SEPA
United States
Environmental Protection
Agency
Environmental Research
Laboratory
Corvallis OR 97330
EPA-600/3-79-014
February 1979
Research and Development
Monitoring
Spawning Gravel in
Managed Forested
Watersheds
A Proposed
Procedure
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ECOLOGICAL RESEARCH series. This series
describes research on the effects of pollution on humans, plant and animal spe-
cies, and materials. Problems are assessed for their long- and short-term influ-
ences. Investigations include formation, transport, and pathway studies to deter-
mine the fate of pollutants and their effects This work provides the technical basis
for setting standards to minimize undesirable changes in living organisms in the
aquatic, terrestrial, and atmospheric environments.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/3-79-014
February 1979
MONITORING SPAWNING GRAVEL IN
MANAGED FORESTED WATERSHEDS
A Proposed Procedure
by
M. A. Shirazi and D. H. Lewis
Ecosystems Modeling and Analysis Branch
Corvallis Environmental Research Laboratory
Corvallis, Oregon 97330
and
W. K. Seim
Department of Fisheries and Wildlife
Oregon State University
Corvallis, Oregon 97331
Report originally prepared for EPA Region X
Robert Rulifson, Project Officer
CORVALLIS ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CORVALLIS, OREGON 97330
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DISCLAIMER
This report has been reviewed by the Corvallis Environmental Research
Laboratory, U.S. Environmental Protection Agency, and approved for
publication. Mention of trade names or commercial products does not
constitute endorsement or recommendation for use.
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FOREWORD
Effective regulatory and enforcement actions by the Environmental Protection
Agency would be virtually impossible without sound scientific data on pollu-
tants and their impact on environmental stability and human health. Respon-
sibility for building this data base has been assigned to EPA's Office of
Research and Development and its 15 major field installations, one of which
is the Corvallis Environmental Research Laboratory (CERL).
The primary mission of the Con/all is Laboratory is research on the effects
of environmental pollutants on terrestrial, freshwater, and marine ecosystems;
the behavior, effects and control of pollutants in lake systems; and the de-
velopment of predictive models on the movement of pollutants in the biosphere.
This report proposes procedures which can be used to monitor the effects
of watershed manipulations on spawning gravels of salmonid fishes.
iii
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CONTENTS
1. Objective 1
2. Site Selection and General Survey 1
3. Number of Samples 2
4. Time and Frequency of Sampling 3
5. Methods Used for Obtaining Gravel Samples 3
6. Size of Gravel Samples 6
7. Analysis of Gravel—Wet Sieving 8
8. Analysis and Presentation of Results 9
9. Additional Data- - - 9
10. Estimating Localized and Stream-wide Impacts 10
11. Conclusions and Recommendations 12
12. References — 13
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1. OBJECTIVE
Silvlcultural activities in the Pacific Northwest introduce various
levels of sediments and debris into streams, often degrading spawning habitats
of salmonid fishes. In these mountain streams spawning takes place in riffles
where the water velocity is usually 1.5 to 2.5 ft/sec and water is 6 to 36
inches deep. The substrate in these riffles are ideal habitats for aquatic
insects which in turn respond adversely to excessive sedimentation. For these
reasons, the study of spawning habitats could provide a relatively simple and
sensitive indicator of watershed management impacts.
Simple but reliable procedures are needed to monitor spawning substrate
to assess the level of these impacts. This paper presents a preliminary
rationale for conducting a monitoring program to assess the impact of water-
shed management activities on stream spawning habitats; both on individual
spawning sites as well as for the entire stream.
There are many problems in developing a program that is simple yet reli-
able under varied conditions. A major difficulty is the absence of comprehen-
sive and reliable historical data that document these types of impacts. It is
hoped that the procedure outlined here will provide the groundwork for a
serious effort in compiling a comprehensive data base to simplify future
studies and increase their reliability.
2- Site Selection
The primary requirement for stream site selection is that the gravel
must have been used by fish for spawning. This information is usually
available from the State's Regional Fisheries Biologist. Since most monitoring
work must be done during low flow periods, the knowledge that the area has
been used for spawning eliminates the need to forecast appropriate flow level
and water velocity requirements during and after spawning at a given site.
