After the Washington Department of Fish and Wildlife (WDFW), Yakima Screen Shop (YSS), has completed the installation of your rotary wiper - flat plate fish screen, operation and maintenance (O&M) becomes the responsibility of the diversion owner under state law (RCW 77.55.040 (formerly RCW 75.20.040); RCW 77.55.070 (formerly RCW 75.20.061)). The following discussion describes routine O&M necessary to: 1) insure that juvenile fish are adequately protected from entrainment in the ditch and injury at the screen, and 2) insure reliable operation and long life of the screen facility components, thus reducing annual O&M costs.

OPERATIONAL REQUIREMENTS

The screen must be operated with proper submergence (range: 65% - 85% of screen height; 80% optimal) to keep water velocity through the screen equal to or less than the 0.4 feet per second (fps) approach velocity criteria established by the National Marine Fisheries Service (NMFS) and WDFW. The approach velocity criteria has been established to prevent salmon, steelhead, trout and whitefish fry from becoming impinged (involuntarily immobilized ) on the screen. A bypass flow is required at all times, but especially from spring start-up (April-May) until the end of smolt migration (typically by June 30). Bypass flows after this critical time may be reduced (but not totally eliminated) to adjust for declining instream flow. Please contact the YSS screen inspector for your area or call the YSS for guidance on proper bypass operation.

OPERATION PROCEDURES

When the YSS installed the fish screen, the screen location was selected to insure that there is adequate elevation drop between your point-of-diversion (POD) and the screen site. Consequently, the screen will not inhibit the normal flow of water to your irrigation canal, when running at the required submergence level (see above).

1. Open the diversion headgate until you estimate that the diverted flow is about 10 -15 percent greater than the consumptive demand. The additional water is for fish screen bypass and screen cleaner operation and will be returned to the creek or river.


2. Adjust the check boards behind the screen at the downstream guides to keep the water level on the screen between the min. and max. lines painted on the screen structure (this provides proper screen submergence). Double wiper (shallow installation) screens have a screen height of 12 inches; the minimum water depth is 8 inches (65%). Single wiper (deep installation) screens have a screen height of 24 inches; the minimum wse is 16 inches (65%). Rotary wiper speed should be between 4 to 6 rpm. Adjust rotation speed by adding or removing check boards in the fish bypass entrance. Proper operation will normally require a ½ inch undershot and the normal 4 - 6 inch spill over the bypass check boards. The cleaning system (rotary wiper brush) is designed to operate using the flow through the bypass slot and will not operate (clean properly) without sufficient bypass flow.


3. Adjust the check boards in the fish bypass entrance so that the extra water diverted in Step 1 spills to provide fish passage back to the river. Check the bypass outfall at the river to see that it is unobstructed and free flowing. Normal spring bypass flow should be 4 - 6 inch spill over the boards. The bypass check boards should be removed once or twice a week for 10 - 15 minutes to flush sediment from in front of the screen.


4. After setting fish bypass flow, re-adjust the headgate, as needed, to achieve the desired ditch flow downstream of the fish screen. If you experience any problems or have questions, please contact your local YSS screen inspector or Pat Schille at the YSS at 509-575-2735.

MAINTENANCE

PRE-SEASON

1. Inspect screen and paddlewheel cleaner components for wear, breakage or vandalism.


2. Inspect the perforated plate screen for damage or any openings greater than 3/32 inch ( maximum allowable opening, NMFS and WDFW criteria ).


3. Lube all bearings (any multi-purpose grease).


4. Check the rotary wiper brushes for wear and alignment, repair and adjust as needed (Note: brush contact with the screen surface should be light pressure to prevent excessive friction and stoppage).

IN-SEASON

1. Lube bearings monthly (any multi-purpose grease).


2. Remove debris from in front of screen, off cleaner brushes and in bypass slot.


3. Adjust check boards in bypass slot for proper rotary wiper operation (rotational speed).

POST-SEASON

1. Remove all check boards from the fish bypass to allow headgate leakage to return to the river.


2. If there is no diversion headgate, install check boards in the slots provided in front of the screen structure to isolate the screen from the river to prevent flood damage. Secure the site to protect it from other damage (e.g. falling trees, vandalism, etc.).