January 14, 1965
Mr. Owen W. Hurd, Managing
Director
Washington Public Power Supply System
P.O. Box 672
Kennewick, Washington
Dear Mr. Hurd:
This letter is a commentary on certain aspects of proposed
changes in lake level and the drop structure at Packwood Lake. It has been prepared
at the request of Mr. S. K. Billingsley. The comments will represent my
professional opinions based on approximately 30 years experience with many
diverse kinds of fishery investigations. I hold B.S. and Ph.D. degrees from
Cornell University where I majored in Fisheries Biology. I have been the
Director of the Fisheries Research Institute at the University of Washington
since 1958. Prior to that time I was employed as a Fishery Research Biologist
by the U.S. Bureau of Commercial Fisheries for 16 years with headquarters
successively in Cambridge, Massachusetts, New Bedford, Massachusetts, Woods
Hole, Massachusetts, Honolulu, Hawaii, and Juneau, Alaska. In Juneau, Alaska, I
was Assistant Regional Director in charge of research. Prior to working for the
Bureau of Commercial Fisheries I was employed by the Conservation Department of
the State of New York and by Cornell University in investigations of trout and
warm water fishes.
Effect of Opening Drop
Structure to Permit Release of up to 300 cfs During Flood Water Periods on
Escape of Fish
The
species of fish of concern in Packwood Lake is rainbow trout which has been
resident there for many years. Substantial populations have existed because the
lake is reported to have provided good angling and records of the Washington
Department of Game show that as many as 3,021,000 eggs were taken artificially
from the trout in Packwood Lake. This would mean that approximately 1,500 adult
females were stripped. If we assume that these were accompanied by an equal number
of males it would appear that spawning grounds in the lake tributaries
supported at least 3,000 adult fish at the time these spawn-taking operations
were under way.
These
populations persisted in the lake despite the regular annual floods down the
outlet creek. Within a few hundred yards of the lake the creek bed is so
precipitous that no fish can migrate up to the lake. It seems clear that this
stock of fish is non-migratory and did not tend to leave the lake under natural
conditions in numbers which seriously reduced the populations. In my judgment,
they would be no more apt to leave the lake through an opening in the drop
structure.
Effect of Submerged
Trees on Fish Habitat
Unquestionably
the dead trees which have fallen in the lake around the shores have benefited
the fish. The tangle of limbs provides important habitat for young fish where
they can escape from their larger relatives and the debris encourages the
growth of fish food organisms. Somewhat similar brush shelters have been
artificially provided in a number of lakes in order to enhance the environment
for fish.
Effect of Reduced Lake
Level During Spawning Season on Access to Spawning Streams
The
rainbow trout ascend the tributary streams of Packwood Lake during May and June
to spawn. During the spawn-taking operations which were conducted by the
Washington Department of Game from 1933 to 1940 they were captured by weirs
from 10 to 100 yards above the mouths of the streams. The State records show
that during most of these years eyed eggs were shipped to other hatcheries from
the Packwood station between June 12 and July 27. These probably had been held
in the Packwood station for about one month before they were eyed and sturdy
enough to ship, and hence it appears that the spawn-taking operations occurred
from early May to the latter part of June which would correspond approximately
to the spawning period.
The
normal level of the lake has been considered to be about 2855 feet. The maximum
high water attained under natural conditions was about 2858.5. Usually the lake
was near its normal level during the first month of the year and then commonly
rose to maxima during May, June and July. Then usually the level decreased with
only occasional high water conditions during late autumn or early winter.
Under
the conditions of operation by the licensee it is expected that lake level may
be reduced to a minimum of 2850.5 during the fall and winter and I understand
from Mr. Billingsley that during recent months the lake occasionally has been
down to this level.
With
low lake levels and flood water conditions in the streams it may be expected
that the streams will cut channels down to lake level which are entirely
comparable to the channels they occupy immediately above the highest water
mark. One need look no further than at the intertidal channels of streams which
empty into the ocean to see that this is almost always the case. It should be
extremely simple to observe whether this is the case at Packwood Lake and in a
remote chance that a stream is spread out in a fashion which makes it difficult
for fish to ascend it should be simple to start a channel cutting through the
stream delta in a few hours by one man with a hand shovel.
I
note further from the U.S.G.S. gauge records for the years 1960-63 that the minimum
levels during May and June varied between 5.70 and 5.93 and the maxima between
6.88 and 7.68. Thus it was normal for the lake to vary in level during these
two months between 1 and 1.7 feet.
In
summary, I believe that it is highly unlikely that changes in lake level during
May and June would in any way interfere with access to the spawning streams. If
by remote chance it does it could be easily observed and easily corrected.
Sincerely
yours,
WFR:ac
