Methods Protocol
Erosion Assessment
ENVIRONMENTAL MONITORING AND ASSESSMENT
PROGRAM-SURFACE WATERS:
FIELD OPERATIONS AND METHODS FOR MEASURING
THE ECOLOGICAL CONDITION OF WADEABLE STREAMS
As presented by James M. Lazorchak, Donald J. Klemm, and David V. Peck
Historically the protocol edited by Lazorchak, Klemm and Peck presented twelve habitat parameters to rank habitat condition: (in order parameters 1-12) in-stream cover (fish), epifaunal substrate, embeddedness, velocity/depth regimes, channel alteration, sediment deposition, frequency of riffles, channel flow status, condition of banks, bank vegetation protection, grazing or other disruptive pressure, and riparian vegetation zone with (least buffered side). The twelve habitat parameters have now been reduced to 10 and the order has changed as follows:
1. in-stream cover (fish) combined with epifaunal substrate
2. embeddedness
3. velocity/depth regimes
4. sediment deposition
5. channel flow status
6. channel alteration
7. frequency of riffles
8. condition of banks
9. bank vegetation protection
10. grazing or other disruptive pressure combined with riparian vegetation zone width
(least buffered side).
The remainder of the protocol remains the same including visual assessment methods.
*** (For full document in PDF format go to http://www.epa.gov/emap/html/pubs/docs/groupdocs/surfwatr/field/Sec14.PDF) ***
EPA/620/R-94/004F
September 1998
ENVIRONMENTAL
MONITORING AND ASSESSMENT PROGRAMSURFACE
WATERS:
FIELD OPERATIONS
AND METHODS FOR MEASURING THE
ECOLOGICAL
CONDITION OF WADEABLE STREAMS
Edited by
James M. Lazorchak 1, Donald J.
Klemm1,
and David V. Peck 2
1
Ecosystems Research
Branch
Ecological Exposure
Research Division
National Exposure
Research Laboratory
2
Regional Ecology
Branch
Western Ecology
Division
National Health and
Environmental Effects Research Laboratory
NATIONAL EXPOSURE
RESEARCH LABORATORY
OFFICE OF RESEARCH AND
DEVELOPMENT
NATIONAL HEALTH AND
ENVIRONMENTAL EFFECTS RESEARCH LABORATORY
OFFICE OF RESEARCH AND
DEVELOPMENT
SECTION 14
RAPID HABITAT AND
VISUAL STREAM ASSESSMENTS
by
James M. Lazorchak1, Alan T.
Herlihy2, and Jim Green3
After all other samples and
field data have been collected, the field team conducts an overall habitat
assessment of the stream, makes a general visual assessment of the stream, and
performs a final check of the data forms and samples before leaving the stream
site (see Section 15). The habitat assessment protocol used is adapted from
EPA's “rapid” bioassessment protocols (Plafkin et al, 1989), and has been
refined from various applications across the country. The approach focuses on
integrating information from specific parameters on the structure of the
physical habitat. The objective of the visual stream assessment is to record
field team observations of catchments and stream characteristics that are
useful for data validation, future data interpretation, ecological value
assessment, development of associations, and verification of stressor data. The
observations and impressions of field teams are extremely valuable.
1.1 RAPID HABITAT ASSESSMENT
Based on the perception
gained from collecting samples and measurements from throughout the sampling
reach, classify the stream as either “Riffle/run” or “Pool/glide” prevalent
based on your visual impression of the dominant habitat type. Choose the
prevalent habitat type based on which habitat type occupies the majority of the
length of the sampling reach. A different field data form is completed
depending upon the prevalent habitat type.
For each prevalent habitat type, twelve
characteristics (termed “parameters”) of habitat are considered and evaluated
as part of the rapid habitat assessment. These parameters are described in
Table 14-1. Most of the parameters are evaluated similarly for both types of
prevalent habitats. In four cases, the same parameter is evaluated differently,
or a different (but ecologically equivalent) parameter is evaluated in
riffle/run prevalent versus pool/glide prevalent streams. Epifaunal substrates
are evaluated differently in riffle/run and pool/glide prevalent streams.
