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is U.5 fps. The drop in water surface at the fishway entrance is regu- • laced by side-opening slide gates across the entrances. e. Grating over the trap will be included for initial security measures, 2. Description of Standard Operation. a. The American Fishways "baffled flume" ladder is designed to carry 24 cfs. The ladder and collection channel are placed so that a minimum of 3 feet of flow depth will occur throughout the fishway at low tailwater. The average velocity in the ladder is 2 to 3 fps with peak velocity at the baffle of 12 to 15 fps. b. At higher flows, a backwater effect will occur into the collection channel and the ladder. The collection channel will be func- tional until tailwater reaches elevation 4,567.0 feet, which corresponds to approximately 8,000 cfs of riverflow. For riverflows above 8,000 cfs, the collection channe] will be overtopped by water and the fishway will not be functional, c. Auxiliary water is added below the ladder itself to provide attraction water at the entrances. The total quantity of available auxiliary water is three times the ladder flow, or 72 cfs. With two entrance gates operating at one time, the flow conditions are similar to the other alternates. With the 96 cfs total flow, the collection channel flow and flow near the diffuser have a velocity of approximately 3 fps. 3. Operational Flexibility. This particular ladder does not allow any operational flexibility within the ladder structure. The ability to adjust entrance openings, the number of entrances open, and the amount of auxiliary water in the collection channel provide flexibility of operation. 4. Other Considerations. a. Biological and Technical Considerations. (1) These fishways have had some success in passing fish that are "moderately strong swimmers." However, this alternate does not allow any adjustments within the fishway to accommodate weaker species. 32 •