PROCEEDINGS
OF THE
FIFTH SYMPOSIUM - PACIFIC NORTHWEST
ON
SILTATION - ITS SOURCES AND EFFECTS
ON THE AQUATIC ENVIRONMENT
Department of Health, Education and Welfare
U. S. Public Health Service
Water Supply and Water Pollution Control Program
Portland, Oregon
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FOREWORD
Two years ago the Public .Health Service initiated a project in the
Pacific Northwest for the purpose of testing an idea for a program by
which to better reach and serve
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PROCEEDINGS OF THE
FIFTH SYMPOSIUM - PACIFIC NORTHWEST
ON
SILTATION - ITS SOURCES AND EFFECTS ON
AQUATIC ENVIRONMENT
March 23-24, 1959
Assembled by
Edward F. Eldridge
John N. Wilson
Opening Remarks - E. F. Eldridge
Two years ago I Joined the Public Health Service on a project which
we chose to call "Technical and Research Consultation Project, Pacific
Northwest." One of the major objectives of this project is to stimulate,
encourage, guide,advise, coordinate, and develop research on problems re-
lating to water pollution in this area. This has been somewhat of an ex-
periment on the part of Public Health Service to find better ways to serve
you who are conducting research or technical studies on actual field
problems. Symposiums, of which this is the fifth, have been initiated as
one of the methods by which we hope to stimulate interest in various
problems and to bring groups together for an exchange of information.
These symposiums are informal - they are not conferences in which
papers are read. We have selected leaders who will make brief statements
of the specific items we are to consider. The subject will then be open
for general discussion. Everyone is invited to speak his thoughts.
As you know, the subject of this symposium is "Siltation - Its Sources
and Effects on the Aquatic Environment." We have limited it to the. aquatic
environment, although there are many other phases of the problem which we
might discuss.
Yesterday thirty-three persons took part in a field demonstration of
equipment which took place in the Sandy River near Troutdale about eighteen
miles east of Portland. The following is a list of the equipment demon-
strated.
A. For the measurement of physical and chemical factors in salmon
and steelhead redds.
1. Perueameter for the measurement of permeability.
2. Standpipes for determination of dissolved oxygen, carbon
dioxide, etc., in spawning gravel.
3. Gravel sampler for determination of fines.
D. For the collection of fish-food organisms.
j.. Surber square-foot bottom sauplcr.
2. Reconnaissance ocreen.
3- ri»ianf»t-«»tJve
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Purpose and Scope of the Symposium - John N. Wilson
There has been increasing emphasis in recent years on cooperative
programs in the realm of water resources. Witness the large number of
alphabetized interagency groups: The Arkansas White Red Interagency
Committee, AURBLAC, the Missouri Basin Interagency Committee, MBIAC,
and of course our own Columbia Basin Interagency Committee, CBIAC.
Most of these groups have been assembled with the common goal of wise
development and use of our water resources.
Those in attendance at meetings of such groups are Impressed by
the fact that most of the subjects discussed relate to engineering
aspects of flood control, pool levels, firm power, runoff, snow surveys,
and the like. In the Pacific Northwest, the urgency of problems relating
to the anadromous fish runs has compelled an acceleration of research
applied to fish passage facilities and a multitude of factors in the
preservation of this important resource.
Among these factors is a growing awareness of the need for bringing
water quality control into the whole matter of interagency thinking and
planning for fisheries and for water supplies for our expanding popu-
lation and industry.
Closely tied to water quality control is the significance of aquatic
ecology - the aquatic environment. Streams and lakes are comparable in
many ways with living organisms. We are here dealing, not only with the
cold facts of the amount and distribution of water, but also with com-
plex biotic interactions that take place under the surface of these
waters - interactions that are affected in one way or another by all
accepted legitimate uses of our waters.
Let me explain by citing a striking illustration of where radical
misuse of a water courss has impaired other uses. I refer to the sil-
tation problem in the lower ninety miles of the Bear River, southeastern
Idaho - northern Utah.
Some thirty years ago a fourteen-year-old boy leaped across a grass
covered, bushy gully in the watershed of Five Mile Creek, tributary to
Bear River near Preston, Idaho. Since that day some thirty years ago,
Increased irrigation and agriculture in this erodable sandy soil has
opened the gully and washed an estimated ten million tons of sand of
0.1 - 0.3 millimeter size into the Bear River. Where once a boy leaped
from rim to rim, the distance across the chasm is presently more than
five hundred feet with a depth exceeding one-hundred fifty feet.
The results of this heavy load of settleable material on the Bear
River have been several. The depth of deposition over the entire ninety
nile reach varies from six to eight feet, filling pools and burying rif-
fles which once constituted a favorable environment for one of the finest
trout populations in the intermountain area. Now only a few carp can
survive.
I have persmally had the opportunity _o work with the two states
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on the Interstate pollution problem which has been superimposed upon
that of siltation. The over-all problem has been rendered complex by
the fact that the capacity for natural purification which is normally
available in rivers has been reduced to a very low level. The stream
is a virtual biological desert.
By way of contrast, I'd like to cite the example of a differen':
type of stream in the Middle West where siltation has not been a major
problem. Instead, a heavy load of industrial and municipal waste has
been the problem. Wastes were discharging into a turbulent reach of
this river over a rocky bottom. Because there was little siltation,
there was minimum interference with growth of organisms which are re-
sponsible for natural purification. The resulting rapid rate of as-
similation of these wastes caused the investigating engineers to do a
"double take." Most of them had never witnessed such a remarkable
example of stream self-purlflection.
I cite this because it points up the need for better understanding
of all factors in the aquatic environment. Such an understanding is
essential to interpretations of all aspects of water quality. Investi-
gators armed with knowledge of environmental factors in waters can
inLivpret the reasons for the natural purification cited in the instance
of t:.<3 midwestern stream versus the extremely slow rate in Bear River.
This J.s basic, but often overlooked.
For these reasons, we are devoting the first portion of this sym-
posium to a consideration of the aquatic environment. We shall start
with a discussion of the effecto of siltation and turbidity upon photo-
synthesis in aquatic plants, primary productivity, if you will, followed
by the next principal group in the food chain, the fish food organiens
and culminating in the fish themselves.
The discussions this afternoon will deal primarily with watershed
management and water uses. We will start with the watershed for, as
you all know, water quality control starts with the raindrop falling
on the land. We will then move down along watercourses and include
other water uses which bear on the problem of siltation.
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Turbidity, Sedimentation and Photosynthesis - Dr. Harry K. Phinney
If I took the simple approach to this problca, the usually accepted
approach that generalizations and approximations are sufficiently ac-
curate for biological work, this could be a brief, nost understandable
and enjoyable report. For the sake of contrast, I would like to state
the generalizations that relate turbidity and sedimentation to the photo-
synthetic process and then attenpt to explore the ramifications of
these relationships.
Statement #1. Light passing through a turbid nediun suffers a re-
duction in intensity, in all wave lengths, that is approximately pro-
portional to the concentration of suspensoids. The rate of the photo-
synthetic process is approximately proportional to the amount of avail-
able light. Ergo: As turbidity increases the rate of photosynthesis
decreases.
Statement #2. The physical effect of a layer of sediment is that
of a mechanical barrier to the mass movement of the ambient mediuc. over
the surfaces lying under the sediment layer. Gas exchange between
multicellular organisms or aggregates of unicellular organisns so burled
cannot be accomplished solely by diffusion with sufficient rapidity to
maintain life processes in most aerobic organisns. Ergo: Sedimentation
wil? result in the serious reduction in the phoiosynthetic rate of at-
tached aquatic plant communities. If the reduction is to a level below
the rompensation point, oxygen to carbon dioxido, very marked changes
will occur in the popul< tion.
Sounds scientific, doesn't it? It's scientific enough to warrant
using in educational talks to service clubs. I might even use it in a
lecture to an elementary course in aquatic biology. The thing that
scares me is that 99.97. of the so-called research in U-.3 area of tur-
bidity and sedimentation problems today results in data that allow for
the most part inaccurate conclusions concerning t/nese relationships.
If this continues I can guarantee that similar symposia in 1969, 1>79,
and 1989 will come to the same conclusions as the one today.
The problem to be dealt with is primarily a physical relationship.
However, if biologists do not make use of the means of obtaining exact
information that are available, we are going to continue to talk in
scientific half-truths and generalizations which we cannot use to make
well-founded predictions in special cases where such application of
knowledge would serve a practical purpose. I have been involved in
so much descriptive research where we can tell you what happened and
in a general sort of way why it happened, but have been able to use
this experience only to formulate "educated guesses" when next I'm
called on for an opinion concerning a new problem situation.
"The rate of a simple homogeneous reaction usually is a function
of all the relevant factors, e.g. the concentration of all reactants,
temperature, and in photochemical processes, light intensity. The
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bottleneck stage of photosynthesis may be the supply of light energy,
the supply of reactant (CC>2) or the removal of reaction product."
