

salt-tolerant streamsidevegetation.

3

Minimal wilting, bleach-ing, leaf burn, or stuntingof aquatic vegetation;some salt-tolerant stream-

side vegetation.

5

Severe wilting, bleaching,leaf burn, or stunting;presence of only salt-tolerant aquatic vegeta-

tion; most streamsidevegetation salt tolerant.

1

(Intentionally blank) Evidence of livestockaccess to riparian zone.

5

Occasional manure instream or waste storagestructure located on theflood plain.

3

Extensive amount of manure on banks or instream.

or Untreated human wastedischarge pipes present.

1


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R i f f l e e m b e d d e d n e s s( i f a p p l i c a b l e )

Gravel or cobbleparticles are< 20%embedded.

10

Gravel or cobbleparticles are 20 to30%embedded.

8

Gravel or cobbleparticles are 30 to40%embedded.

5

Gravel or cobbleparticles are >40%embedded.

3

Riffle is completelyembedded.

1

Do not a ssess thi s element unl ess r i f f l es ar e

presen t o r th ey ar e a na tu r a l f ea tu re tha t

should be pr esent .

Riffles are areas, often downstream of a pool, wherethe water is breaking over rocks or other debris caus-ing surface agitation. In coastal areas riffles can becreated by shoals and submerged objects. (This ele-ment is sensitive to regional differences and should berelated to reference conditions.) Riffles are critical formaintaining high species diversity and abundance of insects for most streams and for serving as spawningand feeding grounds for some fish species. Embedded-ness measures the degree to which gravel and cobblesubstrate are surrounded by fine sediment. It relatesdirectly to the suitability of the stream substrate ashabitat for macroinvertebrates, fish spawning, and eggincubation.

What to look for : This assessment characteristicshould be used only in riffle areas and in streamswhere this is a natural feature. The measure is thedepth to which objects are buried by sediment. Thisassessment is made by picking up particles of gravelor cobble with your fingertips at the fine sedimentlayer. Pull the particle out of the bed and estimatewhat percent of the particle was buried. Some streamshave been so smothered by fine sediment that theoriginal stream bottom is not visible. Test for completeburial of a streambed by probing with a length of rebar.

Ma c r o i n v e r te b r a t e s o b s e r v e d

This important characteristic reflects the ability of thestream to support aquatic invertebrate animals. How-ever, successful assessment requires knowledge of thelife cycles of some aquatic insects and other macro-invertebrates and the ability to identify them. For thisreason, this is an optional element. The presence of intolerant insect species (cannot survive in pollutedwater) indicates healthy stream conditions. Somekinds of macroinvertebrates, such as stoneflies, may-flies, and caddisflies, are sensitive to pollution and donot live in polluted water; they are considered

Group I. Another group of macroinvertebrates, knownas Group II or facultative macroinvertebrates, cantolerate limited pollution. This group includes damsel-flies, aquatic sowbugs, and crayfish. The presence of Group III macroinvertebrates, including midges,craneflies and leeches, suggests the water is signifi-cantly polluted. The presence of a single Group Ispecies in a community does not constitute gooddiversity and should generally not be given a score of 15.

Very reduced number of species or near absence of all macroinvertebrates.

– 3

Community dominated byGroup I or intolerantspecies with good speciesdiversity. Examplesinclude caddisflies, may-flies, stoneflies, hellgram-mites.

15

Community dominated byGroup II or facultativespecies, such as damsel-flies, dragonflies, aquaticsowbugs, blackflies,crayfish.

6

Community dominated byGroup III or tolerant spe-cies, such as midges,craneflies, horseflies,leeches, aquatic earth-worms, tubificid worms.

2


24/42


What to look for : You can collect macroinverte-brates by picking up cobbles and other submergedobjects in the water. Look carefully for the insects;they are often well camouflaged and may appear aspart of the stone or object. Note the kinds of insects,number of species, and relative abundance of eachgroup of insects/macroinvertebrates. Each of the threeclasses of macroinvertebrates are illustrated on pages

19 and 20. Note that th e scor i ng va lu es for t h is element r an ge fr om – 3 to 15.


