v>EPA
United States
Environmental Protection
Agency
Environmental Research
Laboratory
Corvallis OR 97333
EPA-600/S3-82-002 August 1982
Project Summary
A Review of Aquatic
Habitat Assessment Methods
Gerald S. Schuytema
This project was an extensive literature
review of aquatic habitat assessment
techniques. The objective was to help
water quality investigators and natural
resource managers unfamiliar with such
techniques to become aware of the
methods and current trends in develop-
ment, and to aid in deciding what tech-
niques might best fit project goals.
Approximately 30 methods were sum-
marized and compared.
Most methods have been developed
by Federal or state agencies and have
had the greatest application in the west-
ern United States. They are classified
here according to a number of mutually
interacting categories such as project
impact, inventory and general descrip-
tion, stream type, particular fish species
orientation, and channel stability. Many
of the methods have developed indices
or numerical values which can be used
for comparisons or evaluation. The U.S.
Fish and Wildlife Service is channeling
substantial effort into the development
of habitat evaluation procedures (HEP),
techniques designed for assessing pro-
ject impacts oriented toward a particular
species of interest.
Parameters most frequently considered
in the reviewed methods have included
flow, temperature, water surface, width,
turbidity, gradient, velocity, depth, bank
stability measures, bottom size distribu-
tion, siltation, cover, pool size, attached
vegetation, fish and invertebrate types,
riparian zone vegetation and shade, and
obstructing factors such as waterfalls,
dams, and culverts.
While many methods, are similarly
based on such parameters as substrate,
cover, flow, depth, and stream and flood-
plain morphology, they still vary in effort
required and objectives. Thus, the ulti-
mate choice of methods for any purpose
including nonpoint source pollution eval-
uation depends on geographical location,
stream type, investigator expertise,
economics, and precise project goals.
This Project Summary was developed
by EPA's Environmental Research Labo-
ratory, Corvallis, OR, to announce key
findings of the research project that is
fully documented In a separate report of
the same title (see Project Report ordering
information at back).
Introduction
Habitat assessment has long been rec-
ognized by natural resource agencies as
an essential task in the management and
preservation of fish and wildlife. Water
quality agencies are beginning to realize
that measuring characteristics of the
water column is insufficient to predict
the biological condition of a stream sys-
tem because of changes that can also
occur in the quality of the physical envi-
ronment from land use impacts. Flow,
water quality, habitat structure, and
energy source are all important variables
affecting biological integrity. Activities
such as urbanization, agriculture, silvicul-
ture, mining, construction, land disposal,
and hydrologic modifications often have
severe impacts on physical habitat quality.
There are few compilations of the di-
verse and scattered literature on aquatic
habitat assessment. This review includes
approximately 30 methods, many inter-
related, located in a literature base formed
in large measure by state and Federal
agency reports. While these methods
are generally divided into categories
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based on stream type (salmonid and non-
salmonid), purpose (impact assessment
and general inventory) or technical ap-
proach, actual differences between
many are slight.
This compilation will help water quality
investigators and natural resource man-
agers unfamiliar with aquatic habitat
assessment techniques to become aware
of sources and apparent trends in devel-
opment, and to decide what techniques
might best fit project goals.
Discussion
Many of the reviewed techniques are
still under development, several are rep-
resented in a series of reports or publica-
tions, and some are unpublished. Federal
agencies (U.S. Forest Service, U.S. Fish
and Wildlife Service, U.S. Bureau of Land
Management, U.S. Soil Conservation
Service) have been responsible for the
majority of the methods, and state agen-
cies (Departments of Fish, Game, Con-
servation, Natural Resources, Wildlife)
and interagency groups account for the
remainder. Primary emphasis on methods
development has been in the West.
The methods are classified into a
variety of groups depending upon their
intended purposes, stream types, and
technical approaches. These groups are
not necessarily mutually exclusive, as a
given method can be represented in sev-
eral categories or apply to a number of
situations. For instance, while most of
the reviewed methods (25) appear to be
used in salmonid streams, six are also
used in non-salmonid streams. Only two
of the methods are used primarily in non-
salmonid streams.
The methods can also be categorized
according to purpose. Impact assessment
techniques are used primarily to evaluate
the impact of water and land resource
development projects, construction,
and alterations due to human activity,
differing flow regimes, and pollution.
General description or inventory methods
are primarily used for fisheries, water
and land use planning and management,
habitat research, baseline data inven-
tories, and environmental statements.
Some of the salmonid stream methods
are based in part on the U.S. Forest Ser-
vice (USFS) Stream Reach Inventory and
Channel Stability Evaluation. This method
was developed to systemize evaluations
of the resistive capacity of mountain
stream channels to bed and bank mate-
rial detachment. Adding factors related
specifically to aquatic organism habitat
allows this approach to be used as a
habitat assessment technique.