Turbidity and sedimentation nay affect all of these factors, in some
cases even temperature is affected by turbidity.
First, I shall take up the relationship of turbidity to light and
photosynthesis. The measurement of the effect of light intensity on
thci photosynthetic process was first studied by the Russian botanist
Volkov in 1866. He counted the oxygen bubbles evolved by submerged
aquatic plants placed at different distances from a aun-illuciinate,.3,
frosted glass window. He reported the rate of gas evolution to be pro-
portional to the intensity of illumination. It was later established
that there was a plateau that appeared in curves in which the rate of
photosynthesis was plotted against the intensity of incident light.
This leveling off of the curve has been called the effect of light
saturation and usually occurs at about the intensity of full sunlight
(3-6000 fc of 60,000 lux). Beyond the intensity that brings light
saturation comes a zone of light inhibition.
It was long assumed that these curves exemplified minimal, optimal
and maximal quantities despite the fact that Sachs had already enunci-
ated what was first known as the law of the minimum and nore recently
rather universally accepted as the limiting factor concept. This whole
area of thought was in controversy up to twenty-five years ago, and
even now not all objections have been resolved. Experiments with care-
fulJy treated plant mtr^rials show a simple, direct o^.d reversible re-
sponse of the rate of photosynthesis to at least two oxternal factors:
light intensity and concentration of C02 (and within certain narrow
limits, also to changes in temperature).
The light saturation levels have been determined for a number of
aquatic plants; both algae and flowering plants. Unfortunately, much
of the data cannot be directly compared because of a lack of control of
temperature or C09 concentration. Light v-aluee required to bring the
photosynthetic r?ce to % that of light saturation have been reported
to vary from 0.5 - 20 klux for a variety of species of aquatic plants.
As pointed out by Rabinowitz,the light curves nay present a strongly
distorted picture of the Intrinsic relationship between the rate of
light absorption and the yield of photosynthesis, because a considerable
gradient of light intensity between the light exposed and the shaded
chlorophyll molecules. Even within a single chloroplast the rate of
light absorption may decrease by a factor of five or ten from the light
exposed to the shaded side; or in the case of diffuse illumination,
from the surface to the center of the chloroplast.
In suspensions containing millions of cells the heterogeneous
nature of light absorption is further enhanced by the mutual shading
of the numerous chloroplasts. Consequently, the light curves of
different specimens of one organism, even if they all have the same
content of all the relevant pigments and catalysts and are investi-
gated under the same external conditions, aay nevertheless differ in
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shape, depending on optical density (i.e. the nunber of cells/cm^ in an
algal suspension).
Let us consider, as the simplest example, two suspensions of identi-
cal cells - one optically thin (e.g. transmitting 807. of incident light).
There is no reason (aside fron production of self-inhibiting metabolic
products) why these suspensions should differ in the maximum yield per
chlorophyll molecule in strong light. However, the transition from the
linearly ascending part to the horizontal part of the light curves will
be sharper in the optically thin system (where saturation occurs more or
less simultaneously in all cells), and more gradual in the optically
dense system (where saturation sets in at the surface of the vessel and
spreads inward with increasing intensity of illumination).
Averaging cannot be quite correct because the cells are not actually
exposed to the "average" light intensity, but some are illuminated with
stronger, and some with weaker ..light. This would not matter if the yield
were proportional to intensity; but if the yield declines with increasing
intensity (as it does in the saturation region), the yield that corres-
ponds to a given average intensity will be lower when the spread of actual
intensity is wider, i.e. in the more concentrated suspension.
A second complication arises from stirring, which causes cells to
come successively into light of different intensities. The effect of this
variation is complex. Only if the illumination cycles are much shorter
than the periods required for completion of all dark process of photo-
synthesis can one expect che cells to work, in alternating light and dark,
with the same efficiency.
Just consider the additional complications introduced by the turbid
mediumr (1) reduction in total light intensity, (2) changes from direct
to diffuse illumination, (3) effect of optical density on illumination
of individual cells, etc. If we correct the gas natio (C02/02) for Q£
consumption in cellular respiration we find there is no minimum light
intensity for the photosynthetic process. However, there is a point
(compensation point) at which the photosynthetic activity becomes ap-
parent by release of Q£ that is produced above the respiratory require-
ment of the cell. This then becomes a handy marker for the metabolic
balance. The compensation points have been determined experimentally
for a number of species and the light intensities reported vary from
2-1000 lux. Surprisingly enough some of the plants requiring the highest
intensities were green algae.
Again the experimentally determined data are not comparable because
such things as temperature and C0£ concentration were not held to a
standard. In any case, such data would be useful only as a starting
point for investigations of natural populations under field conditions.
So now we arrive at the question of the utility of the compensation point.
I have little reason to doubt that all here have long since realized that
this datum is the objective of all 24-hour oxygen studies and such things
as black bottle experiments. The objective in such studies is to determine
the level of photosynthetic activity of the autotrophic element of the
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population and whether it exceeds the level of activity of the hetero-
trophic population. However, I find it disturbing that so few studies
have deemed it necessary to attempt to define this relationship specifi-
cally. It seems obviously pointless to determine D.O.D. and Ignore
oxygen production as a dynamic process. There should be no study that
is deemed sufficiently important to require a determination of D.0.0.
and not concurrently study the dynamics of oxygen production under
standard conditions. I will go further and say that one without the
other results in ambiguous data. To relate this physical data to bio-
logical data,laboriously assembled as it must be, is a fraud, for in
the end it cannot be determined whether the physical factors are the
cause or the effect. You may think that yours is a practical problem
and you are not interested in such an academic approach. Out after all
nothing could be more academic, more divorced from reality than D.O.D.
data when all by itself it is interpreted as an index of the metabolic
well-being of the habitat.
Let us see what kind of relationships with light have been es-
tablished for photosynthesis in turbid media. And I quote! » First,
from Dorsey (1940). "The transmission of light by many coastal and in-
land waters is subject to wide fluctuations caused by variations in the
turbidity and in the plankton. The amount of plankton varies with the
season and with weather; and the turbidity with the amount of detritus,
sand, and soil whether brought in by streams or surface drainage or
stirred up from the botton. Measurements of the transmission and of
the effective absorptivi'.y under such conditions are of no general value,
but are of significance with reference to the actual plankton growth at
the place and time considered; many such measurements have been made for
the purpose of obtaining data for correlating plankton growth with the
illumination existing at various depths." Nineteen years ago this was true,
today it is true. The only application we can make of this light trans-
mission data is to corre?ote if. with plankton dev*-* •-•iTunt on a relative
basis; in the same habitct by neans of successive r.aJ&arements. We can-
not relate this data to other situations except by direct comparisons.
All that can be said is "they are the same" or "they arc different."
I don't care whether these two situations are the same or different
(and really neither do you). The only real interest there can be in
establishing such a relationship is to be able to say "for this reason
they ere the same (or different)." Or to be able to predict that a new
situation will parallel or differ from another in response to the tur-
bidity because Because? Because what? Listen to this -
"The three component analysis of the waters of the Wisconsin lakes
indicates that although filtration almost always reduces the color of
the water, the suspensoids remaining in settled waters are relatively
unselective in their optical effect. Moreover, for low colors (Pt
units^ 20), the variations in absorption due to suspensoids is apparently
largely independent of color."
Now this is the profound judgement passed, by one I'm willing to
recognize as a genius of our time; on two hundred and twenty printed
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pages of daca laboriously collected some twenty years earlier by
methods that were already 25 years out of date.
The statement is from Hutchinson's ''A treatise on limnology11 eval-
uating the information from James & Dirge and Whitney done in 1938 by
essentially the same methods as used by Aufsess and Pietenpol ten to
twenty years earlier.
Schuster, in 1903, published a theory of the effect of radiation
on the transmission of heat through matter. Here he set forth very
clearly the philosophy that every volume element within the medium re*
ceives scattered light from every other volume element. This has been
called the principle of self-illumination. In 1905 Schuster expressed
the principle of self-illumination in terns of two diffused fluxes moving
in opposite directions through the material, each contributing back-
scattered flux to the other. It only took 33 years for aquatic biologists
to get around to trying to find out what this meant as far as effects on
illumination in natural waters were concerned. And when they did the
procedure used was that of Schuster, although in 1927, eleven years ear-
lier, Silberstein (Phil. Mag. 4:129) had pointed out that when non-
radiating turbid media ere permiated with light from an external source,
the residue of the unsc&rtered beam obeys a different law from the
scattered.
Dy 1942 S. Q. Duntly of M.I.T. had formulated equations that allowed
him to pronounce the following facts:
"When radiation falls on a layer of particles having completely
random orientation and positions, the total amount of scattering is in-
dependent of the angular cone of incidence, for each element of the cone
will be scattered like a parallel bundle. Accordingly it is true that
the total flux scattered backward and forward is equal to the total of
the portions of the diffused flux scattered backward, that is again
scattered forward and backward, in a system with random orientation and
position of particles. This will not be true in systems where such
orientation exists."
