7316

• UCREFRP Catalog Number: 7316
• Author: U.S. Army Corps of Engineers.
• Title: Redlands Dam Fishway Feasibility Study, Gunnison River, Colorado.
• USFW Year: 1986.
• USFW - Doc Type: Walla Walla.
• Copyright Material: NO

•
b. The fishway exit area is large enough to accommodate an
8-foot-wide, 8-foot-long, 5-foot-high trap. The fish are guided into the
trap through V-shaped notches in the trap structure that fit the vertical
slot and orifice openings. Fish easily find their way into the trap but
do not easily find their way out through the notches. The trap allows
for exiting or trapping of fish by means of an upstream gate. The down-
stream end of the notch can be closed and the fish can be crowded to the
water surface for observation or tagging. Fish can also be removed from
the ladder, while being contained in the trap, by means of a hoist on the
work platform,
c. This alternate provides vertical bar screens upstream
from the headgates to prevent migrating fish from entering the power
canal, if necessary. A trash shear boom is also provided to reduce
debris problems at the fish ladder and screens.
d. The ladder also has provisions for auxiliary attraction
water supply at the fish entrances. Water enters from the forebay
through a trashrack located near the sluice gates and is piped to the
diffuser. A valve is provided at the diffuser to adjust the quantity of
attraction water. The maximum velocity into the trashrack and from the
diffuser is 0.5 fps. The drop in water surface at the fishway entrances
is regulated by side-opening slide gates across the entrance openings
adjacent to the diffuser.
e. Security fencing will be installed-across the west side
of the sluice gate area. Also, grating will be installed to cover the
fish trap and provide access over the ladder, For additional security
measures, provisions for future grating installation will be made to
cover the entire ladder, if necessary.
2. Description of Standard Operation.
a. The vertical placement of the fish ladder entrances and
exit accommodates low flow conditions as well as higher flows. A minimum
3-foot water depth i s desired i n the entrance pool and al 1 1 adder pool s
during normal operation. From preliminary tailwater computations, low
tailwater was calculated as elevation 4,563.0 feet. This elevation was
based on a reasonable design low flow of 300 cfs, which is 50-percentile
expected flow for August. The fish ladder entrance was then set at
4,560.0 feet elevation to maintain a 3-foot minimum pool depth. Using
the low tailwater elevation and an upstream water surface elevation of
4,575.0 feet, the change in water surface elevation from below to above
Redlands Diversion Dam is approximately 12 feet. The upstream water
• level of 4,575.0 feet elevation is the desired minimum water depth main-
tained by RWPC. The basic design of the ladder uses the biological and
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