Once a site is selected, the areal extent and the quality of the spawning
gravel must be determined. Numerous approaches have been made. For example,
Platts (1974) established monitoring transects across the stream at equally
spaced distances along a spawning area. He then selected two or more samples
along these fixed transects, identifying those samples that were within redds
or in non-redd areas. Corley (1978) selected a parcel of gravel, about 25 by
25 feet in a spawning area. Then he randomly picked several gravel samples
from within this area for analysis. Koski (1966) conducted gravel analyses
from samples taken within actual redds.
After analyzing results from these investigations it appears that reason-
able balance can be achieved between an acceptable reliability and minimum
number of samples by (a) estimating the area of the gravel in the site that is
potentially usable by fish and (b) within this area, selecting representative
samples to provide a quantitative measure of the range of conditions and thus
the quality of the gravel. This proposed procedure will be discussed in the
remainder of this paper.
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The exact boundary of the spawning gravel is difficult to identify with
precision. The gravel may be patchy, interspersed with boulders, gravel spots
and sandy spots. As an extreme example, if the flow conditions are suitable,
a steel head trout might be able to dig a redd in an area as small as 1 by 3
feet. Under more ideal conditions the spawning gravel would be as wide as
half the width of the riffle or even extending along the entire stream width.
The gravel patch can be as long, even many times longer than it is wide. It
is normally uniform in composition which simplifies identification.
Once the approximate boundaries of the gravel areas are identified within
a^riffle, the total usable area should be estimated with no particular atten-
tion to patch geometry or distribution within the riffle.
For the purpose of monitoring possible impacts of logging, road construc-
tion, etc., several gravel areas both upstream and downstream from anticipated
impact areas should be surveyed. Changes in the magnitude and gravel quality
of these areas can be used systematically to record impact.
After a heavy storm, gravel bars and patches shift, shrink or expand and
change composition. When assessing cultural impacts, results must be interpre-
ted with caution and reliability in separating the natural from cultural
events must not be anticipated. This interpretation is critical since it
determines the level of accuracy and more important, the amount of effort that
must be devoted to the task. It is at best an order of magnitude analysis,
distinguishing only the major impacts. More subtle impacts may be detected
only with an extensive data base.
3. Number of Samples Within Each Site
Analysis of large quantities of data from Platts (1967, 1972), Koski
(1966) and Corely (1978) presents a convincing argument that sampling of
gravel cannot and should not become a purely statistical exercise. Koski
(1966) studied numerous Coho salmon redds and analyzed three gravel samples
within each redd. He found a two-fold variation in the geometric mean
diameter (this measure is discussed in Section 8). Corley (1978) analyzed
hundreds of samples, five from within each 25 by 25 foot gravel patch. He
also showed a two-fold variation in the geometric mean diameter. Platts
(1974) analyzed hundreds of gravel samples for a decade along the entire South
Fork'of Idaho's Salmon River spawning areas. Again, the geometric mean dia-
meter exhibited approximately a two-fold variation. The methods used by these
authors were all different, but their data reveal that salmon tolerate and
select a range of gravel composition within each spawning site. When measured
in terms of geometric mean diameter, it is a rather wide range when viewed
from the standpoint of attaining sampling accuracy. Thus, for monitoring
purposes, it does not appear necessary to strive for extreme accuracies in
characterizing'the gravel composition. Clearly, there is no need to compli-
cate an already difficult sampling problem, knowing there is no additional
gain. Only the range of possible composition within each site is needed.
This can be obtained by visual inspection. For example, within each spawning
area, select three spots which appear coarse, fine and intermediate. Data
analysis will indicate if the selections are reasonable. Initially, it may
be desirable to duplicate the samples and document visual observation with
photographs to check against the gravel analysis.
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On-site analysis of the gravel (see Section 11) will reinforce this
learning process. The major difficulty lies in judging the gravel composition
visually as "coarse", "fine", etc., because of the underlying layers. As
samples are taken at each site, this problem is reduced but serious attempts
must be made to reinforce initial judgement with experience. It is only than
that a purely mechanical approach becomes a simple reliable field technique.
An example showing the feasibility of the visual technique is shown in
Figure 1. These sites of increasing coarseness were selected visually (site
A, coarse, site B, medium, site C, fine) from a known spawning area on Canal
Creek, a small stream in the Oregon Coast Range. Samples were taken at each
of these sites and particle size distributions were determined. As Figure 1
shows, these particle size distributions substantiate the judgements which
were made visually in the field.