"In the interest of generality it must be recognized that the ab-
sorption coefficient for incident light need not be the same as that for
internal diffused light. Not only is a different path length involved
but in a system not possessing completely random orientation and position
of particles, a greater portion of the light may traverse the layer with-
out striking a particle in the case of incident light, than in the case
of diffused light." And he proceeds to differentiate an equation to des-
cribe the internal optical properties of diffusing material. Unfortu-
nately none of Duntly*s equations contain correction for wave length
differences, all of his work being performed in monochromatic light.
Chandler (1942) in a paper on the biological effects of turbidity
and its variations in western Lake Erie says - "turbidity.. .may influence:
(1) composition, size, duration and time of occurrence of phytoplankton
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pulses; (2) rate of photosynthesis at various depths; (3) position of
the compensation point of higher aquatic plants and phytoplankters;
(4) vertical distribution of rnicrocrustacea, and (5) magnitude of the
commercial catch of saugers,"
Are these statements true? Undeniably they are true. But just
what are the turbidity effects? At what level of turbidity will these
effects arise? What type of suspended matter, eisp. and orientation is
involved? Chandler could not answer these questions froti hia data nor
can I because the turbidity measurements were made by a 30-year old
method based on a theory that does not apply.
In 1954, J. Verduin published a paper on phytoplankton and turbidity
which translated Chandler's data and that of others to an even less
meaningful form and presented it as related to "depths associated with
17. of surface light,"
The reports of Schuster (1903) Silberstein (1927) and Ountly (1942)
have all shown the fallacy of light transmission measurements, whether
estimated in the field by means of a photometer of sane sort or approxi-
mated in the laboratory with a spectrophotoraeter. The calculations in-
volved in these procedures count scattering as another type of absorption.
As far as the photometer is concerned, whether this uses a photoelectric
cell or a direct visual comparison with standards, the methods do not
differentiate absorption from scattering. As Dorsey (1940) says; "The
fraction of the incident radiation transmitted by a given layer of water
depends upon the amount laterally scattered by the water, as well as up-
on the amount truly absorbed, i.e. converted into another energy form.
Dut the distinction has seldom been observed in reporting experimental
data, the entire reduction in intensity being generally described as
absorption. May I point out that the use of the platinum cobalt scale
for anything other than the crudest survey work is a complete waste of
time for the above stated reason even if there was not the other and more
serious objection that visual comparison of different colors is a sheer
impossibility.
I think that it would be wise to also emphasize another vagary of
light in turbid suspensions. As the particles in suspension become more
concentrated, more and more of the light emerging from the turbid layer
is emitted by the turbid particles. In these cases the suspension itself
begins to act as the source of light for the photocell. When a concen-
tration is approximated where the transmitted light is essentially equal
to zero,further changes in concentration of scattering particles means
only a change in the intensity of the light source.
If there is an interest in relating physical and biological facts
concerning populations existing in turbid media, certain critical factors
must be considered.
1. What is the metabolic status of the population (the
ratio). And this does not mean simply D.O.D.s.
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2. What are the light transmitting qualities of the medium.
(a) Absorption
(b) Diffuse scattering
This cannot be simply transmission data nor can it be developed
from photometer readings in the field.
3. What are the characteristics of the susp
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the aquatic environment and where interest is in productivity in the
habitat. These tests do not tell the story as far as light has an
effect on the biota.
Reference was made to a technique for separating the effects of
color and turbidity in water on light transmission which is fairly simple
and shows possibilities. The technique is described in papers by Jull-
ander and Drunse, "Light Absorption Measurements on Turbid Solutions,"
Acta. Chen. Scand. 4, 870 (1950) and _3, 1309 (1949). The method was
discussed as a system to determine the optical properties of turbid
waters.
Much of the literature review on this subject occurs, not in the
water field, but in the book by Rabinowitch "Photosynthesis and Related
Processes," Vol. II, Part II (1956). A very complete bibliography on
the subject is contained in this book.
We cannot measure or understand the relationship between the
metabolic activity of the aquatic biota and the physical factors of the
environment until we are ready to accept the techniques which will allow
for the most accurate measurement of those physical factors* We are
using techniques which are poor and out of date and yet we wonder why
for years and years we accumulate data and the only thing we can do
with it is to make the most general statements with low potential in
application.
There is a practical demand for measurement and such methods are
available in the field of physical chemistry, but are objected to by
biologists as being complex and without the budgetary abilities.
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BIBLIOGRAPHY
Aberg, B. and W. Rodhe. 1942. Uber die mileufacktoren in einlgen suds-
chedischen seen. Symb. bot. upsallens. 5(3): 1-256.
Chandler, D. C. 1942. Limnological studies of western Lake Erie. 11.
Light penetration and its relation to turbidity. Ecol. 23: 41-52.
Dorsey, N. E. 1940. Properties of ordinary water substance. Reinhold, N. Y.
Duntley, S. C. 1942. The optical properties of diffusing materials. Jour.
Optical Soc. Am. 32: 61.
Duntley, S. C. 1943. The mathematics of turbid media. Jour. Optical Soc.
Am. 33: 252.
Duysens. L. N. 1956. The flattening of the absorption spectrum of sus-
pensions, as compared to that of solutions. Diochen. Dlophys.
Acta 19(1): 1-12.
Erikson, II. A. 1933. Lighten tensity at different ^.eptl's in lake water.
Jour. Optical Soc. Am. 23: 170-177.
Hutchinson, G. E. 1957. A treatise on Limnology Vol. 1 Geography, Physics
and Chemistry. John Wiley & Sons Inc., New York. pp. 1-1015.
James, H. R. and E. A. Dirge. 1930. A laboratory study of the absorption of
light by lake waters. Trans. Wise. Acad. Sci. Arts & Lett.,31: 1-154.
Juilander, 1. and K. Drune. 1950. Light absorption measurements on turbid
solutions. Acta Chera. Scand. 4: 070-877.
Pietenpol, W. D. 1910. Selective absorption in the visible spectrum of
Wisconsin waters. Trans. Wise. Acad. Sci. Arts & Lett., 19: 562-593.
Powell, W. M. and G. L. Clarke. 1936. The reflection and absorption of
daylight at the surface of the ocean. Jour. Optical Soc.Am. 26: 111-
120.
Rabinowitch, E. 1. 1951. Photosynthesis and related processes Vol. 11 Part
1 spectroscopy and fluorescence of photoaynthetic pigments;
kinetics of photosynthesis. Interscience Pub. Inc., New York.
Rabinowitch, E. 1« 1956. Photosynthesis and related processes Vol. 11
Part 11. New York. 2080 pp.
Tyler, John E. 1957. Monochromatic measurement of the volume scattering
of natural waters. Jour. Optical Soc. Act. 47(8): 745-747.
Verduin, J. 1954. Phytoplankton and turbidity in western Lake Erie;
Ecoloty 35(4): 550-561.
Whitney, L. V. 1938. Continuous solar radiation measurements in Wisconsin
lakes. Trans. Wise. Acad. Sci. Arts & Lett., 31: 175-200.
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Effects of Siltation on Production of Fish Food Organisms - Don W. Kelley
The subject of the effects of siltation on aquatic organisms is
rather new to me. I ata a regional or district fisheries biologist and
spend almost all of ay time doing so-called fisheries management work
and this discussion is an accumulation of recent nights and week-ends
that I have spent trying to catch up on some of the literature. I an
going to really take you through some of the thinking that I have gone
through hurriedly.
The first thing I would like to say is that in general I believe
that silt in normal quantities in streams ordinarily does not seem to
have a direct effect upon fish. Wallace, in 1951, tested 1$ species of
fish and found no change in the behaviosr of those fish until turbidity
reached 20,000 to 100,000, depending upon the species. He increased
turbidities up to 175,000 and 225,000 ppm before any of these species
died. I think we have all brouQht fish into the laboratory and held
them in the effluent froniigravel plant where turbidities were extremely
high and found that they lived there until they starved to death.
The indirect effects of turbidity and siltation, however, are
often disastrous. I think all of us have seen too that many cases
where the bottoms of streams and rivers are completely covered with
silt and where bottom fauna has disappeared. In many cases the bottom
fauna are killed directly. They too breathe, in certain cases with
gills, and an excess of turbidity or deposition of fine material on
the bottom will smother them, just as it would fish, if fish had to
live in the bottom. We have had a few cases in California over on the
north coast where the silt was ao bad that it smothered the fish. Before
Dr. Fhinney spoke I thought it was pretty obvious that an increase in
turbidity of the stream or lake would affect the photosynthesis. I
think this is still true, although we may not be able to measure it and
that since many of the fish food organisms, be they bottom organisms in
a stream or lake, or planktons, are affected by increased turbidity be-
cause many of them are browsers and need plant life for food. Anything
that affects plant life, particularly microscopic pLant life, is going
to affect fish food organisms.
