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5. Alternate No 3. • This fish ladder is located on the right abutment of the diversion dam and features include a fish trap, louver for fish protec- tion, a new sluice gate, auxiliary attraction water supply, and bar screen at the headgates. This alternate is cost effective as compared to Alternates No. 1 and No. lA because of lower .costs associated with earth excavation instead of concrete removal through the existing dam struc- ture. However, a majority of the fish may not be attracted away from the main channel flow to this right bank fish ladder. The design and con- struction costs of this alternate are $575,100. 6. Alternate No. 4. This fishway is located through the left bank of the river into the existing power canal. Fishway features include a fish trap, a collection channel, auxiliary attraction water supply, a circular baffled flume fishway, louver in the power canal, and trash shear boom. This baffled flume fishway does not have enough supporting evidence that it will pass the two target species. Also, the fishway does not have flex i- bility to adjust fishway velocities if it is not effective. The design and construction costs for this alternate are $512,500. 6. Conclusions. Fish entrance location is one of the most important parameters in determining the success of a fish passage facility. Alternates No. 1, No. lA, and No. 2 all have the preferred biological entrance location. Alternate No. 3, however, would attempt to modify the identified fish behavior and attract the fish away from the existing channel. The poten- tial risk associated with this alternate was judged large enough to outweigh the identified cost savings. Alternate No. 4 also has a poor entrance location, but not as unfavorable as Alternate No. 3. However, the inflexibility associated with the circular baffled flume ladder is not a reasonable risk considering the uncertainty in the biological criteria. Alternate No. 2 was eliminated from consideration because of the uncertainty that the experimental ladder would supply the needed inforrnation. The additional cost of $550,000 to make a fully functional ladder and the complications resulting from a second construction season were also considered. Alternates No, 1 and No. lA are biologically similar. There- f ore, Alternate No. lA is recommended for design and construction because of its lower initial construction cost. However, if final design reveals • 36