The concept behind visual observation is to develop an estimation
process with a small margin of error. This means integrating all information
possible concerning the extremes of coarse and fine compositions of the spawn-
able gravel while in the field. This includes information gained as one
actually collects the samples.
4. Time and Frequency of Sampling
The requirements for good gravel conditions are critical at the final
stages of salmonid egg maturation where oxygen consumption is greatest.
Another critical period is during emergence. It would be ideal to sample as
soon as possible after egg emergence to avoid disruption of the redd and undue
trampling of the spawning area. Also, in many coastal streams, the water level
during this time is likely to be most suitable for sampling. Prolonged low flow
conditions which often precede emergence will result in maximum deposit of
fine sediment and thus coincide with the critical period mentioned above.
Streams fed by snow melt exhibit somewhat different patterns. The low flow in
such streams is during early fall, about the time spring Chinook begin to
spawn. In these circumstances the late summer flow period would be a more
suitable sampling time.
Even if it were desirable, winter storms and high water levels complicate
sampling of spawning areas. Therefore, it is best to avoid these conditions.
It is possible, however, that certain areas must be monitored because of
anticipated or actual management-related impacts. In these situations, suit-
able sampling times and frequencies must be worked out, on a case-by-case
basis.
5. Methods of Obtaining Gravel Samples
Even though simple photographic methods have been developed for analysis
of surface gravel layers in a stream bottom (Ritter and Helley, 1969), the two
most common methods are frozen core samples originally developed by Walkotton
(1976) and grab (or manual) samples advocated by McNeil and Abnell (1960).
The photographic method is restricted to analysis of surface (or armor)
material visible on a clear water stream bottom. Photographic prints of a
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90
s-
0)
£80
o
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stream bottom segment are analyzed with specialized scanning equipment. These
devices incorporate computation facilities that enable counting, sizing, and
even particle size distribution. Once the system is set up and calibrated,
photographic records of hundreds of particles can be analyzed in a matter of
minutes.
In the frozen core method a metallic tube about one inch in diameter is
driven into the gravel. Liquid carbon dioxide (C02) is throttled into the
tube through a bank of small nozzles. The expansion of the gas rapidly freezes
interstitial water outside the tube, thereby attaching a solid core of gravel
and sediment to the tube, which is then extracted for analysis. The dimen-
sions of the core and the total size of the sample can be varied by a combi-
nation of (a) depth of tube penetration into the gravel, (b) length of time
C02 is applied and (c) use of more than one tube in a given spot.
The manual sampling method consists of inserting a stove pipe or a large
diameter tube (4 to 12 inches) into the gravel bed to a depth of 4 to 12
inches and extracting by hand or scoop the gravel and sand inside the pipe.
An estimate of the suspended material that escapes the gravel sample is ob-
tained by retaining, for subsequent analysis, a subsample of the water column
in the pipe, once the contained water is thoroughly mixed.
There are shortcomings and advantages for all methods discussed. The
photographic method is excellent for extremely large quantities of work but is
restricted to the analysis of the surface layer of the gravel. A suitable
alternative for estimating the particle size distribution of the surface is to
simply pick up one particle every 6 or 12 inches for subsequent sieving.
About one hundred particles should be collected from each site. This method
can be easily combined with benthic sampling if the particles are removed
carefully from the stream and placed in a bucket for subsequent scraping of
attached insects before the gravel is analyzed.
Main advantages of the frozen core method are (a) ability to analyze
samples with depth, (b) ability to sample in deep water and under ice or
frozen streams, and (c) routine application of uniform procedures, i.e., duration
of C02 application and depth of core. Disadvantages are (a) need for elaborate
equipment such as C02 tanks, nozzles, tubes, strong driving rods, hammer,
tripod and pully to extract the sample, and adequate backup equipment in
case of failure in the field, (b) cost of C02 recharge, (c) some prior exper-
ience with the method, and (d) difficulty of sampling in coarse gravel.
Gravel sampling with the frozen core method cannot be combined with
benthic sampling. Many insects attached to rocks are driven away by the
initial pounding of the rod into the gravel and possibly by the application of
the C02. Also, the coarse surface layers that contain most insects are least
likely to freeze because of flowing water. Moreover, frozen cores cannot be
obtained from gravel patches that are not submerged.