There have been a great many statements made about the general
change in turbidity, particularly in the Middle West, during the time
when the pioneers broke the sod and increased the turbidity of the middle-'
western streams and caused a tremendous change in the fish population.
The Surber sampler was not available at that time, but we might pre-
sume that at least part of the effect was due to turbidity and siltation
on fish foods.
How important is food? We know that fish need it, but is it the
limiting factor? Arc there other things that £ish need, such as shelter
or spawning area, that or*, presently limiting the sizo of the fish popu-
lation? If food is not the limiting factor, if there is in fact a surplus
of food, perhaps the fish populations are affected in some other way
before the decline in the fish food organisms. I think in some cases
-------
- 14 -
food is not the limiting factor. We have been doing some survey work
on trout streams in connection with natural erosion and erosion that is
caused, or at least accelerated, by mans* activities on the watershed.
I believe, however, that in this case perhaps shelter is the limiting
factor rather than the food supply. Much of the shelter for these small
trout is destroyed.
There has been a general acceptance of the fact that food is a
limiting factor in many cases. K. Redway Allen in a very classical
report, although not concerned with siltation, determines fairly well
that food is a factor that limits the size of the fish population.
It io these situations which occur before you get to the point
where the bottom food is smothered out that bother us. When the bottom
food is smothered out, such as by a mine discharge or a gravel operation,
we can get a clear picture. The problem in this case is purely admini-
strative - problems of law enforcement. But I think we have a much
greater problem before we get to that point. Tt-e thing that we must
try to understand is that there is a vast difference between production
of fish food organisms and a standing crop of fish food organisms. H.
K. Townes, in working on a reservoir in lower Hudson River area, found
that silt reduced the bottom organisms in this reservoir by diluting the
organic debris in the bottom so that animals living on the bottom had a
poor food supply. Allen in his study found also that the standing crop
of food organisms was much less than the production. Richardson, in
1921, in working on the Illinois River, did a vast amount of bottom
sampling. He calculated that the standing crop of fish food organisms
on the bottom will only last the standing crop of fish, a few months
in some cases if the standing crops of organisms were stabilized and
if production ceased. The fish would only last a few months until they
starved to death. He calculated this for a number of different places
in the Illinois River. All these things I believe point out that you
can't measure the effects upon standing crop and have to measure the
dynamic effects upon production.
I would like to know how much sand or silt is permissible in the
bottom of the stream or lake. I want to know how turbid the water can
be and for how long. I want to know too what happens to the silt when
it comes off the hills up in the sierras and does its damage there.
A year or two later it is washed out into the foothills doing its damage
there. Where does it go from there? What happens to the tons and tons
of mining silt that were at one time in California and were washed down
by hydraulic mining? Is it doing some damage now to the ocean or to
the delta? I think these are questions which we must answer. I think
that the engineers can help us and I have just recently realized that
they have been working on silt and siltation for a long time.
I want to know too what sort of research we need on this subject.
Fisheries research in the last two years, at least in this country,
has tended to become more practical than basic. We have, to a great
extent, neglected the habitat.
-------
- 15 -
Discussion - abstracted -
The question was asked, "Are there any experiences which would
indicate that turbidity was advantageous?" An example was cited wherein
the greatest population occurred in waters of medium turbidity. The
production of plankton was inhibited in the more turbid waters by the
depression of light and in clear water by the low concentration of mineral
nutrients. Turbidity carries absorbed minerals which support growth if
not sufficiently high to limit light.
Importnnt to know the type of turbidity or silt. There are cases
where the silt carries high concentrations of lead, copper, and other
toxic substances.
Other than the increase In mineral nutrients, increase in turbidity
is not beneficial. Reference was made to a paper by Ward written about
20 years ago which is controversial, due to the use of trout as an ex-
perimental animal. Since trout are extremely difficult to raise in
aquaria, they destroyed themselves in clear water by their own frantic
activities. In turbid water they were more quiet since they were not
disturbed by outside activities.
It was pointed out that the contribution of the mining industries
to the total silt load is about 0.4 percent. Suggestion made that ef-
forts be placed on correcting the larger contribution and the mining
industry would be cooperative regarding their contribution. It was
pointed out that it was a matter of timing and duration. It seems in-
evitable that the conditions resulting from man's activities will continue
to encroach on the fishery, but the responsibility lies in slowing down
this encroachment.
The question of how much is tolerable or what standards of turbidity
should be used was discussed. It was admitted that the biologist did
not know, but that it would vary widely with conditions. This means that
efforts should be directed toward doing what can be done to reduce silt
loads. Decisions should ba made on the basis of the best knowledge
available and in the meantime basic data should be collected. Activities
on streams which influence the silt load do not necessarily need to be
detrimental. Dams and other impoundments may actually improve fish pro-
duction by settling out the silt if given the proper study.
-------
- 16 -
Effects of Siltation on Success of Fish Spawning - W. P. Wickett
Our general topic is the sources and effects of siltation. The
ultimate aim is to specify undesirable effects and devise means of
alleviating and improving existing conditions. We can recognize some
general relationships between siltation and spawning success and note
a few specific values of survival related to the presence or absence of
fine particles. These help our general understanding but are of little
use for drawing up an action program. Such a program requires particular
values of dependent and independent variables.
First, we should specify what we mean by silt. There are various
standard systems of grain identification. If it has not already been
done, we should adopt some one system. Appendix D16 of "Low Dams" (1938)(
a United States Government Printing Office publication, gives a basis
for discussion. Silt is generally considered to represent particles
in the 0.02 to 0.002 mm range. For the purposes of this discussion all
particles below 2 mm, that is coarse to medium sand, a/:e of concern.
I Intend to deal only with salmonids in thir introduction to the
discussion. Other fish eggs, such as bass, are affected by silt.
California has long been concerned with the effects of silt in salmon
streams. Krogius and Krokhin (1) note that silting hao afi'ected the
Kamchatka Rfver scckeye since 1930, when extensive forest cutting .started.
In a 1954 paper
-------
- 17 -
3. Williams Creek sockeye eggs had a survival race of 7.5% under
silted conditions. In the two years following flushing to
remove silt, the survival was 17.2% and 16.57. (3).
4. Alderdice, Wickett and Brett (4) found a period of maximum
stress occurs between 100 and 200 degree-days of development
when chum salmon eggs were exposed to oxygen levels less than
air saturation. Temporary silting of spawning beds such that
oxygen levels were reduced at this period might be expected to
be detrimental.
5. Wickett (5) gave 50 cm/hr and 8 ppm as minimum standards of
velocity and oxygen content for circulating water in gravel.
In Wickett (6),there are data relating the mean permeability of
fenced streams with the mean survival of pink and chum salmon. Output
can also be described in terms of fry per sq. yd. of stream bottom.
The idea is to present survival in terms of a physical characteristic of
the gravel that can be described without relation to grading curves,
gravel sampling techniques and their associated difficulties. This
appears to be a promising approach.
In Terhune (7), Tables II and IV give a few gravel permeabilities
and their grading curves. Mavis and associates (8) (9) give perme-
abilities for several kinds of sands. Rose (10) developed the laws
governing tho movement of fluids through porous materials. These data
and others like them are useful in considering an action program to
develop permeable gravels that will allow a maximum flow of incubating
water.
One of the most urgent problems is to specify grading curves for
gravels that have the best combination of (a) use by adults; (b) flow
of water to incubating eggs; (c) ease of emergence of fry; (d) stability
under as wide a range of discharge as possible. Another problem is to
develop machines to produce this ideal gravel or gravels in our streams.
REFERENCES
(1) Krogius and Krokhin. Trudy Problcnnikh i Teniatichaskikh Soveshchanii
1956. No. 6, pp. 144-149. Translation Series, F.R.D.C. #92, 1957.
(2) Wickett. J. Fish. Res. Bd. Canada 11 (6):933-953, 1954
(3) Humphreys (unpublished). Summary reports, Biological Station; Nanaimo,
B.C.
(4) Alderdice, Wickett, Drett. J. Fish. Res. Bd. Canada 15 (2):229-249,1950.
(5) Wickett. Trans. 8th Alaska Science Cong. (1957), unpublished.
(6) Wickett. J. Fish. Res. Bd. Canada 15 (5):1003-1126, 1953.
(7) Terhune. J. Fish. Res. Bd. Canada 15 (5):1027-1063, 1958.
(8) Mavis et al. U. Iowa Eng. Scries, Bull. 7, 29 pp. 1936.
(9) Mavis et al. U. Iowa Eng. Series Bull. IS, 31 pp. 1939.