25/42


S t r e a mI n v e r t e b r a t e s

Group One TaxaPollution sensitive organisms found in goodquality water.

1 Stonefly Order Plecoptera. 1/2" to1 1/2", 6 legs with hooked tips, antennae,2 hair-line tails. Smooth (no gills) on lowerhalf of body (see arrow).

2 Caddisfly: Order Trichoptera. Up to 1",6 hooked legs on upper third of body, 2hooks at back end. May be in a stick,rock, or leaf case with its head stickingout. May have fluffy gill tufts on under-side.

3 Water Penny: Order Coleoptera. 1/4",flat saucer-shaped body with a raisedbump on one side and 6 tiny legs andfluffy gills on the other side. Immature

beetle.

4 Riffle Beetle: Order Coleoptera. 1/4",oval body covered with tiny hairs, 6 legs,antennae. Walks slowly underwater.Does not swim on surface.

5 Mayfly: Order Ephemeroptera. 1/4" to1", brown, moving, plate-like or featherygills on the sides of lower body (seearrow), 6 large hooked legs, antennae, 2or 3 long hair-like tails. Tails may bewebbed together.

6 Gilled Snail: Class Gastropoda. Shellopening covered by thin plate called

operculum. When opening is facing you,shell usually opens on right.

7 Dobsonfly (Hellgrammite): FamilyCorydalidae. 3/4" to 4", dark-colored, 6legs, large pinching jaws, eight pairsfeelers on lower half of body with pairedcotton-like gill tufts along underside, shortantennae, 2 tails, and 2 pairs of hooks atback end.

Group Two TaxaSomewhat pollution tolerant organisms canbe in good or fair quality water.

8 Crayfish: Order Decapoda. Up to 6", 2large claws, 8 legs, resembles smalllobster.

9 Sowbug: Order Isopoda. 1/4" to 3/4",gray oblong body wider than it is high,more than 6 legs, long antennae.

Source: Izaak Walton League of America,707 Conservation Lane, Gaithersburg, MD20878-2983. (800) BUG-IWLA

Bar line indicate relative size


26/42


Group Two TaxaSomewhat pollution tolerant organisms canbe in good or fair quality water.

10 Scud: Order Amphipoda. 1/4", white togray, body higher than it is wide, swimssideways, more than 6 legs, resemblessmall shrimp.

11 Alderfly Larva: Family Sialedae. 1"long. Looks like small Hellgramite buthas long, thin, branched tail at back end(no hooks). No gill tufts underneath.

12 Fishfly Larva: Family Cordalidae. Upto 1 1/2" long. Looks like smallhellgramite but often a lighter reddish-tan color, or with yellowish streaks. Nogill tufts underneath.

13 Damselfly: Suborder Zygoptera. 1/2"to 1", large eyes, 6 thin hooked legs, 3broad oar-shaped tails, positioned like atripod. Smooth (no gills) on sides oflower half of body. (See arrow.)

14 Watersnipe Fly Larva: FamilyAthericidae (Atherix). 1/4" to 1", pale togreen, tapered body, many caterpillar-like legs, conical head, feathery "horns"at back end.

15 Crane Fly: Suborder Nematocera. 1/3"to 2", milky, green, or light brown, plumpcaterpillar-like segmented body, 4 finger-like lobes at back end.

16 Beetle Larva: Order Coleoptera. 1/4"to 1", light-colored, 6 legs on upper halfof body, feelers, antennae.

17 Dragon Fly: Suborder Anisoptera. 1/2"to 2", large eyes, 6 hooked legs. Wideoval to round abdomen.

18 Clam: Class Bivalvia.

Group Three TaxaPollution tolerant organisms can be in anyquality of water.