Substrate embeddedness is evaluated in riffle/run prevalent streams, while pool
substrate composition is evaluated in pool/glide prevalent streams. The
presence of four potential types of microhabitat types based on combinations of
depth and current velocity is evaluated in riffle/run prevalent streams, while
the presence of four potential types of pool microhabitat based on depth and
area are evaluated in pool/glide prevalent streams. The frequency of riffles is
evaluated in riffle/run prevalent streams, while channel sinuosity is evaluated
in pool/glide prevalent streams.
The procedure for
conducting the rapid habitat assessment is presented in Table 14-2. For each of
the twelve parameters, rate the overall quality of the sampling reach on a
scale of 0 to 20. For riffle/run prevalent streams, record your scores for each
parameter on the riffle/run version of the Rapid Habitat Assessment Form as
shown in Figures 14-1 and 14-2. If the stream is classified as a pool/glide
prevalent stream, record your scores for each parameter on the pool/glide
version of the Rapid Habitat Assessment Form as shown in Figures 14-3 and 14-4.
Transfer the scores assigned for each parameter to the box in the left-hand
column of the form. Sum the scores for each parameter and record the total
score in the box at the top of page 1 of the form.
14.2 VISUAL STREAM ASSESSMENTS
The objective of the visual
stream assessment is to record field crew observations of catchments/stream
characteristics useful for future data interpretation, ecological value
assessment, development of associations, and verification of stressor data.
Observations and impressions of field crews are extremely valuable. Thus, it is
important that these observations about stream characteristics be recorded for
future data interpretation and validation. The assessment form is designed as a
template for recording pertinent field observations. It is by no means
comprehensive and any additional observations should be recorded in the
Comments section of the form.
Complete the assessment
form after all other sampling and measurement activities have been completed.
Take into account all observations the sampling team has made while at the
site. The assessment includes the following components: watershed activities
and
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TABLE 14-1.
DESCRIPTIONS OF HABITAT PARAMETERS USED IN THE RAPID ASSESSMENT OF
STREAMS |
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|
Habitat Parameter |
Prevalent Habitat Type R=Riffle/run P=Pool/glide |
Description and
Rationale |
|
|
1. Instream Cover (fish) |
R P |
Includes the relative quantity and variety of natural
structures in the stream (e.g., fallen trees, logs, and branches, large
rocks, and undercut banks) that are available for refugia, feeding, or
spawning. A wide variety of submerged structures in the stream provide fish
with a large number of niches, thus increasing assemblage diversity. |
|
|
2. Epifaunal Substrate (benthic invertebrates) |
R |
Essentially the amount of niche space or hard
substrates (rocks, snags) available for insects and snails. Numerous types of
insect larvae attach themselves to rocks, logs, branches, or other submerged
substrates. As with fish, the greater the variety and number of available
niches or attachments, the greater the variety of insects in the stream.
Rocky-bottom areas are critical for maintaining a healthy variety of insects
in most high gradient streams. |
|
|
P |
The abundance, distribution, and quality of substrate
and other stable colonizing surfaces (e.g., old logs, snags, aquatic
vegetation) that maximize the potential for colonization. |
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3A. Embeddedness |
R |
The extent to which rocks (gravel, cobble, and
boulders) are covered or sunken into the silt, sand, or mud of the stream
bottom. Generally, as rocks become embedded, the surface area available to
macroinvertebrates and fish for shelter, spawning, and egg incubation is
decreased. To estimate the percent of embeddedness, observe the amount of
silt or finer sediments overlying and surrounding the rocks. If kicking does
not dislodge the rocks or cobble, they may be greatly embedded. It is useful
to observe the extent of the dark area on their underside of a few rocks. |
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|
3B. Pool Substrate Characterization |
P |
Evaluates the type and condition of bottom substrates
found in pools. Firmer sediment types (e.g., gravel, sand) and rooted aquatic
plants support a wider variety of organisms than a pool substrate dominated
by mud or bedrock and no plants. In addition, a stream that has a uniform
substrate in its pools will support far fewer types of organisms than a
stream that has a variety of substrate types. |
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|
4A. Velocity and Depth Regimes |
R |
There are four primary current and depth combinations:
(1) slow-deep, (2) slow shallow, (3) fast-deep, and (4) fast-shallow. The
best streams in high gradient regions will have all four combinations
present. The presence or availability of these four habitats relates to the
ability of the stream to provide and maintain a stable aquatic environment.