(10) Rose. Proc. Institute Mech. Eng. Gt. Britain 153 (5):141-148, 1945.
-------
- 18 -
Discussion - abstracted -
References were made to the classifications of silt by various or-
ganizations. During the discussion it was indicated that it probably
doesn't matter so far as the study of the aquatic environment is con-
cerned which classification is used. The following classification table
was furnished by the Soil Conservation Service.
Sediment Grade Scales
Size in
Millimeters
4000-2000
2000-1000
1000-500
500-250
250-130
130-64
64-32
32-16
16-0
C-4
4-2
2.00-1.00
1.00-0.50
0.50-0.25
0.25-0.125
0.125-0.062
0.062-0.031
0.031-0.016
0.016-0.003
0.000-0.004
0.004-0.0020
0.0020-0.0010
0.0010-0.0005
0.0005-0.0002
Size in
Microns
Size in
Inches
160-80
80-40
40-20
20-10
10-5
5.25
2.5-1.3
1.3-0.6
0.6-0.3
0.3-0.16
0.16-0.08
2000-1000
1000-500
500-250
250-125
125-62
62-31
31-16
16-8
8-4
4-2
2-1
1-0.5
0.5-0.24
Glass
Very large boulders
Large boulders
Medium boulders
Small boulders
Large cobbles
Small cobbles
Very coarse gravel
Coarse gravel
Medium gravel
Fine gravel
Very fine gravel
Very coarse sand
Coarse sand
Medium sand
Fine sand
Very fine sand
Coarse silt
Medium silt
Fine Silt
Very fine silt
Coarse clay
Medium clay
Fine clay
Very fine clay
How do silt particles in sizes ranging below 2 to 5 mm affect the
survival of salmon eggs and young fry? This question was discussed in
detail by A. C. Cooper as follows:
All of the major sockeye spawning grounds of the Fraser River system
are characterized by a stable flow of clear water over clean gravel with
water turbidities far below the limit that can be measured by the Jackson
Turbidimeter. This superficial observation alone is considered to be
significant evidence of the need for precautionary measures to prevent
the introduction of transportable sediments to these streams from arti-
ficial sources. A major exception to this condition is found in the pink
-------
- 19 -
salmon spawning grounds of the main Eraser River, where large volumes of
fine sediments are transported annually to the sea. Even here, however,
the principal volume of sediment is transported during the spring freshet,
with turbidities during the remainder of the year at relatively much lower
concentration.
This is not to say that the production of pink salmon in this part
of the Fraser River is not affected to some extent by the deposition of
sediments on or within the gravel bed, although too little is known of
the efficiency of reproduction in this particular spawning area to draw
any conclusions at this time* Many of the coastal region tributaries of
the Fraser River nee subject to periodic winter freshets which result in
bed erosion and later deposition of eroded sediments. Production of sock-
eye and pink salmon in these streams is known to be adversely affected by
such occurrences.
Many examples can be given of the detrimental effects on spawning
grounds of abnormal quantitieo of suspended sediment in rivers, due to
natural and artificial causes. An outstanding example has occurred in
the Wechako River, one of the principal tributaries of c.he Fraser River,
which has been dammed and diverted for the production of power. The spill-
way for the reservoir discharges large volumes of wate,? down a former
minor tributary of the Nechako. TheHe spills have resulted in large scale
erosion of the tributary valley and the eroded materials have been de-
posited in the Nechako River on what used to be n major spring salmon
spawning area. As a reoult of this, there is little doubt that an area
which formerly supported a population of 5000 to 7500 spawners, has
been removed from productions for many years.
Another example of a different type of effect of transported sediment
has occurred at Seton Lake. Here, glacial water from Bridge River has
been diverted through a power generation plant into Seton Lake. This
lake was once quite clear, and Insofar as can be determined, nearly identi-
cal to neighboring Anderson Lake, which lies upsf.ream and is not affected
by the diversion. Seton Lake is now quite turbid, and present studies
are revealing marked differences in the production of plankton; Anderson
Lake producing on the average about five times as much as Seton Lake.
These differences in production of plankton have not yet been related
to differences in production of sockeye but it is reasonable to expect
that this will be so.
In connection with an immanent problem of disposal of silt bearing
wastes from gold placer mining operations, the Salmon Commission has
made a study of the effects of transported and deposited sediments on the
flow of water through salmon redds. Other concurrent studies of the
characteristics of spawning redds have supplied complimentary information
necessary to understanding the manner in which silt can affect the sur-
vival of eggs in the redds.
It is known that an adequate flow of fresh well oxygenated water
through the gravel redd is essential to good-survival of the salmon eggs,
and that survival is directly related to the rate of flow. This is
-------
- 20 -
demonstrated by data obtained by Pyper in 1954 (Figure 1). The mortali-
ties which occurred are believed to be directly attributable to oxygen
deficiency in certain portions of the redd. No detailed internal exami-
nation of redds has been made to determine local oxygen deficiencies,
but the reduction of dissolved oxygen at various flows is easily demon-
strated. The necessary flow to obtain good survival of eggs will there-
fore depend on the physical character of the material in which the redd
is' located and in the number and placement of the eggs and alevin within
the nest.
Sediments in rivers can be shown to be detrimental to the survival
of salmon eggs in redds through lack of oxygen, either by suffocation
due to coating of the eggs or by suffocation due to reduction in supply
of oxygen bearing water. In extreme situations, the lack of removal
of noxious waste products may also contribute to mortality, although
we have not attempted to investigate this to date. Wherever in our ex-
perimental vjork, flows of water have been reduced sufficiently to cause
nearly complete removal of oxygen from the water by the gravel and eggs,
accumulations of decomposing organic materials coat th<->. surface of the
water leaving the experimental chamber. The effect of depositions of
sediments on the surface of a gravel stream bed is to reduce the flow
of water into the bed. This can be demonstrated with £ permeater as
shown on Pi pure 2. The results shown on the Fi^'TG are not to be con-
sidered as generally applicable to all situation': and gravels, but i.hey
do demonstrate the magnitude of flow reduction which occurs for even
minor additions of sedime.it. The finer sediments, less than 0.3 mn size,
were found to be more effective in reducing flow than coarse materials,
as would be expected.
Experiments with this same type of equipment, with sockeye eggs in
the gravel have shown that survival of the eggs generally follows the
same relationship to flow found by Pyper, although the relationship was
not so well defined. Length of exposure to the reduced flow conditions
may have bearing on the mortalities incurred, although this was not
clearly indicated by this experiment. It is believed that the length
of time required to kill eggs at critical levels of D.O. concentration
is relatively short, and that the mortalities observed from various
lengths of exposure to silt deposition merely reflect a range of mini-
mum flows obtained through the gravel as a result of the silt depositions.
While it may not be possible to predict with great accuracy the exact
effect of a given amount of deposition of sediment on a stream bed on
the survival of eggs in the gravel, the mechanism by which such deposits
affect the eggs is simple to understand, if not to measure, and it can
be predicted with certainty that survival of the eggs will be lowered.
So far we have been considering only those sediments which are
actually deposited in the stream bed. However, examinetion of the
sources of flew of water through stream beds has caused us to examine
the possible effects of suspended materials which are too fine to be
deposited in the stream bed. During a study of the mechanics of flow
through stream beds It was found that the pattern of flow of water
-------
- 21 -
through the bed depends on the nature of the gravel surface. If the
bed is smooth and on an even gradient, flow lines through the gravel
will generally be parallel to the bed, with some interchange between
Vrs. stream and the bed near the surface. If a few large rocks are
placed on top of this bed, the flow remains parallel to the surface
below about one foot of depth, but interchange at the surface is greatly
increased. From these studies it is evident that eggs situated below the
hump of 'a redd are in an excellent position to receive a fresh supply of
surface water. It was equally evident, however, that if the water veloci-
ties within the gravel, even though they were not deposited on the surface,
then it might be expected that such deposition would reduce the flow of
water through the gravel and result in coating of eggs with deposits, there-
by reducing survival of the eggs.
It can be rationalized that the rate of removal of silt from the
water flowing over the gravel will be a function of gravel permeability,
the concentration of suspended materials, the velocity of surface flow
over the bed, and the topography of the bed. In orcU.r to test this re-
lationship a series of experiments have been made, in which a closed cir-
cuit of turbid water containing a known constant concentration of sediment
finer than 74 microns size was circulated over a gravel bed with surface
configurations similar to those shown in the slides. Surface water
velocities were varied within the range of the pumps,,-up to 2 fps and
were kept high enough to prevent deposition of the sediment.on the gravel
surface. During the course of the tests it was found to be necessary to
continually add sediment to the water to maintain the constant turbidity
and that the rate of addition of sediment decreased with time. It was
also found that the permeability of the gravel bed decreased with time,
compared to a control bed of gravel submerged in clean water. This is
illustrated by the following data.