Advantages of manual sampling are (a) simplicity of equipment and
procedure, (b) flexibility in modifying sample size, and (c) suitability for
combining with benthic sampling. Disadvantages are (a) loss of suspended
fines, (b) difficulty of sampling in deep water, (c) bias associated with
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different operators who might extract the gravel selectively, and (d) difficulty
of inserting stovepipe into coarse gravel bed.
Usually the disadvantages of frozen core and manual sampling can be
reduced to acceptable levels. For example, Lotspiech (1978) has used steel
tubes instead of copper to reduce problems of bending during extraction. He
also used aluminum C02 tanks to minimize carrying weight while increasing
refrigerant capacity.
Suspended particles in manual samples can be collected in 63 micron mesh
nylon nets using a Hess-type sampler, which also collects the benthic insects.
The sampler is placed in the stream with its two solid sides facing the stream
banks. The upstream side has a sliding screen to allow flow of water in the
chamber yet prevent the drift of suspended matter or insects into the chamber.
The downstream side has a 63 micron net to capture suspended sediment and
insects released from the substrate. Gravel is scraped and washed into the
net before extraction. With this design, gravel samples not only are combined
with benthic samples, but suspended sediments are not lost. To minimize
operator bias "all" substrate components must be removed to a pre-determined
depth, a scoop should be used when possible.
We recommend manual sampling as discussed above for monitoring purposes,
even if not combined with benthic sampling. The overriding advantage is the
flexibility to change the sample size. The larger the sample, the smaller the
sampling bias. Ands to obtain the same degree of accuracy with coarser
gravels, the sample size must be increased. With coarse gravel, it is more
difficult to obtain a large frozen core; thus, these are practical reasons for
manual sampling. The sample size problem is further discussed in the follow-
ing section.
In order to get an idea of the discrepancy that can result purely from
uncontrolled sample size, data are presented in Figure 2 for manual and
freeze core.* These samples were obtained from two coastal streams near Corvallis,
Oregon. The manual samples in Oak Creek were obtained with a wooden frame 30
x 30 x 30 cm inserted in the bed and the freeze core samples were obtained at
a site very close to that for the manual samples. The manual samples from
Berry Creek were obtained from within a metallic pipe 30 cm in diameter in-
serted into the gravel. Before the gravel was extracted the freeze core
sample was obtained from the material inside the pipe. The combined freeze
core and remaining gravel within the pipe gives the manual data. The dis-
crepancy is at times great, varying both above and below the manual sample.
The average sample size with manual method was 24.5 kg, with a range of 8 to
40 kg. The average sample size for the freeze core was 3-5 kg, with a
range of 1.1 to 8 kg. All freeze core samples were obtained with a single
tube.
6. The Size of Gravel Samples
The previous discussion relates primarily to the mechanical advantages
and disadvantages of various sampling methods. Some sampling bias can be
reduced by taking a very large sample. Obviously all attempts to minimize
bias should be made before increasing sample size. Increasing sample size
*The data were obtained from an analysis of unpublished results during the course
of the non-point source study program in Corvallis, Oregon. Data were collected
by Shirazi, Lee* Lotspeich and Reid during the summers of 1977 and 1978.
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60
50
40
30
20 •
10
0 Oak Creek
A Berry Creek
10
20
30
40
50
60
Freeze Core d , mm
Figure 2. Comparison of gravel samples taken with freeze core and manual
sample at Oak Creek and Berry Creek, Oregon
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should not be used to disguise problems inherent in the sampler itself. For
example, with the Hess-type sampler, the main bias results from selective hand
sampling. This bias can be reduced by using a scoop. Another example is the
bias in frozen core sampling when the frozen water is not at least as thick as
the largest particle sizes attached. If only tips of the large particles are
frozen, when the core is pulled out these large attached particles will sep-
arate from the unfrozen surrounding fine particles and bias the sample toward
large particle sizes. If many exposed large particles are lost while extrac-
ting the core, it will be biased toward smaller size particles. In general,
bias can be anticipated on both ends of the particle size range.
The problem of adequate sample size has not been resolved satisfactorily.
