Project Brief: Fish Screens for Yakima Streams. Page: 2 of 4
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with the new technology, screens would block young fish, not irrigation water.
The Problem
The Yakima valley gets very little rain - only
about seven inches per year. The lifeblood of the
Yakima valley -- "Fruitbowl of the Nation" - is
irrigation water from the Yakima River and its
tributaries. Since the 1800s, Yakima valley
farmers have used irrigation ditches to bring that
precious river water to their fields.
But at the same time, irrigation ditches were
contributing to losses in salmon and steelhead
runs. Yakima's adult fish runs - once estimated
at over a half million fish - had dropped to
barely a few thousand.
At first, flat metal screens were put in irrigation
ditches to keep migrating fish in the stream. But
debris clogged these screens, blocking the flow of
water to crops and fields.
Later, rotating drum screens were installed. But
often they were set perpendicular to the stream
flow and the screen mesh was too big. The
screens killed some fish on impact or allowed
smaller ones to pass through and become
stranded in fields. And they had to be cleaned
and lubricated practically every day.The Solution
In 1982, the Northwest Power Planning
Council approved measures for restoring fish runs
in the Yakima Basin. The goal was challenging:
to save fish without reducing irrigation water
flows.
The task involved BPA, the U.S. Bureau of
Reclamation, National Marine Fisheries Service,
U.S. Fish and Wildlife Service, Washington
departments of Fisheries, Wildlife and Ecology,
Yakima Indian Nation, Bureau of Indian Affairs
and Yakima irrigation districts.
They formed a technical work group to study
the problem. After many years of cooperation
and creativity, they came up with a new concept
in fish screens. They used the new idea at major
irrigation diversions such as Sunnyside and
Toppenish. This was called the Phase I fish screen
project.
Biologists found the new screens kept out 99
percent of the fish without affecting irrigation
water. They also discovered the concept worked
well for smaller creeks.
In 1988, WDF used the new screen concept at
Brewer ditch, a small irrigation ditch near Naches,Wash. The success of this prototype became the
basis for beginning Phase II of the fish screen
project in 1989.
Phase II plans to replace about 60 old screens
with the new screen technology. The screens
would be built at sites along the Yakima, Naches,
Teanaway and Tieton Rivers, and at other
locations in the Yakima Basin. BPA and
Reclamation would pay for the work. They
estimate Phase II would cost about $12 million.
Reclamation and BPA representatives are now
studying the project and talking to landowners.
Washington Department of Fisheries would do the
work. Phase II construction could begin in 1991
and finish in 1995.
Fabrication and Installation
Fish screens would be built by the Washington
Department of Fisheries at their screen shop in
Yakima. WDF workers would make the screens
from a 1/8inch stainless steel wire mesh. This is
small enough to keep young fish from passing
through. Workers would wrap and weld mesh
into a drum around a steel frame. The steel iscoated with epoxy to prevent corrosion. Each
screen would be made to fit the stream where it
would sit.
The power to rotate the screen and keep it
dean would come from either an electric motor
or a new, high-tech paddlewheel developed by
the WDF screen shop.
WDF, BPA and Reclamation would talk to
landowners to arrange replacing old screens with
new. The diameter, length and number of screens
per ditch would vary depending on the amount of
water diverted.
The Bureau would build the concrete
foundation and related works. WDF would install
the screens. Workers would install screens as
close to the head of the canal as possible to keep
out trash and sediment. They would schedule the
work at the landowner's convenience and would
keep the number of machines and crew working
on the landowner's property to a minimum. Most
screen construction would take place in the
winter months-outside of the irrigation season.
WDF and Reclamation would take care of
raising screens out of canals at the end of each
irrigation season.-i 4
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United States. Bonneville Power Administration. Project Brief: Fish Screens for Yakima Streams., report, September 1, 1990; Portland, Oregon. (https://digital.library.unt.edu/ark:/67531/metadc900205/m1/2/: accessed March 28, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.