Permeability mot/hr
Time Rate of Addition of Silt Corrected for
Minutes Gms/min/sq. ft. change in control
0
580
2995
5085
9130
.362
.217
.109
.0955
.0498
1,055,000
1,092,000
614,000
437,000
229,000
It was also found that there was a relationship between the variables
examined of the for R s E3VnZ where
R • rate of accumulation of silt in gms/min/sq.m
K S permeability in cm/min
V m surface velocity in cm/min
1000
Z - a factor depending on surface topography.
It is also known that permeability is a function of the square of a
representative particle size, porosity and water viscosity, and also that
-------
- 22 -
the representative particle size and poroBity vary linearly with the
amount o.f fine sediment accumulated in the gravel. Us'rig these re-
lationships it i<4 possible to determine the change in f.crrneability
of a gravel of known grading and porosity, which is found to be a
function of the product of time and suspended sediment concentration.
Thus, for one type of gravel examined, the permeability of the gravel
would be reduced 95.7% in 240 days with a suspended sediment concen-
tration of 25 ppm. This same reduction in permeability could have
occurred in 24 days with a concentration of 250 ppm. The results of
these tests must still be considered very preliminary o'id analysis of
the data on hand is still incomplete, but there is evidence that even
small amounts of suspended materials in streams can have a very signifi*
cant effect on the flow of water through salmon redds and thus on the
survival of eggs. The situation actually is not as simple as I have
indicated here, since permeability also varies with water temperature,
and since in many cases the shape of the gravel surface changes during
the egg incubation period, thereby reducing the rate at which any sedi-
ments present would be accumulated in the gravel. However, the results
obtained to date emphasize the need for clear water if optimum possible
survival of eggs is to be obtained.
-------
- 23 -
Sediment Concentration in Streams of the Pacific Northwest - Elliott M.
Flaxraan
Mr. Flaxman distributed a table (see r.able following this dis-
cussion) showing the results of measurements of concentrations of
sediment in streams of the Northwest and a map showing the location
of the stations where the measurements were made. The map was general-
ized and not in such detail as to allow a prediction in any one area
that a certain silt load will be produced. It gives a general picture
of the contribution of various areas in the Columbia Basin to the sedi-
ment load. The table is the result of the combined efforts of a number
of State and Federal agencies.
There are several conditions in the Columbia Basin that give rise
to high concentrations of silt. Heavier concentrations were during the
winter in Western Washington and Oregon where rains are of long duration
producing higher flows. There are a few streams in Western Washington
that contain glacial rock flows produced in the summer time.
In the eastern portion of the area high concentrations were ob-
tained by the melt of snow cover combined with heavy rains In the spring.
Most of the values on the maps are suspended sediment loads. The only
total sediment loads are those shown for Southern Idaho where high con-
centrations result from denuded range lands and placer mining operations.
Most of the suspended sediment load will be in the silt sizes.
It was suggested that if the biologist could decide as to the re-
lationship between sediment loads and the aquatic problems, the Soil
Conservation Service would be glad to exchange data.
Discussion - abstracted -
The questions regarding samplers and techniques were discussed.
The Interagency group studying the problem has developed and standard-
ized samplers. The samples were integrated by lowering the sampler
to the bottom and raising it upward through the section. Residue was
dried and weighed. The results were reported in the percentage of the
dry weight to the total weight of the water mixture.
Total loads were determined by construction of sills across the
stream. The turbid flow caused by these sills threw all of the sedi-
ment Into suspension. The sampler was held just below the lip of the
sill.
Several drawings of samplers were shown and discussed. BMH53
sampler developed by the Corps of Engineers for bottom sampling -
a hand sampler. The USDM54 is an automatic type sampler also from
the Corps of Engineers.
The Corps, Bureau of Reclamation and Soil Conservation Service
use a unified soil classification system. The Service is writing a
-------
- 24 -
handbook in which they are recommending the use of the sediment grade
scale previously tabulated in these proceedings. These were developed
by a Task Force of the American Geophysical Union which was set up
for the purpose of standardizing technical classifications.
The following reports published by the Corps of Engineers pertain
to the measurement and analysis of suspended sediment. (Supplied by
the Geological Survey).
No. 1 - Field Practice and Equipment used in Sampling Suspended Sediment.
No. 2 - Equipment Used for Sampling Bed-Load and Bed Material.
No. 3 - Analyelcad Study of Methods of Sampling Suspended Sediment.
No. 4 - Methods of Analyzing Sediment Samples
No. 5 - Laboratory Investigation of Suspended Sediment Samplers.
No. 6 - The Design of Improved Types of Suspended Sediment Samplers.
No. 7 - Size Analysis of Suspended Sediment Samples.
No. 8 - Measurement of the Sediment Discharge of Streams.
No. 9 - Density of Sediments Deposited in Reservoirs.
No.10 - Accuracy of Sediment Size Analyses by Bottom Withdrawal
Tube Method.
No.11 - The Development and Calibration of the Visual-Accumulation
Tuba.
No.12 - Some Fundamentals of Particle Size Analysis.
-------
-25-
Sedlment Concentrations In Streams In Che Pacific Northwest
Stream No. of Maximum Minimum
~" Samples Cor.cen. Cone en.
PJP.M. P.P.M.
Western Oregon
Tualatin R. 320 390 10
Molalla P.. 313 560 T
Pudding R. 330 315 T
S. Yamhill R. 342 800 12
WillameLte R. (Salem) 327 400 10
Luciamute R. 342 410 T
SJnf.iam R. 327 503 T
N. Santiam R. 252 250 T
S. Santiam R. 321 370 T
Calapooya R. 323 340 10
Marys R. 339 500 T
Long Tom R. below Fern Ridge Dam 328 279 10
Long Tom R. at Elmira 324 12$ 7
Coyote Cr. 330 156 16
McKenzie R. 331 240 T
Willamette R. (Springfield) 318 350 T
Coasi. Fork Willamette R. nr. London 328 400 T
Coasu Fork Willamette R. below Cottage
Grove Dam 318 260 T
Row R. nr. Star 331 330 T
Row R. below Dorena Dam 108 130 T
Middle Fork Willamette R.. 312 380 T
Columbia R. - Vancouver 394 420 T
Columbia R. - Bonneville 58 638 10
Columbia R. - 1948 flood Bonnevilie 14 1073 57
Illinois R. 15 204 T
S Fk. Coquflle R. 15 38,200 2
Ashland Creek 15 2,410 2
Wilson R. 15 295 9
S. Umpqua (Brockway) 15 5,850 T
Calapooya 15 2,930 T
S. Umpqua (Tiller) 15 853 T
N. Umpqua (Glide) 15 2,100 3
Elk Creek (Tiller) 15 450 T
Little R. 315 777 2
Wilson R. (Lee1a Bridge) 15 229 4
Flynn Creek nr. Salsdo 180 83 0
Deer Creek nr. Salado 180 148 0
Needles Branch nr. Salado 180 92 0
Western Washington
Green R. 132 1,900 0
Chehalis R. 15 IM 3
Skookumchuck (Bvcoda) 15 98 2
Cowlltz 15 112 27
-------
!_/ Maximum daily -26-
2/ Includes measurement of bedload
as well as suspended load.
(continuation - IJestern Washington)
{Stream
E. Fork Leviis R.
Skool-.uuchuck (Tenino)
S. Fork Newaukum (Forest)
S. Fork Newaukum (Alpha)
M. Fork Newaukum (Water Intake)
N Newaukura (Forest)
tJhite R below Emmons Glacier nr.
0 No. of
Samples
15
15
15
15
15
15
Enumclaw 9
Maxiuum
Ccncen .
P. P.M.
102
88
195
71
65
304
15,500
Minimum
Cone en.
P. P.M.
4
1
13
T
T
T
520
Dully Creek nr. Vale
Crooked R. nr. Prineville
Umatilla R. nr. Hermiston
Umatilla R. at. Pendleion
Columbia R. at Pasco
Snake R. at Central Ferry
Kslla Ualla A. nr. Touchet
loucheL R. nr Touchet
Yskitna R. nr. Richland
5. Fork Palouoe R.
]'''ov.r Mile Creek
I-licsouri Flat Creek
Eastern Oregon
200
87
18
ga s tern Ha shington
1,780
1,180
4,540
C.500
36
31
2,000
2,000
2,000
Southern Idaho
680
935
46,000
82,000
808
9,00017
13,6001/
5.00C-T/
11
7
10
T
T
23
T
T
6
T
T
T
Boise 1. nr. Twin Springs
Boise R. QL Notus
Boise R. at Dowlin^ Ranch 2_/
Cnttonwood Creek nr. Arrov;rock res.2_/
Grouse Creek -'
Moore Cr. above Granite Creek nr.