Experiments with various gravel compositions are in progress to establish some
guidelines. Preliminary results seen) to indicate that:
(a) the dimensions of the sampler should be several times
(two to four times) greater than the size of largest rocks
found in the sample, and
(b) the percent weight of largest particles in relation to total
sample weight should be small (less than 10%).
For example, core samplers 6 inches in diameter should be adequate if the
gravel is predominately less than 2 inches with 10% by weight larger than 3
inches. When sampling in Chinook spawning areas in Idaho, Corley (1978) used
a 12 inch core. He took 50 to 90 Ib. samples, and percent by weight of rocks
greater than 3 inches ranged from zero to 40%. While this does not give a
definite rationale for sample size selections, it does give an example of the
upper size limits investigators use. Corley's general rule was to pick 5
gallons of gravel per sample, with no special attention given to changing the
sample size for various compositions.
7. Analysis of Gravel—Wet Sieving
Access to spawning areas is not always possible with motorized vehicles.
Therefore, transporting large gravel samples from the stream bank to the
laboratory often presents a problem. Consider a sample size of 50 Ibs.
Carrying as few as 5 samples through rough terrain even one-fourth of a mile
is backbreaking. Serious consideration should be given to on-site analysis of
the gravel. Additional equipment required includes a set of sieves, a bucket
with an overflow nozzle and a graduated cylinder. Only 5 coarse sieves and 2
fine sieves are needed. These are 2-1/2" (64 mm), 1-1/4" (32 mm), 5/8" (16
mm), 5/16" (8 mm) and 5/32" (4 mm) as well as a 63 micron sieve. The content
of the coarse sieves can be analyzed volumetrically using the bucket and
graduated cylinder. The contents of the fine sieves, i.e., size ranges less
than 5/32" (4 mm) and greater than 63 microns should be taken to the labora-
tory for dry weight analysis. Particles below 63 microns are ignored. If
this is unacceptable, a smaller size sieve must be used to replace the 63
micron sieve. Contents of the 2-1/2" (64 mm) sieve can be further discrimi-
nated by passing each rock through individually constructed rigid square wire
frames as a substitute for carrying larger sieves to the field.
8
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Preliminary analysis of wet gravel sieving for sizes below 5/32" (4 mm)
shows that considerable bias can occur because of the water-holding capacity
of finer gravels. Table 1 shows how this error varies as a function of sieve
size for one sediment sample. A 61% error in determination of percent fines
can result for this sample from wet sieving with the 63 micron sieve.
Table 1. ERROR IN PARTICLE SIZE DETERMINATION USING WET SIEVING
Percent (by weight) Water
Sieve Size (mm) in Retained Sample
2
1
.5
.125
,063
10
19
29
49
61
Wet sieving is further complicated by the fact that the error, since it is
also a function of other variables (especially particle size distribution),
will be different from sample to sample. For this reason, dry sieving is
recommended for particles smaller than 5/32" (4 mm). Combining the volumetric
and gravimetric analysis requires knowledge of average gravel density. For
this purpose, the dry contents of the 5/64" (2 mm) sieve should be used for
rock density determination by simply dividing the dry weight of the material
in grams to its displaced volume of water in cubic centimeters.
8. Analysis and Presentation of Results
The most complete analysis of gravel composition consists of a tabulated
listing of gravel size (contents of each sieve) and the weight associated with
that size. This information can be used readily to obtain other useful statis-
tics. The most widely used presentation is a tabulated listing of particle
size and percent by weight of finer (or coarser) particles. From this table
one can find (by interpolation) d84 and d16, that is, the particle diameters
below which, respectively, 84% and 16% of the gravel is finer. The geometric
average (dg) of these two particle sizes has long been used as a first-order
representation of gravel composition. This same number (dg) has been shown to
relate to spawning success. For a more detailed discussion refer to Platts,
Shirazi and Lewis (1978). The geometric mean diameter can be calculated as
follows:
9. Additional data
Implicit in monitoring gravel compositions is the evaluation of a stream
segment used by fish as a spawning habitat. This is only one indication of
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the general condition of a stream system. To broaden the use of this infor-
mation in the context of the total stream system, additional data on the
watershed, on the hydraulics and on the benthic insects may be included.
Important watershed data are soil type, soil composition, vegetation,
drainage area, general slope of the terrain, and silvicultural activities,
including the type and extent of clear-cutting and road building.
