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2321 " Spilhlay.--A gated spillway of 170,000 cfs capacity "ould be located on the right ebutment. Foundation material "ould be sandstone and shale. The inflow design flood has a peak of 437,700 cfs and a 20-day volume of 1,363,000 acre-feet. Outlet Works. --A combined outlet lIorlrs ~Iould e;lso be located on the right abutment \-There shale is available for fotU'ldation. Delivery capacities from the outlet \larks "lOuld be as follows: 4 ,000 cfs to the river; WO cfs to Bijou Canal on the right abutment; and If20 c?s to the Riverside Canal on the left abutment. Relases to both canals ,muld be siphoned under the spillway. Full releases to both cErl als and the river would be at a minimum lIater surface elevation of 4,522 feet or '1I1en the water surface is at the bottom of the conservation pool. "", Riverside Canal.--About 6 miles of new canal having a capacity of If20 cfs lIould be required. This canal "ould originate at the outlet worlts on the ric;ht abutment and would be carried under the spilh'BJ' and river in a siphon. After emerging from the siphon, it would extend along the north side of the ri vcr to connect '.'ith the e;risting Riverside Canal below the pl'esent reservoir, The attached drawing #553-730-3 shows the location of the proposed Weld County Reservoir. '~r ECONOHIC ANALYSIS General Comparison of the relative advantages or disadvantages of the potential Narrows and Weld County sites involves analysis of costs, and benefits accruing during the useful life of the worlrs. Under the Bureau of Reclamation procedures of analysis this period is teJ,en as 100 years. Hydrologic and operation studies have not progressed to the point \-mere conclusions Day be dralltl concerning annual water yield from the reservoirs; however, it is possible to make sorre raui!P evaluations af annual benefits associated ,lith the potential watcr st~lies by use of data contained in the Narrows Report of 1951. '. Tr~ Corps of Engineers has recently provided reconnaissance flood control benefit data for the two sites. No current information is available relative to benefits for fish and "ildlife, recreation, or stream pollution abateIrent, nor have any costs been added to provide for these functions. The tenefi ts, accruing from these functions, h01<ever, are expected to be less important than zither flood control or irrigation. This analysis also omits any evaluation of losses or costs arisins from intmdation of productive reservoir lands, although construction cost estiDlates do include amounts for 13