In general use a depth of 0.5 m to separate shallow from deep and a current
velocity of 0.3 m/sec to separate fast from slow. |
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4B. Pool Variability |
P |
Rates the overall mixture of pool types found in streams,
according to size and depth. The four basic types of pools are large-shallow,
large-deep, small-shallow, and small-deep. A stream with many pool types will
support a wide variety of aquatic species. Rivers with low sinuosity (few
bends) and monotonous pool characteristics do not have sufficient quantities
and types of habitat to support a diverse aquatic community. As a general
guideline, consider a pool deep if it is greater than 1 m deep, and large if
its length, width, or oblique dimension is greater than half the stream
width. |
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|
5. Channel Alteration |
R P |
Basically a measure of large-scale changes in the
shape of the stream channel. Many streams in urban and agricultural areas
have been straightened, deepened, or diverted into concrete channels, often
for flood control purposes. Such streams have far fewer natural habitats for
fish, macroinvertebrates, and plants than do naturally meandering streams.
Channel alteration is present when the stream runs through a concrete
channel; when artificial embankments, riprap, and other forms of artificial
bank stabilization or structures are present; when the stream is very
straight for significant distances; when dams and bridges are present; and
when other such changes have occurred. |
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TABLE 14-1
(Continued) |
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Habitat Parameter |
Prevalent Habitat Type R=Riffle/run P=Pool/glide |
Description and
Rationale |
|
|
6. Sediment Deposition |
R P |
The amount of sediment that has accumulated and the
changes that have occurred to the stream bottom as a result of the
deposition. Deposition occurs from large-scale movement of sediment caused by
watershed erosion. Sediment deposition may cause the formation of islands,
point bars (areas of increased deposition usually at the beginning of
meanders that increase in size as the channel is diverted toward the outer
bank) or shoals or result in the filling of pools. Increased sedimentation
also results in increased deposition. Usually this is evident in areas that
are obstructed by natural or man-made debris and areas where the stream flow decreases,
such as bends. High levels of sediment deposition create an unstable and
continually changing environment that becomes unsuitable for many organisms. |
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7A. Frequency of Riffles |
R |
The sequence of riffles occurring in a stream.
Riffles are a source of high-quality habitat and diverse fauna; therefore, an
increased frequency of occurrence greatly enhances the diversity of the
stream community. For areas where riffles are uncommon, a run/bend ratio can
be used as a measure of sinuosity. A large degree of sinuosity provides for
diverse habitat and fauna, and the stream is better able to handle the high
energy flows that result from storms than are relatively straight streams. |
|
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7B. Channel Sinuosity |
P |
Evaluates the meandering or relative frequency of bends
of the stream. Streams that meander provide a variety of habitats for aquatic
organisms, whereas straight stream segments are characterized by monotonous
habitats that are prone to flooding. A high degree of sinuosity creates a
variety of pools and reduces the energy from surges when the stream flow
fluctuates. The absorption of this energy by bends protects the stream from
excessive erosion and flooding. In "oxbow" streams of coastal areas
and deltas, meanders are highly exaggerated and transient. Natural conditions
are shifting channels and bends. Alteration of these streams is usually in
the form of flow regulation and diversion. |
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8. Channel Flow Status |
R P |
The degree to which the channel is filled with water.
The flow status will change as the channel enlarges or as flow decreases as a
result of dams and other obstructions, diversions for irrigation, or drought.
When water does not cover much of the streambed, the amount of useable
substrate for aquatic organisms is limited. |
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9. Condition of Banks |
R P |
The stream banks are eroded (or have the potential
for erosion). Steep banks are more likely to collapse and suffer from erosion than
are gently sloping banks and are therefore considered to be unstable. Signs of
erosion include crumbling, unvegetated banks, exposed tree roots, and exposed
soil |
|
|
10. Bank Vegetative Protection |
R P |
The amount of the stream bank that is covered by
vegetation. The root systems of plants growing on stream banks help hold soil
in place, thereby reducing the amount of erosion that is likely to occur.