Hydraulic information includes water velocity and water depth at each
sampling site, general morphology of the stream bank and bottom, bankfull
water depth, water dredging, general bottom slope and water surface slope, and
when possible the hydraulic conditions during spawning.
When sampling gravel, using the Mess-type sampler, an excellent opportunity
exists to simultaneously collect the benthic insects attached to the rocks and
included within the intersticies.
In general, these data provide the basis for further evaluation of the
impact of watershed management on the stream system. In particular, the
specific use of the data must be decided on a case-by-case basis determined by
the objectives of the study.
10. Estimating Localized and Streamwide Impacts
The ultimate goal of monitoring is to assess the possible impact of
cultural activities on spawning gravel. The parameters used as measures of
this impact can be classified in the categories: (a) changes in the area of
spawning gravel, i.e., the change in the available habitat, and (b) changes in
the composition of the gravel, i.e., the quality of the habitat. For the
latter measures the geometric mean diameter dg is assumed to be a sufficient
1st order of magnitude indicator, for it can be conveniently related to
spawning success. To demonstrate how this information can be used, assume
that the following qualitative judgement applies to gravel composition.
do mm
quality
>1IO good
>9
<7
marginal
<6 poor
Let us also assume that data in Table 2, a hypothetical table, were obtained
from measurements of gravel quality and area on Dream Creek prior to a hypothetical
land slide in 1966. It is shown that throughout the four miles of the creek
the spawning gravel, totaling 510 m2, is of good quality.
Table 3 shows the same information after a land slide. It shows that the
quality of the gravel is reduced throughout, even though the total spawning
area is increased from 510 m2 to 540 nr. The creek has been affected most
drastically in the upstream reaches.
10
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Table 2. SPAWNING GRAVEL AREA AND QUALITY BEFORE LANDSLIDE OF 1966 IN DREAM CREEK
Mile
post
1
2
3
4
Total
Table 3.
Area
m2
100
300
50
60
510
SPAWNING
dg
mm
13
10
12
15
GRAVEL AREA
Good
19
59
10
12
100
AND QUALITY AFTER
% of Total Area
Marginal
0
0
0
0
0
LANDSLIDE OF 1966
Poor
0
0
0
0
0
IN DREAM CREEK
Mile
post
1
2
3
4
Total
Area
ra2
60
300
100
80
540
dg
mm
6
8
9
10
Good
0
0
0
15
15
% of Total Area
Marginal
0
55
19
0
74
Poor
11
0
0
0
11
11
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11. Conclusions and Recommendations
The foregoing rationale for a monitoring program was presented to assess
possible impact of silvicultural activities in a watershed on salmonid spawn-
ing habitat. Two measures, one relating to composition of spawning gravel and
another to the available spawning habitat were proposed. The first measure,
i.e., the geometric mean diameter of the spawning gravel directly affects
survival of fertilized eggs to emergence. It is not difficult to propose
ranges of geometric mean diameter for good, marginal and poor survival. The
second measure, the total area of spawning gravel in a given reach, is keyed
to the quality of this habitat, namely the composition of the spawning gravel.
This information is useful in itself, for it permits comparison of gravel
quality before and after the impact. Conceptually, it is related to effects
on fish survival in larval stages. However, by itself, the information is an
inadequate measure of fish production. It must be supplemented by data on the
carrying capacity of the stream so that one can reach a balance between the
desire to maintain a quality spawning habitat and the optimum number of fish
that the stream can support in a given season. This is a difficult problem to
resolve. Even though there are many on-going attempts to make a rational
analysis of this problem, it will be several years before a satisfactory
answer is found. Meanwhile the use and refinement of the proposed method for
monitoring the spawning gravel should be helpful.
To restate the recommended procedure:
1. Select known spawning areas in stretches of a stream being impacted.
2. Identify patches of spawning gravel and measure the areas.
3. Estimate the range of gravel composition in each patch or, if
possible in the spawning riffle by taking three samples, one each in
coarse, fine and intermediate spots.
4. Use a grab sampler under low water conditions soon after emergence.
5. Collect at least three gallons of gravel, more if the gravel is
coarse.
6. Wet-sieve the gravel on-site and analyze the coarse fraction (i.e.,
coarser than 5/32" (4 mm)) volumetrically.