Idaho City
Moore Creek above Thorn Creek
Granite Creek nr. Idaho City 2/
r.cnnock Creek nr. Idaho City2/
Pine Creek nr. Idaho City _2/
Pine Creek above Barry Placer D
Elk Creek nr. Idaho City J?/
Elk Creek above Gold Hill placer
diversion "if
Cottonwood Gulch 2_l
New York Canal 2/~~
ver
2/
525
ii
•i
:l
H
ii
t
ii
i
525
i
H
590
l.clO
235
18,700
93, COO
2,900
4,390
:i,200
10,900
4,220
85,000
56,300
Kootenai R. at Leonia Bridge
Kootenai R. at Newgate
Clark Fork at Plains
l.S'iO
42,000
1 3,720
Nor uhern Idaho
141 810
British Columbia
885
182
Montana
175
237
T
T
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Watershed Management - Grazing, Deforestation and Road Building -
William Builard
This discussion deals largely with the sources of siltation
and what can be done about it. Grazing, deforestation and road building
do not need to have the deleterious effects it so often has. With care-
fully managed operations we can avoid most of the soil disturbance which
causes the trouble.
Mr. Builard presented the following outline of lactors to consider
in watershed management to the end of controlling erosion and sub-
sequent siltation of streams.
I. Causes and Sources of Siltation
A. Natural
1. Glacial "flour"
2. Avalanches and landslides
3. Soil creep and slump, rock weathering and talus
4. Channel degradation
5. Channel aggradation and barkcutting
6. Fire and subsequent erosion
7. Grinding of stream debris loads during high flows
8. Reduction of cover density and soil disturbance by
big game concentrations
9. Natural debris jams in channels
B. Man-caused
1. Soil-disturbing operations on watersheds
a. Timber harvest
b. Road and other construction
c. Right-of-way clearing
d. Grazing by domestic stock
e. Cultivation of soil for crops
f. Recreation concentration
g. Mining
h. Fire and subsequent erosion
2. Channel-disturbing operations
a. Timber harvest
b. Road construction
c. Grazing domestic stock
d. Mining
e. Dam and diversion construction
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3. Runoff - concentrating operation
a. Some timber harvest methods
b. Road and trail construction and drainage
c. Urbanization - Impervious roofs and pavement
II* Correction of Causes of Siltation
A. Manage Operations to Avoid Hazards
1. Timber harvest
a. Layout of cutting areas
b. Direction of log removal-yarding methods
c. Restrictions on equipment - type and use
2. Grazing (in terms of cover density and soil conditions)
a. Big game management
b. Control of grazing by domestic stock
3. Mining
a. Control of tailings
b. Control of dredging
4. Agriculture (conservation farming, improved cultural
methods)
a. Contour strip cultivation
b. Grassed drainage ways
c. Cover crops
d. Efficient irrigation
5. Road construction
a. Location and design
b. Construction methods
c. Drainage disposal
d. Slope stabilization
e. Surfacing
III. Rehabilitation of Sources of Siltation
A. On Watershed Slopes
1. Improvement of cover density and soil stabilization
a. Tree-planting and grass-seeding
b. Control of grazing
c. Control of fire
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2. Control of runoff and erosion
a. Terracing
b. Contour furrowing and trenching
c. Gully plugs
d. Drainage diversion and sediment settling
e. Conservation farming
B. In Channels
1. Bank protection works
2. Clearing jams of floatable debris
3. Fills to stabilize channel bottoms
4. Debris basins
IV. Current Programs to Control Siltation
A. Federal and State Agency Programs
1. Education and information
a. Hazards of land abuse
b. Prescriptions for proper methods of land use
2. Control of operations by land-managing agencies
3. Stipulations
a. Operating contracts
b. Easements and rights-of-way
c. Licenses and permits
3. Rehabilitation projects
4. Soil bank and conservation reserve
B. Cooperative Programs
1. Self-regulation by private agencies
2. Education and information
a. Society of American Foresters
b. Northwest Pollution Control Council
c. Northwest Forest Soils Council
d. Soil conservation districts
e. Sportsmen and conservation associations
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C. Legislation (primarily State and County)
1. Public Health Codes
2. Forestry Codes
3t Fish and Game Codes
4. Dredge-mining Codes
Overgrazing is one of the factors in causing siltatlon. Cover is
removed and the soil compacted. Rain and snow-melt cannot penetrate
the soil and runoff is increased causing erosion. Usually the best
soil is removed and ends up in river bottom lands or in stream beds.
This soil should be kept in the uplands and forests.
There are several methods of control of erosion including: refusal
to graze or log on wet and soggy soils; use care in the layout of cutting
areas and access roads; do not work close to channels or live streams;
select type of equipment; train the operators; and rehabilitate the dis-
turbed areas.
Road construction is one of the most significant operations as
regards siltation. There is too long a lapse between construction and
stabilization. The disposal of cut material should not be made in the
vicinity of a stream. This material can be the source of siltation
for many years.
Discussion - abstracted -
Does the Forest Service vary regulations with area? Yes, the
management varies with soil types terrain and other factors.
Who makes the regulations? The Service has general policies, but
the ranger who lays out the timber sale will develop the regulations
to fit the area.
Are regulations adequate to control siltation? Not always. There
is still the need for research, although experience has shown certain
practices to be adequate.
Due to heavy erosion in the past, certain areas have reached a
point of stabilization in which even rapid runoff does not cause ex-
cessive erosion.
Is it practical to leave a strip of trees along a stream as a pro-
tection against siltation and to provide shade for aquatic life? The
answer will depend on local conditions as will the depth of the strip.
It is practical, but the policy should be flexible.
If we are to have the best multiple use plan for land and wate?
we must use a united approach in which all agencies participate. Forest
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rangers and road builders are not always aware of the problems and
effects. The biologists should work with them.
(Mention was made of a meeting of the Washington Association of
Fish and Game Commissioners to be held in Portland the last week in
June. The purpose of this meeting is to develop a uniform code for
fishery habitat control. Eleven western states are working on this
code. It will involve forest: management, highway cone£8rwetiong and
all other operations influencing land erosion).
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Mining and Dredging Wastes - Forest Hauck
This subject of the effect of mining and dredging wastes on the
aquatic habitat is a controversial subject. However, there are ways
of coming to a coraaon point of agreement between opposite points of
view.. The State of Idaho has some of the largest wilderness areas In
the nation. The silt loads to streams in these areas are small for
the most part except where industry has moved in and eaused damage.
Four years ago, the Federated sports clubs introduced en initiative
which resulted in the adoption of a dredge mining waste law, This
carried by a large majority.
We have four general sources of mining wastes, namely:
1. The pulverized rock which result from grinding in various
types o£ mills and which vary in size from large rocks to
substances which will pass a 1000 mesh screen. They arc
usually carried away from the mill in wa^er together with
other substances used to separate tho mineral from the rock.
Since nost of the mines are located in mountainous country,
the natural place to deposit them is in the stream bad.
2. The waste ores themselves which escape the milling process
or which have no value. Those make their way to the stream.
3. Mine waters which may be pumped or which run from the mine
to the stream. Theso carry chemicals from the lodes.
4. The chemicals which are added in the milling process to
separate the minerals from the rock.
Aa methods are improved for milling, the siltation problems in-
crease. Mill tailings are becoming finer and are carried much further
downstream than formerly. Lower grade ores are being handled and con-
sequently greater quantities of rock are processed adding to the silt-
ation problem.
Now chemicals and disintegrating agents add to the hazard down-
stream. Frothing agents produce toxic conditions in the stream.
The substances deposited in the streams are so fine they feel
like slimy material. The high turbidity cuts down the light and inter-
feres with photosynthesis. Silt loads are carried farther downstream
each year by freshets which pick up the deposited material and move
it down to a new locotion.
Many of the salts of the. heavy metals are toxic. For example,
lead and zinc sulfide. Some other salts undergo chemical changes and
become soluble in which form they may be toxic.
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Just after World War I a litigation occurred between agricultural
and aining interests in the Coeur d'Alene. The mines on the south
fork were sued. They alleged that the chemicals were poisoning the
soil and cattle and horses were killed. The mining companies then
acquired oost of the faro lands and used then for the dispersal of
the wastes to keep the material out of the streams.
More recently the Game Commission has had losses of wild life,
especially duck and swan in the sane area. Evidence indicate lead as
the cause.
In some cases chenicals used combine to form toxic substances.
An example is t:se cobalt mines on the headwaters of the Salmon River.
Here ferric salr.a and sulphuric acid combine with the effluent from
ponds used to s?ttle tailins8 causing a precipitation of iron oxide
on the stream bee? for a distance of 45 to 50 in.Mes. The problem was
solved by adding lime to the waste and settling the iron in a pond.
Predge mining is nothing but a large placer operation. Equipment
is usually located on a floating barge. The raptorial is taken from the
stream and returns the unwanted solids to the stream bed. As a result
of the new dredging legislation in Idaho, the operator is required to
smooth the stream bed, replant the area and put the stream back in as
near its natural condition as possible. Water used must be returned to
the stream in a reasonably clear condition.