This parameter supplies information on the ability of the bank to resist
erosion, as well as some additional information on the uptake of nutrients by
the plants, the control on instream scouring, and stream shading. Banks that
have full, natural plant growth are better for fish and macroinvertebrates
than are banks without vegetative protection or those shored up with concrete
or riprap. |
|
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11. Grazing or Disruptive Pressure |
R P |
Disruptive changes to the riparian zone because of grazing
or human interference (e.g., mowing). In areas of high grazing pressure from
livestock or where residential and urban development activities disrupt the
riparian zone, the growth of a natural plant community is impeded.
Residential developments, urban centers, golf courses, and rangeland are the
common causes of anthropogenic effects on the riparian zone. |
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12. Riparian Vegetated Zone Width |
R P |
The width of natural vegetation from the edge of the
stream bank (riparian buffer zone). The riparian vegetative zone serves as a
buffer zone to pollutants entering a stream from runoff, controls erosion,
and provides stream habitat and nutrient input into the stream. A relatively
undisturbed riparian zone reflects a healthy stream system; narrow, far less
useful riparian zones occur when roads, parking lots, fields, lawns, bare
soil, rocks, or buildings are near the stream bank. The presence of "old
fields" (i.e., a previously developed field allowed to convert to
natural conditions) will rate higher than fields in continuous or periodic
use. Paths and walkways in an otherwise undisturbed riparian zone may be
judged to be inconsequential to destruction of the riparian zone. |
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TABLE 14-2.
PROCEDURE FOR CONDUCTING THE RAPID HABITAT ASSESSMENT |
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1. Based on observations
during previous sample collection and field measurement activities, classify
the sampling reach as predominantly
flowing water habitat (“Riffle/run”) or slow water habitat (“Pool/glide”). 2. Select the
appropriate version of the Rapid Habitat Assessment Form (“Riffle/Run
Prevalence” or “Pool/Glide Prevalence”) based on the classification in Step
1. 3. For each
of the 12 habitat parameters, determine the general “quality” category (“POOR”, “MARGINAL”, “SUB-OPTIMAL”, or “OPTIMAL”) of the
entire sampling reach. Assign and circle a score from the values available
within each quality category. For each parameter, the sampling reach can be
scored from 0 (worst) to 20 (best). 4. After the
sampling reach has been scored for all parameters, transfer the score circled
for each category to the corresponding “SCORE” boxes in the “HABITAT PARAMETER”
column of the assessment form. 5. Sum the
scores recorded in Step 4 over all 12 habitat parameters. Record the total
score for the sampling reach in the “TOTAL SCORE” box on page 1 of the
assessment form. The total score can range from 0 to 240. |
observed disturbances, reach characteristics, water
body character, general assessment, and local anecdotal information. The
procedure for conducting the visual assessment of the sampling reach is
presented in Table 14-3. Record data and observations for each component of the
assessment on the Assessment Form as shown in Figures 14-5 and 14-6.
Each watershed activity or
disturbance is rated into one of four categories of abundance or influence: not
observed, low, medium, or high. Leave the line blank for any activity or
disturbance type not observed. The distinction between low, medium, and high
will be subjective. For example, if there are 2-3 houses on a stream, the
rating for “Houses” would be low. If the stream is in a suburban housing
development, rate it as high. Similarly, a small patch of clear cut logging on
a hill overlooking the stream would be rated as low. Logging activity right on
the stream shore, however, would be rated as high.
When assessing reach
characteristics, make your best estimate as to the percent of the sampling
reach (40 channel widths) that had each type of listed riparian zone land use
immediately adjacent to the stream. Also rate the water clarity, including
whether you believe the clarity is influenced by recent storm events (see
Section 4). Water body character is defined as "the physical habitat
integrity of the water body, largely a function of riparian and littoral
habitat structure, volume change, trash, turbidity, slicks, scums, color, and
odor.” Water body character is assessed using two attributes, the degree of
human development, and aesthetics. Rate each of these attributes on a scale of
1 to 5. For development, give the stream a "5" rating if it is
pristine, with no signs of any human development. A rating of "1"
indicates a stream which is totally developed (e.g., the entire stream is lined
with houses, or the riparian zone has been removed). For aesthetics, base your
decision on any factor about the stream that bothers you (e.g., trash, algal
growth, weed abundance, overcrowding).