7. Collect remaining gravel in 63 micron sieve, dry-sieve in the lab-
oratory and analyze gravimetrically.
8. Estimate gravel density, combine analysis and determine geometric
mean diameter.
9. Make a matrix of area—geometric mean diameter of all patches along
the stream reach for comparison after impact.
12
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REFERENCES
Corley, D. R. 1978. Fishery habitat survey of the South Fork Salmon
River - 1977. USOA For. Serv., Internt. Reg., Boise Natl. For.,
Boise, ID. 90 p.
Koski, K. V. 1966. The survival of coho salmon from egg deposition
to emergence in three Oregon coastal streams. M.S. Thesis, Oregon State
Univ., Corvallis, OR. 84 p.
McNeil, W. J., and W. R. Abnell. 1960. Measurement of gravel composition
of salmon stream beds, College of Fisheries, University of Wash., Seattle,
WA, Circular #120.
Platts, W. S. 1974. Geomorphic and aquatic conditions influencing salmonids
and stream classification—with application to ecosystem classification.
USDA For. Serv., Surface Environ, and Mining Proj. R. Billings, MT.
200 p.
Lotspeich, F. B. 1978. Personal communication.
Platts, W. S., M. A. Shirazi and D. H. Lewis. 1978. An evaluation of spawn-
ing sediments used by Chinook salmon. In press, USEPA, Ecological
Research Series. Corvallis Environmental Research Laboratory, Corvallis,
OR.
Ritter, J. R., and E. J. Helley. 1969. Optical method for determining
particle size of coarse sediment. Techniques of Water Resources Investi-
gation, U.S. Geological Survey, Book 5.
Walkotten, W. J. 1976. An improved technique for freeze sampling
streambed sediments, USDA For, Serv. Res. Note PNW-281, Pacific Northwest
For. and Range Exp. Stn., Portland, OR. 11 p.
13
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-6QO/3-79-014
2.
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Monitoring Spawning Gravel 1n Managed Forested
Watersheds-A Proposed Procedure
REPORT DATE
February 1979 issuing date
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Mostafa A. Shirazi, Donald H. Lewis and Wayne K. Se1m
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Ecosystems Modeling & Analysis Branch
Corvallls Environmental Research Laboratory
200 S.W. 35th Street
Corvallis, OR 97330
10. PROGRAM ELEMENT NO.
1BA608
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
CorvalUs Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
200 S.W. 35th Street -- CorvalUs, OR 97330
13. TYPE OF REPORT AND PERIOD COVERED
inhouse
14. SPONSORING AGENCY CODE
EPA/600/02
15. SUPPLEMENTARY NOTES
Contact: M.A. Shirazi, Corvallis, OR (FTS 420-4751)
16. ABSTRACT
SHvicultural activities 1n the Pacific Northwest introduce various levels of
sediments and debris into streams, often degrading spawning habitats of salmonld
fishes. In these mountain streams spawning takes place in riffles where the water
velocity is usually 1.5 to 2.5 ft/sec and water is 6 to 36 inches deep. The substrate
in these riffles are ideal habitats for aquatic insects which in turn respond adversely
to excessive sedimentation. For these reasons, the study of spawning habitats could
provide a relatively simple and sensitive indicator of watershed management Impacts.
Simple but reliable procedures are needed to monitor spawning substrate to assess
the level of these impacts. This paper presents a preliminary rationale for conducting
a monitoring program to assess the impact of watershed management activities on stream
spawning habitats; both on individual spawning sites as well as for the entire stream.
After analyzing results from these investigations it appears that reasonable
balance can be achieved between an acceptable reliability and minimum number of samples
byJ(7^esHi"?t1![!E,the area °f th! 9ravel in the Slte that 1s Potentially usable by fish
and (b) within this area, selecting representative samples to provide a quantitative
[measure of the range of conditions and thus the quality of the gravel
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b. IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
spawning substrate
salmonid spawning
gravelbed stream
monitoring
monitoring
watershed
spawning
18. DISTRIBUTION STATEMENT
release unlimited
19. SECURITY CLASS (This Reportf
Unclassified
21. NO. OF PAGES
20
20. SECURITY CLASS (Thtjpagej
Unclassified
22. PRICE
EPA Form 2220-1 (R«v. 4-77}
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