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• ladder flow from the junction pool to each fish entrance. The entrance <br />diffusers add water to provide better fish attraction conditions. The <br />total quantity of auxiliary water available is three times the ladder <br />flow quantity. Since the ladder flow exit is split into two separate <br />legs, each entrance slide gate passes one-half of the combined ladder <br />and auxiliary waterflows. The width of the slide gate opening and amount <br />of auxiliary flow can be adjusted to attain the desired head drop at the <br />entrance. <br />3. Operational Flexibility. <br />a. The number of fish ladder weirs can be reduced to 11 <br />weirs, which form 8-foot- by 20-foot-long pools. The result of this <br />modified design is a 1-foot head drop per pool. For this operational <br />condition, the total ladder flow is approximately 25 cfs and the <br />available auxiliary flow is 75 cfs. At high riverflows (6,000 cfs), the <br />head drop will gradually vary from 0.35 foot at the downstream end of the <br />ladder to 1.0 foot at the upstream end of the ladder and ladder flow will <br />be 28 cfs . <br />b. The number of fish ladder weirs can also be increased <br />to 45 weirs, which form 8-foot-wide by 5-foot-long pools. The result of <br />this modified design is an approximate head drop of 0.25 to 0.35 foot per <br />pool. For this operational condition, the total ladder flow is approxi- <br />mately 15 cfs and the available auxiliary flow is still 75 cfs. At high <br />riverflows, the head drop will gradually vary from 0.10 foot at .the <br />downstream end of the ladder to 0.25 foot at the upstream end of the <br />ladder and the ladder flow will be 16 cfs. <br />c. Refer to Table 1 for ladder flows, slot and orifice <br />velocities, and head drop per pool. <br />4. Other Considerations. <br />a. Biological and Technical Considerations. <br />(1) The two target species prefer swimming close to <br />the river bottom. At the fishway entrances, fish can remain near the <br />river bottom and swim through the side-opening slide gates. These gates <br />can be adjusted to achieve the desired head drop at the entrance and the <br />gate opening will be flush with the invert elevation of the entrance at <br />4,560.0 feet. <br />(2) The fish ladder is positioned so that fish migrat- <br />• ing up the main channel of the river will be attracted to the sluice <br />gate discharge. These fish would most likely locate the west entrance. <br />13 <br />