7845

• UCREFRP Catalog Number: 7845
• Author: Miller, W. J. and D. Laiho.
• Title: Final Report, Upper Colorado River Basin Recovery Implementation Program, Feasibility Evaluation Of Non-Native Fish Control Structures.
• USFW Year: 1997.
• USFW - Doc Type: \
• Copyright Material: NO

1
(100 percent efficiency) downstream migration of adult fish, fish larvae; and fish eggs, because all
life stages of undesirable fish species would be present during some part of the project operating
season and they could not be controlled discriminately. The basic criteria were that the fish control
system must be capable of handling the maximum canal discharge of 1,950 cfs and not be cost
prohibitive.
A fixed horizontal screen sloping slightly downward was chosen as the best available technology.
Prior to this application, fixed horizontal screens had not been used to filter fish larvae or eggs. Most
applications were used to filter weed seeds from irrigation water, collect water biological samples
from a small stream, and filter industrial intake water. Most systems were small with capacities of
less than 100 cfs. Because of the uniqueness of the McCluskey Canal screening concept in both
design capacity and efficiency, a long-term costly testing program was implemented. Both
laboratory and field testing were conducted on all aspects of the concept, from design to operation
and maintenance.
The proposed McCluskey Canal fish screen facility was designed to handle 1,000 cfs with a modular
design which was divided into 6 bays of which 4 would be operational, while 2 remained available
for standby. Each bay would be subdivided into 14 subbays that could be operated independently.
One subbay would contain 4 upper and 4 lower screen panels. The total facility would contain 84
subbays with a total of 672 screen panels. The proposed indoor facility, including shop and
personnel areas, would cover more than 2.5 acres. Following is a discussion of the major
components of the facilities in the order that they are encountered in the system.
Coarse debris would be removed by trash racks placed at the entrance to the screening facility that
would have a 1-1/2 inch bar space opening. Debris would be removed from the upstream face of the
trashracks by a mechanical trash rake. A conveyor would transfer the debris to a disposal bin for
temporary storage. Flow into each bay of the facility would be controlled by a rapid-closing, top
sealing radial gate. Adjustable blade weirs would be used to control flow into each subbay, while
stop logs would be used to shut off the flow completely. Screened water follows the outlet channels
located underneath the screen panels back to the main McCluskey canal. 'Each subbay would contain
four upper and four lower 3- by 12-foot, 70-mesh (0.198 mm), screen panels. The lower panels
provided a backup system in case the top screens or seals are damaged. The screens were set at a 5°
downslope in the field test facility based on laboratory tests which indicated this slope would be
optimum for both self cleaning and hydraulic efficiency. In the laboratory, as the screen slope was
increased, self cleaning action improved as a result of the water velocities increasing across the
screen surface. This is desirable for self cleaning, but requires a much longer screen to pass the
design flow. Water-activated cleaning methods would be needed rather than mechanical which
could damage the screen. During field testing, other slopes and design flow rates were evaluated.
Increasing the flow from the design flow of 6 cfs per lineal foot of weir for the test facility to 20 cfs
per lineal foot and decreasing the slope from 5° to 2°, resulted in a reduction of backwashing
frequency by one-half. The design flow rate for the screening facility would be 1.5 cfs per lineal foot
of weir as opposed to 6 cfs per lineal foot for the test facility.
r A traveling screen was installed at the test facility to determine if prescreening would remove the
plankton load that in turn would allow a higher flow rate through the sloping screens. It was not
found to be beneficial during testing, but provisions were recommended in the facility design to
install a traveling prescreen if the situation was justified.

Control Structure Feasibility Evaluation 1-29
Miller Ecological Consultants, Inc., February 18, 1997