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• louver and trash boom from the upstream end of the ladder to the left <br />bank. <br />C. Selection of Final Alternatives. <br />1. The nine preliminary alternates were evaluated at the <br />scoping meeting and four alternates were selected for further study. The <br />other five alternates were rejected due to poor location with respect to <br />the swimming routes of migrating fish, adverse impacts on RWPC, difficult <br />construction or operation of the fishway, and excessive construction <br />and/or operation costs. <br />2. Alternate F, Ladder Through Spillway Crest Adjacent to <br />Sluice Gates. <br />a. This alternate was selected to provide flexible ladder <br />operation. The head drop per pool could be varied from 1/4-foot to 1 <br />foot with a vertical slot/orifice ladder. The ladder would be "stacked" <br />downstream and the fishway exit would extend at least 20 feet upstream. <br />This location of the exit would reduce fish fallback over the spillway. <br />b. This particular configuration of the fish ladder has <br />several advantages. The majority of construction would take place on the <br />downstream side of the dam during the low flow period of the year. <br />Cofferdam construction and RWPC lost power revenues will be minimized as <br />a result. <br />3. Alternate A, Experimental Ladder. <br />The short, experimental ladder would test if the target <br />species fish will enter and climb a vertical slot/orifice fish ladder. <br />This alternate could be constructed so that a "full-size" ladder could be <br />added to it if testing proved successful. An advantage of this alternate <br />is low-cost construction of a test facility before a large amount of <br />money is committed to the full-size prototype model. <br />4. Alternate B, Right Abutment Ladder. <br />a. This alternate provides the same operational flexibility <br />as Alternate F. This ladder would also be "stacked," as is Alternate F, <br />but the majority of the structure would be on land and not in the river. <br />Instead of a siphon pipe for attraction flows, a sluice gate has been <br />added within the spillway. This modification to Alternate B was adopted <br />from Alternate G. <br />• <br />9 <br />