Dredge mining removes the fines from the soil making it more
porous. This results in erosion during the spring runoff. The amount
of silt from a dredging is very high and continues for years after the
operation has ceased. Not only does it affect fish life, but it inter-
feres with other water uses such as irrigation and fills reservoirs
and canals.
Eggs and fry are found in certain Idaho streams every month of
the year. Winter operation of dredges are, therefore, just as damaging
as those at other periods.
Experiments conducted with dredge mining wastes showed that in
every case the mortality of eggs, fry and fingerlings was greater in
silt ladened water than in clear water. The silt used in these tests
was taken from a pond in which tailings were settled and the concen-
trations used were the sane as occurred in the stream one mile below
the dredge under study.
Reference was made to a study by Dr. Ellis on Coeur d'Alene Lake.
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Sand and Gravel Operations - Richard Wagner
There are several methods by which gravel is removed from a
stream bed. These consist of a drag line and bucket which moves up
and down the stream over the gravel area, the claa shovel which is
more stationary, and the scoop-mobile which is noved in during low
water to remove a bar of gravel.
The Washington Pollution Control Connission require the ponding
of gravel washings before discharge. Tests are made above and below
an operation using the Jackson turbidineter but since this measurement
depends on lighi transmission, the results did not establish the problem.
Variations in the size, shape and type of particle exhibit different
effects and the results are not quantitative. Quantitative measure-
ments by actually weighing the material do not tell the story. So
we decided to measure the deposition on the bottom and the effect on
fish food organisms, primary insects, clans, snails, etc. This proved
to be a more effective measure for persuading operators of pits that
their operations were damaging the stream.
It is one natter to control an established operation and another
to control fly-by-night gravel removal. The latter are commonly associ-
ated with highway construction. The removal and washing of the gravel
for the highway operates during the construction of a certain stretch
of road and then moves on when the contract is finished.
A source of siltation in connection with gravel removal is the dis-
posal of the top soil. This may be pushed into a stream bed or piled
next to the pit. The material is soft and subject to excessive erosion
even with minor runoff.
Silt settles in pockets and pools in the stream bed. In the smaller
tributaries these are resting areas for smaller fish.
Tests were made to determine the effect of the organic constituents
in the silt load. It was found that the oxygen demand was great. Oxy-
gen concentrations decreased to low levels in a few cases.
A study of bottom deposits showed that the material below the
surface in some cases was anaerobic and the substances leaching from
the deposits were extremely toxic. These properties may be due to
the reduction of such compounds as arsenates which may increase the
toxicity.
In October, 1957, the Washington Pollution Control Commission
made an investigation of turbidity and siltation of the Wynooche River
in Western Washington. The source of the turbidity and silt was a
gravel removal industry - drag line operation. Objectives of the study •
were:
a. To determine: (1) the normal suspended solids and turbidity
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of the river water, (2) the suspended solids and turbidity of the
river water when influenced by the gravel operation.
b. To determine by bio-indices, the effects of the introduced
sedimentation on the aquatic insect population.
c. To determine the effects of the induced siltation upon the
habitat utilized by juvenile salmonoid fishes.
This is a permanent gravel operation with fixed equipment.
Part of tho draglining takes place in the river channel but over a
number of years thera has been enough draglining to produce a sort
of core off to one side of tha main channel. A dyka his bo.en con-
structed at the lower end of the core to help to keep the turbid water
from being transported direct to the river.
Analyses of the water were made for suspended solids, dissolved
oxygen, and turbidity and hydrogen ion concentration. Samples for
aquatic insects were collected by means of a square foot bottom sampler.
Very briefly, the results are as follows:
Normal turbidity upstream indicated that the water was clear and
the bottom free from silt. Immediately downstream the turbidity ranged
from 91 ppm and 102 ppm of suspended solids. The introduced sedimen-
tation caused a marked reduction in the aquatic insect population.
Quantitative analyses of bottom samples showed population reduction
75 to 85 percent below the gravel operation. The reduced insect popu-
lation in the silt deposited in the gravel has created a condition
which has eliminated two basic needs (food and cover) for young trout
and salmon. This, in turn, will reduce survival rates of these fishes.
Although the silt deposits in this area below the operation and the
turbidity values were lower than some accepted standards elsewhere in
the country,they still appear to be too high for reasons given above.
Tests showed, however, that where draging was restricted to the cove
area behind tho dyke, turbidity and silt were not GO hnmful as where
the draglining was taking place in the main channel.
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ATTENDANCE AT FIFTH SYMPOSIUM
BAKKALA, Richard, U. S, Fish e.nd Wildlife Service, Seattle, Washington
BARNABY, J. T., U. S. Fish and Wildlife Service, Portland, Oregon
BENSON, D. J., Oregon State Sanitary Authority, Portland, Oregon
BULLARD, W. E., U. S. Forest Service, Portland, Oregon
BURT, W. V., Oregon State College, Corvallis, Oregon
CAMPBELL, Homer, Oregon State College, Corvallis, Oregon
CARTER, Glen D., Oregon State Sanitary Authority, Portland, Oregon
COBLE, Dan, Oregon State College, Corvallis, Oregon
COOPER, A. C., International pacific Salnon Fisheries Comm., New Westainstov
CHAPMAN, D, W., Oregon State College, Corvallis, Oregon B.C.,
CLOTHIER, Win. D. , Oregon Fish Commission, Newport, Oregon
CHADWICK, H. K., Calif. Department of Fish and Game, Sacramento, Calif.
CULVER, R. I., Oregon State Sanitary Authority, Portland, Oregon
DAVIS, J. J., General Electric Company, Richland, Wa;>!ii-.igton
DUNSTAN, G. H., Washington State College, Pullman, Washington
DWORSKY, L. B., Public Health Service, Portland, Oregon
ECHO, Mike, Washington Department of Fish, Aberdeen, Washington
ELDRIDGE, E. F., Public Health Service, Portland, Oregon
FLAXMAN, Elliott M., Soil Conservation Service, Portland, Oregon
GBCOM, Jack I., U. S. Forest Service, Portland, Oregon
GANGMARK, H. A., Bureau of Commercial Fisheries, Seattle, Washington
GUNSOLUS, R. T., Oregon Fish Connission, Portland, Oregon
HANSON, W, 0., U. S. Forest Service, Portland, Oregon
HART, Don, U. S. Forest Service, Portland, Oregon
HAUCK, Forrest R., Idaho Department of Fish and Game, Boise, Idaho
HERMANN, R. B., Oregon Fish Commission, Portland, Oregon
KATZ, Max, Oregon State College, Corvallis, Oregon
KELLEY, D. W., Calif. Department of Fish and Game, Sacramento, Calif.
KIRKNESS, Walter, Alaska Dept. of Fish and Game, Juneau, Alaska
LINSTEDT, Kermit, U. S. Forest Service, Portland, Oregon
LIVINGSTON, Al, Washington Pollution Control Commission, Olyoapia, Wash.
LINDSAY, C. E., Washington Dept. of Fisheries, Quilcene, Wash.
LEGILBERG, Herb, Washington Dept. of Fisheries, Quilcene, Wash.
MASON, R. S., Department of Geology, Portland, Oregon
MEACHAM, Chuck, Alaska Department of Fish and Game, Wrengell, Alaska
MEEHAN, W. R., Alaska Department of Fish and Game, Juneau, Alaska
PARKER, R. R., Alaska Department of Fish and Game, Juneau, Alaska
PERRY, L. E., U. S. Bureau of Commercial Fisheries, Portland, Oregon
PHINNE7, H. K., Oregon State College, Corvallis, Oregon
POLIFKA, J. G., Soil Conservation Service, Portland, Oregon
RAYNER, H. J., Oregon Game Commission, Portland, Oregon
REED, W,, Journal, Portland, Oregon
RULIFSON, R. L., Oregon Fish Commission, Portland, Oregon
SALMON, W. E., Pacific Power and Light, Portland, Oregon
SANTOS, J. F., U. S. Geological Survey, Portland, Oregon
SPIES, K. II., Oregon State Sanitary Authority, Portland, Oregon
STEIN, J. E., Rayonier Marine Lab., Hoods Canal, Washington
TERHUNE, L. B. D., Fishery Research Board of Canada, Nanaimo, B. C.
WAGNER, R., Washington Pollution Control Commission, Olympia, Wash.
WATSON, D. G., General Electric Company, Richland, Washington
WEST, R. M., U. S. Forest Service, Portland, Oregon
WICKETT, W. P., Fishery Research Board of Canada, Nanaimo, B. C.
WILSON, J. N., Public Health Service, Portland, Oregon
WOELKE, C. E., Washington Dept. of Fisheries, Quilcene, Wash.
SIEB3LL, Chuck, Washington Pollution Control Comm., Olycpia, Wash.
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