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r~ b. Impacts. (1) Impacts Affecting RWPC. (a) To attain desirable fish attraction condi- tions, RWPC may be asked to slightly modify their standard operating pro- cedures. During high spring flows, releases of flow through the existing sluice gates should be regulated for the best fish attraction conditions. Flow from the sluice gates should not create a velocity barrier at the west fish entrance during the migration season. Also, as flashboards are installed on the dam crest, their placement should start at the right bank (looking downstream) and progress toward the left bank. This should keep the attraction flow, created by spilling of water over the crest, near the fish ladder. (b) Bar screen may be installed across all four power canal headgates. The head loss through the screens is approximately 0.2 foot with all gates fully open. This bar screen will not be installed until it is determined that the ladder successfully passes fish into the f orebay. (c) The ladder structure blocks a portion of the spillway that would normally pass riverflows. Therefore, sediment may accumulate behind the diversion dam in the ladder area. RWPC may be asked to open the sluice gates for the purpose of flushing accumulated sediment from behind the dam. (d) Construction of the fish ladder will only have minor impacts on RWPC. The bar screen installation, if necessary, would be scheduled to coincide with the dewatering of the power canal for maintenance. Also, the upstream cofferdam can be constructed around the ladder structure only, and not interfere with the power generation and irrigation flows into the power canal. However, this alternate would require two construction seasons if the full-size ladder was added. (e) RWPC will be asked to continue their efforts for removing trash at the dam. (2) Impacts Affecting FWS. (a) FWS will operate and maintain the fishway facility. This alternate will require that fish be released from the trap periodically (check trap every day during migration season), weir boards be installed or removed, flow valves and entrance slide gates be • adjusted, and debris be removed from the fish ladder trashrack. 25