19 Aquatic Worm: Class Oligochaeta.1/4" to 2", can be very tiny, thin worm-like body.

20 Midge Fly Larva: Suborder Nemato-cera. Up to 1/4", dark head, worm-likesegmented body, 2 tiny legs on eachside.

21 Blackfly Larva: Family Simulidae. Upto 1/4", one end of body wider. Blackhead, suction pad on other end.

22 Leech: Order Hirudinea. 1/4" to 2",brown, slimy body, ends with suctionpads.

23 Pouch Snail and Pond Snails: ClassGastropoda. No operculum. Breath air.When opening is facing you, shellusually open to left.

24 Other Snails: Class Gastropoda. Nooperculum.Breath air. Snail shell coils inone plane.

Bar line indicate relative size


27/42


Te c h n i c a l i n f o r m a t i o n tos u p p o r t i m p l em e n t a ti o n

I n t r o d u c t i o n

This section provides a guide for implementation of

the Stream Visual Assessment Protocol (SVAP). Thetopics covered in this section include the origin of theprotocol, development history, context for use inrelation to other methods of stream assessment,instructions for modifying the protocol, and refer-ences.

Or i g i n o f th e p r o t o c o l

In 1996 the NRCS National Water and Climate Centersurveyed the NRCS state biologists to determine theextent of activity in stream ecological assessment and

the need for technical support. The survey indicatedthat less than a third of the NRCS states were active insupporting stream assessment within their state. Mostrespondents said they believed they should be moreactive and requested additional support from theNational Centers and Institutes. In response to thesefindings, the NRCS Aquatic Assessment Workgroupwas formed. In their first meeting the workgroupdetermined that a simple assessment protocol wasneeded. The Water Quality Indicators Guide (WQIG)had been available for 8 years, but was not being usedextensively. The workgroup felt a simpler and morestreamlined method was needed as an initial protocolfor field office use.

The workgroup developed a plan for a tiered progres-sion of methods that could be used in the field asconservationists became more skilled in stream as-sessment. These methods would also serve differentassessment objectives. The first tier is a simple 2-pageassessment — the Stream Visual Assessment Protocol(SVAP). The second tier is the existing WQIG. Thethird tier is a series of simple assessment methods thatcould be conducted by conservationists in the field. Anexample of a third tier method would be macro-

invertibrate sampling and identification to the taxo-nomic level of Order. The fourth tier is fairly sophisti-cated methods used in special projects. Examples of fourth tier methods would be fish community sam-pling and quantitative sampling of macroinvertebrateswith shipment of samples to a lab for identification.

The workgroup also found that introductory trainingand a field handbook that would serve as a compre-hensive reference and guidance manual are needed.

These projects are under development as of this writing.

Co n t e x t f o r u s e

The Stream Visual Assessment Protocol is intended tobe a simple, comprehensive assessment of streamcondition that maximizes ease of use. It is suitable as abasic first approximation of stream condition. It canalso be used to identify the need for more accurateassessment methods that focus on a particular aspect

of the aquatic system.

The relationship of the SVAP to other assessmentmethods is shown in figure 4. In this figure a specificreference to a guidance document is provided forsome methods. The horizontal bars indicate whichaspects of stream condition (chemical, physical, orbiological) are addressed by the method. The SVAP isthe simplest method and covers all three aspects of stream condition. As you move upwards in figure 4 themethods provide more accuracy, but also becomemore focused on one or two aspects of stream condi-tion and require more expertise or resources to con-

duct.

The SVAP is intended to be applicable nationwide. Ithas been designed to utilize factors that are leastsensitive to regional differences. However, regionaldifferences are a significant aspect of stream assess-ment, and the protocol can be enhanced by tailoringthe assessment elements to regional conditions. Thenational SVAP can be viewed as a framework that canevolve over time to better reflect State or within-Stateregional differences. Instructions for modification areprovided later in this document.

D e v e l o p m e n t

The SVAP was developed by combining parts of sev-eral existing assessment procedures. Many of thesesources are listed in the references section. Threedrafts were developed and reviewed by the workgroupand others between the fall of 1996 and the spring of 1997. During the summer of 1997, the workgroupconducted a field trial evaluation of the third draft.Further field trials were conducted with the fourthdraft in 1998. A report on the field trial results is ap-

pendix A of this document.