Some of the groups also contain index
and transect aspects. Index or numerical
values facilitate comparisons or judg-
ments between stations or locations; all
major method groups contain some index
producing techniques. Transect methods
are based upon sampling a transect
across the stream in contrast to sam-
pling a stream reach of particular length.
Only Federal agencies seem to have
emphasized this, type of approach.
The major habitat parameters and
related factors used or evaluated in the
various types of methods are grouped in
Table 1. The groups (surrounding area,
riparian zone, general descriptors, stream
banks, stream bottom, fish habitat,
characteristics, and biology), are each
presented with a percentage indicating
the relative number of reviewed methods
using the parameters within a group.
Individual parameters are listed accord-
ing to predominance of use.
Habitat parameters associated with
surrounding stream areas are empha-
sized by topographical and geographical
features and land use of the surrounding
and upstream areas. A more closely
associated area, the riparian zone, gives
primary importance to vegetative type,
shading effect, and streamside cover.
Most of the methods use a large variety
of descriptive terms to characterize
habitat. Some of the more important in-
clude flow, temperature, width, velocity,
gradient, turbidity, and depth.
Many methods stress various aspects
of fish habitat, with instream cover and
the number and size of pools ranking
highest. .Obstructions to fish migration
are primarily characterized by culverts,
dams, and debris piles. Nonphysical fac-
tors associated with habitat analysis
include features such as attached algae
and macrophytes, fish species, size,
weight and abundance.
This review represents the status of
assessment methods at a point in time
and will become quickly outdated as
new methods develop and older ones are
revised. The grouping of the techniques
as reviewed are but one way of examining
them; other logical arrangements may
become apparent with further additions
and refinements. The purpose for which
a method was intended or the basic phi-
losophy of its development seem to be
most important in determining its place
in some sort of classification scheme.
The methods were classified in the
review on the basis of stream type (sal-
monid, non-salmonid or both combined)
primarily to allow potential users to
become aware of methods in their own
areas of interest. There is little upon
which to differentiate these methods,
however, based on the type of param-
eters examined. In fact, a method used
for non-salmonid habitat was developed
for salmonid streams. Some differences
between these methods are: 1) less
emphasis on surrounding area, riparian
zone, stream banks, and fish habitat-
related parameters in salmonid stream
methods, and 2) less emphasis on
stream banks by combination methods.
Validation is one of the most important
aspects confronting management's deci-
sion on assessment technique selection.
The lack of comparative studies to deter-
mine if different methods provide similar
results using the same data base has
been emphasized. The system that in-
corporates the best available data and
that is the least subjective should be the
most accurate, but that question will not
be resolved until enough systems have
been compared and sufficient replicated
validations made.
The results of a survey of 40 state
agencies indicate that very few have
developed or used a habitat assessment
technique specifically for non-point source
pollution investigations, even though a
majority of those queried did acknowl-
edge the desirability of such techniques.
The States of Oregon and Washington
both use techniques based on channel
stability with additional biotic variables.
The State of Wisconsin uses a biotic in-
dex; this system, however, is not based
on physical parameters. North Carolina
uses a similar non-physical stream
assessment system. South Dakota uses
a general habitat assessment technique
to inventory trout habitats in watersheds
affected by road and railroad construc-
tion, timber management, agricultural
practices, mining and flood control
projects.
Conclusions and
Recommendations
Some representative methods which
are worthy of consideration in selecting
a technique include: 1) methods based
on U.S. Forest Service Channel Stability
Methods with added factors of particular
concern to salmonids;1 2) a general sal-
monid stream method with warm water
stream potential which emphasizes
computer storage, data manipulation,
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Table 1.
Habitat Parameters and Related Factors Evaluated in the Reviewed Methods1
Surrounding Area (26%)2
surrounding land use
topography/geography
upstream land use
historical land use
flood plain condition
urbanization
Riparian Zone (78%)
vegetation species/type
percent shade
streamside cover
vegetation size
vegetation density
width of zone
ungulate grazing/damage
flood plain width
vegetation successional stage
General Descriptors (10%)
flow
water temperature
water surface width
color/turbidity/transparency
gradient
velocity
average depth
air temperature
channel width
length of segment
elevation
pool/riffle ratio
stream order
stage/level
stream length
channel type/configuration
tributaries/tributary of sinuosity
pollution sources
bottom composition—general
valley bottom width
valley type/configuration
weather
drainage area
watershed type
water source(s)
water use
percent channelized
stream area
direction of flow
Stream Banks (57%)
bank stability
landform slope
mass wasting
debris jam potential
vegetative bank protection
channel capacity
bank rock content
obstructions
cutting
deposition
percent erosion/bare soil
height banks
percent damage
percent grazing
Stream Bottom (86%)
bottom size distribution
siltation/sedimentation
consolidation/particle packing
rock angularity
brightness
scouring/deposition
inbeddedness
percent channel movement
roughness coefficient
Fish Habitat (75%)
instream cover
pool length/width
pools number/percent
riffle width
pool depth
spawning gravel abundance/volume
pool area
spawning gravel quality
riffle depth
riffles percent
spawning gravel size
runs percent
nursery habitat
riffle velocity
runs width
runs depth
runs velocity
Biology (86%)
attached algae/macrophytes
fish species
invertebrate type/species
invertebrate abundance/rank
fish size/weight
fish abundance
invertebrate diversity
Obstructions (45%)
