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I I I I I I I I I I I I I I I I I I I 6.2.2 Elevations The invert elevations of the ladder are set as described in Alternative I. Flow characteristics in the ladder for the range of design river flows are calculated in conjunction with the hydraulic analysis of the alternative presented in Section VII. Table 7.2 summarizes the results. 6.2.3 Attractive Flow The intake for the attractive flow pipe is located downstream from the fish ladder exit by 60 feet primarily as a function of alignment as discussed above. Distance between the intake and the fish ladder are maintained at 50 feet as discussed in Alternative I. The intake design includes a screen for trash and debris. 6.2.4 Access Access to the fish ladder is needed from the east side as described in Alternative I. 6.3 Alternative III Fish passage for Alternative III is depicted on Drawing 4 in Appendix A. This alternative includes dam reconstruction and channel regrading to accommodate both fish and boat passage. In this alternative, boulders and concrete cutoff walls are utilized in conjunction with alterations to the existing dam to create two sequences of chutes and plunge pools. The upstream cutoff wall is created by utilizing the existing dam. A low flow notch is cut into the structure 1.5 feet deep by 50 feet wide. This notch is designed for boaters and fish by insuring surface flow through the chutes during low flows. The top of the existing dam is capped to create a gentle slope from the low flow notch up to the channel banks. Both the upstream and downstream faces of the dam are backfilled with riprap. The upstream backfill is to protect the structure from debris and to protect boaters from the structure. Downstream riprap serves to provide a continuous bed from the top of the dam, into the plunge pool. The second chute consists of a concrete cutoff wall with the same general shape and dimensions 28