The field trials involved approximately 60 individualsand 182 assessment sites. The field trial consisted of acombination of replication studies (in which severalindividuals independently assessed the same sites) andaccuracy studies (in which SVAP scores were com-pared to the results from other assessment methods).

The average coefficient of variation in the replicationstudies was 10.5 percent. The accuracy results indi-cated that SVAP version 3 scores correlated well with


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other methods for moderately impacted and highquality sites, but that low quality sites were not scoringcorrespondingly low in the SVAP. Conservationists inthe field who participated in the trial were surveyed onthe usability and value of the protocol. The partici-pants indicated that they found it easy to use andthought it would be valuable for their clients.

Revisions were made to the draft to address the defi-ciencies identified in the field trial, and some reassess-ments were made during the winter of 1998 to see howthe revisions affected performance. Performance wasimproved. Additional revisions were made, and thefifth draft was sent to all NRCS state offices, selectedFederal agencies, and other partners for review andcomment during the spring of 1998.

Comments were received from eight NRCS stateoffices, the Bureau of Land Management, and severalNRCS national specialists. Comments were uniformlysupportive of the need for the guidance and for the

document as drafted. Many commenters providedimproved explanatory text for the supporting descrip-tions accompanying the assessment elements. Most of the suggested revisions were incorporated.

I m p l e m e n t a t i o n

The SVAP is issued as a national product. States areencouraged to incorporate it within the Field Office

Technical Guide. The document may be modified byStates. The electronic file for the document may be

downloaded from the National Water and ClimateCenter web site at http://www.wcc.nrcs.usda.gov.

A training course for conservationists in the fieldsuitable for use at the state or area level has beendeveloped to facilitate implementation of the SVAP. Itis designed as either a 1-day or 2-day session. The firstday covers basic stream ecology and use of the SVAP.

The second day includes an overview of severalstream assessment methods, instruction on a macro-invertebrate survey method, and field exercises to

apply the SVAP and macroinvertibrate protocols. Thetraining materials consist of an instructor's guide,slides, video, a macroinvertebrate assessment trainingkit, and a student workbook. Training materials havebeen provided to each NRCS state office.

I n s t r u c t i o n s f o r m o d i f i c a t i o n

The national version of the Stream Visual AssessmentProtocol may be used without modification. It hasbeen designed to use assessment elements that areleast sensitive to regional differences. Nonetheless, it

can be modified to better reflect conditions within ageographic area. Modifying the protocol would havethe following benefits:• The protocol can be made easier to use with narra-

tive descriptions that are closer to the conditionsusers will encounter.

• The protocol can be made more responsive todifferences in stream condition.

• Precision can be improved by modifying elementsthat users have trouble evaluating.

• The rating scale can be calibrated to regionally-based criteria for excellent, good, fair, and poor

condition.

Figure 4 Relationship of various stream condition assessment methods in terms of complexity or expertise required and theaspects of stream condition addressed

Difficultor moreexpertiseneeded

National Handbookof WQ Monitoring Tier 4 Biotic Assessment

Tier 3 Biotic Assessment

WQ Indicators Guide

Stream Visual Assessment

Geomorphic analysis

Proper functioning condition

Simple

BiologicalChemical Physical


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Two parts of the SVAP may be modified—the indi-vidual elements and their narrative descriptions, andthe rating scale for assigning an overall condition ratingof excellent, good, fair, or poor.

The simplest approach to modifying the SVAP is basedon professional experience and judgment. Under thisapproach an interdisciplinary team should be as-

sembled to develop proposed revisions. Revisionsshould then be evaluated by conducting comparisonassessments at sites representing a range of conditionsand evaluating accuracy (correlation between differentassessment methods), precision (reproducibilityamong different users), and ease of use.

A second, more scientifically rigorous method formodifying the protocol is described below. This ap-proach is based on a classification system for streamtype and the use of reference sites.

Step 1 Decide on tenta t i ve num ber of ver s ions.

Do you want to develop a revised version for yourstate, for each ecoregion within your state, or forseveral stream classes within each ecoregion?