waterfalls
beaver dams/dams
culverts
debris piles/slides
log jams
channelization
dredging
impoundments
levies/dikes
riprap
1 Rated according to predominance of use within each group.
2 Percent of methods using parameters in each group.
transect sampling, and index value of
optimum habitat;2 3) a method orien-
tated toward chosen species of interest
and designed to demonstrate the impact
of any given flow regime on fish habitat
potential in all stream types;3 4) a
method appropriate to large projects in
all stream types and orientated toward
chosen species of interest (uses a habitat
suitability index value where selected
parameters are measured and compared
with habitat requirements as indicated
by response curves);4 and 5) a supple-
mental salmonid stream method based
only on substrate and survival-to-emer-
gence relationships.5
The development of habitat assessment
procedures has progressed from simple
surveys, many designed for inventory,
and from simple index type rating sys-
tems to more complex, often species-
orientated systems, frequently assisted
by computerized information storage
and retrieval. This increased develop-
> US GOVERNMENT PRINTING OFFICE 1982-559-017/0783
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ment is a reflection of the recognition of
the importance and usefulness of aquatic
habitat in stream baseline and impact
assessment. Many governmental agen-
cies are presently developing techniques
applicable to their own needs. The trend
in method development is toward sys-
tems that recognize habitat potential as
valuable in the definition of baseline con-
ditions or in impact evaluation. Comparing
a stream's condition to its own potential
is a large step forward in understanding
perturbation effects.
A universal habitat technique is prob-
ably not realistic because of the diversity
of watershed and stream types, but a
number of methods have the potential,
with regional adaptations, to be used
over wide areas. The development of a
technique applicable only to a certain
type of pollutant or impact is also imprac-
tical, but the selection of a method which
objectively measures the impact upon a
stream parameter of interest can be
useful. The development of method cri-
teria applicable to non-salmonid streams
would be of great benefit to lowland
watershed and resource managers.
Diverse interests and goals in different
Federal and state agencies concerned
with the enforcement of water quality
standards, detection, and documentation
of pollution, protection of the natural
environment, and management of natural
resources has led naturally to the devel-
opment of different types or views of
habitat assessment techniques. Increased
cooperation between agencies and in-
creased awareness of new techniques
can do much to promote the use and im-
provement of habitat technology. The
ultimate choice of an aquatic habitat
method, however, may hinge upon
economics, expertise, and project goals.
References
1. Rickert, D.A., G.L. Beach, J.E. Jack-
son, D.M. Anderson, H. Halen, and E.
Suwijn. 1978. Oregon's procedure
for assessing the impacts of land
management activities on erosion re-
lated non-point source problems.
Oregon Dept. Environ. Quality,
Portland. 219 p.
2. Dunham, O.K. and A.W. Collotzi.
1975. The transect method of stream
habitat inventory. U.S. For. Serv.,
Intermountain Region, Ogden, Utah.
98 p.
3. Stalnaker, C.B. 1978. The IFG incre-
mental methodology for physical
stream habitat evaluation, pp. 126-
135. In: Surface Mining and Fish/
Wildlife Needs in the Eastern United
States. Samuel, D.E., J.M. Stauffer,
C.H. Hocutt, and W.T. Mason, eds.
U.S. Fish and Wildlf. Serv., FWS/
OBS-78/81.
4. U.S. Fish and Wildlife Service. 1981.
The habitat evaluation procedure.
Div. of Ecol. Ser. 102 ESM. n.p.
5. Lotspeich, F.R. and F.H. Everest.
1981. A new method for reporting
and interpreting textural composition
of spawning grounds. U.S. For. Ser.
Res. Note. PNW-369. 11 p.
The EPA author Gerald S. Schuytema (also the EPA Project Officer, see below)
is with the Environmental Research Laboratory, Corvallis, OR 97333.
The complete report, entitled "A Review of Aquatic Habitat Assessment
Methods." (Order No. PB 82-189 648; Cost: $7.50, subjectto change) will be
available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Environmental Research Laboratory
U.S. Environmental Protection Agency
Corvallis. OR 97333
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Postage and
Fees Paid
Environmental
Protection
Agency
EPA 335
Official Business
Penalty for Private Use $300
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