The general assessment
component includes any observations that will help in data interpretation in
the pertinent section. General assessment comments can include comments on
wildlife observed, diversity of terrestrial vegetation, age class of forest, or
any other observation. Comments from locals are often useful and should be
recorded in the “LOCAL ANECDOTAL INFORMATION” section. The back side of the form (Figure 14-6) is
available for general comments.
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TABLE 14-3.
PROCEDURE FOR CONDUCTING THE FINAL VISUAL ASSESSMENT OF A STREAM |
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1. After all other sampling and measurement
activities are completed; fill out the header section of an Assessment Form.
Use your perceptions obtained during the course of the day, while at the
stream or driving/walking through the catchment to complete the remainder of
the form. 2. WATERSHED ACTIVITIES AND DISTURBANCES OBSERVED: Rate each type of activity or disturbance listed
on the form as either “Not observed”, “Low”, “Medium”, or “High”, and record
the rating on the Assessment Form. Keep in mind that ratings will be somewhat
subjective and that an extensive effort to quantify the presence and
intensity of each type of stressor is not required. General categories of
activities and types of disturbance are described below: • Residential: The presence of any of the
listed disturbances adjacent to or near the stream. • Recreational: The presence of organized
public or private parks, campgrounds, beaches or other recreation areas
around the stream. If there are signs of informal areas of camping, swimming
or boating around the stream (e.g., swimming hole), record them as
"primitive" parks, camping. • Agriculture: The presence of cropland,
pasture, orchards, poultry, and/or livestock. • Industrial: Any industrial activity (e.g.,
canning, chemical, pulp), commercial activity (stores, businesses) or
logging/mining activities around the stream or in the catchment. Describe in more
detail in the comments section. • Management: Any evidence of liming
activity, water treatment, dredging or channelization, flow control
structures, etc. Any oddities or further elaboration should be
recorded in the Comments section. 3. REACH CHARACTERISTICS: For each type of riparian vegetation cover or land
use category listed on the Assessment Form, estimate the proportion of the
sampling reach immediately adjacent to the stream that is affected. Place and
“X” in the appropriate extent class box (Rare [< 5%], Sparse [5 to 25%],
Moderate [25 to 75%], and Extensive [> 75%]) on the form. 4. Classify the overall water clarity within the
sampling reach as clear, murky, or highly turbid. Place an “X” in the
appropriate box on the “WATER CLARITY” line of the Assessment Form. If you believe that
water clarity has been influenced by a recent storm event, also place an “X”
in the “STORM INFLUENCED” box. 5. WATER BODY CHARACTER: Assign a rating of 1 (highly disturbed) to 5
(pristine) based on your general impression of the intensity of impact from
human disturbance. Place an “X” in the box next to the assigned rating on the
Assessment Form. Assign a rating to the stream based on overall aesthetic
quality, based on your opinion of how suitable the stream water is for
recreation and aesthetic enjoyment today. Place and “X” in the box next to
the assigned rating on the Assessment Form. 5.
Beautiful, could not be any nicer. 4.
Very minor aesthetic problems; excellent for swimming, boating, enjoyment. 3.
Enjoyment impaired. 2.
Level of enjoyment substantially reduced. 1.
Enjoyment nearly impossible. Add any comments you feel might aid data
interpretation in the Comments Section. 6. GENERAL ASSESSMENT: record comments on wildlife observed, perceived
diversity of terrestrial vegetation, and the estimated age class of forest (0
to 25 yr, 25 to 75 yr, or > 75 yr.) on the Assessment Form. 7. LOCAL ANECDOTAL INFORMATION: Record any information regarding the past or
present characteristics or condition of the stream provided by local
residents. |
Appendix II
1. Description of Habitat Parameters
2. Habitat Assessment Field Data Sheet
3. Standardized Erosion Form
4. Standardized Bank Erosion Potential
Form
Habitat Assessment Field
Data Sheet
Standardized Erosion
Data Sheets
Standardized Bank
Erosion Potential
Standardized Erosion
Data Sheet