Step 2 D evelop t enta t i ve s t ream c lassi f i ca t ion.

If you are developing protocols by stream class, youneed to develop a tentative classification system. (If you are interested in a statewide or ecoregion protocol,go to step 3.) You might develop a classification systembased on stream order, elevation, or landscape charac-ter. Do not create too many categories. The greater thenumber of categories, the more assessment work will

be needed to modify the protocol and the more you willbe accommodating degradation within the evaluationsystem. As an extreme example of the latter problem,you would not want to create a stream class consistingof those streams that have bank-to-bank cropping andat least one sewage outfall.

Step 3 A ssess sit es.

Assess a series of sites representing a range of condi-tions from highly impacted sites to least impacted sites.

Try to have at least 10 sites in each of your tentativeclasses. Those sites should include several potential“least impacted reference sites.” Try to use sites that

have been assessed by other assessment methods(such as sites assessed by state agencies or universi-ties). As part of the assessments, be sure to recordinformation on potential classification factors and if any particular elements are difficult to score. Takenotes so that future revisions of the elements can be re-scored without another site visit.

Step 4 Rank the s i tes.

Begin your data analysis by ranking all the sites frommost impacted to least impacted. Rank sites accordingto the independent assessment results (preferred) orby the SVAP scores. Initially, rank all of the sites in thestate data set. You will test classifications in subse-quent iterations.

Step 5 Disp lay sco r i ng da ta .Prepare a chart of the data from all sites in your state.

The columns are the sites arranged by the ranking. Therows are the assessment elements, the overall numeri-cal score, and the narrative rating. If you have inde-pendent assessment data, create a second chart byplotting the overall SVAP scores against the indepen-dent scores.

Step 6 Eval ua te responsiveness.

Does the SVAP score change in response to the condi-tion gradient represented by the different sites? Arethe individual element scores responding to key re-

source problems? Were users comfortable with allelements? If the answers are yes, do not change theelements and proceed to step 7. If the answers are no,isolate which elements are not responsive. Revise thenarrative descriptions for those elements to betterrespond to the observable conditions. Conduct a"desktop" reassessment of the sites with the newdescriptions, and return to step 4.

Step 7 Eva lua te the nar ra t i ve ra t i ng br eak -

po in ts .

Do the breakpoints for the narrative rating correspond

to other assessment results? The excellent rangeshould encompass only reference sites. If not, youshould reset the narrative rating breakpoints. Set theexcellent breakpoint based on the least impactedreference sites. You must use judgment to set theother breakpoints.

Step 8 Eval uat e tenta t i ve class i f i ca t ion sys tem.

Go back to step 4 and display your data this time bythe tentative classes (ecoregions or stream classes). Inother words, analyze sites from each ecoregion oreach stream class separately. Repeat steps 5 through 7.If the responsiveness is significantly different from the

responsiveness of the statewide data set or the break-points appear to be significantly different, adopt theclassification system and revise the protocol for eachecoregion or stream class. If not, a single statewideprotocol is adequate.


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After the initial modification of the SVAP, the statemay want to set up a process to consider future revi-sions. Field offices should be encouraged to locate andassess least impacted reference sites to build the database for interpretation and future revisions. Ancillarydata should be collected to help evaluate whether apotential reference site should be considered a refer-ence site.

Caution should be exercised when considering futurerevisions. Revisions complicate comparing SVAPscores determined before and after the implementa-tion of conservation practices if the protocol is sub-stantially revised in the intervening period. Developinginformation to support refining the SVAP can becarried out by graduate students working coopera-tively with NRCS. The Aquatic Assessment Workgrouphas been conducting a pilot Graduate Student Fellow-ship program to evaluate whether students would bewilling to work cooperatively for a small stipend. Earlyresults indicate that students can provide valuable

assistance. However, student response to advertise-ments has varied among states. If the pilot is success-ful, the program will be expanded.


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R e f e r e n c e s

Binns, N.A., and F.M. Eiserman. 1

USDA Stream Visual Assessment

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