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.. !)03H'j fI' CRAPrER I PLANS OF DEVELOFME:NT The project lands under this plan would lie at an average elevation of 6,700 feet. In view of the cl:lmatic conditions and the type of farm- ing and crop yields that could be expected in the area, the total aver- age annual equivalent irrigation benefits would probably not exceed .$45 an acre. A comparison of this benefit with the cost gives a benefit- cost ratio of about .6 to 1 for Plan A. Because of this unfavorable benefit-cost ratio, detailed investigations of the plan are not justi- fied. Shiprock Project as a Base for D- and E-Series Plans The D. and E-series plans are considered as potentialities for the South fun Juan project, but physioally and economically they should be viewed as extensions of the potential Shiprock project. Each of the alternative plans would share in the use of the storage and diversion facilities of the Shiprock project, and each would irrigate lands east of or higher than lands planned to be irrigated by the Shiprock proj- ect. For an understanding of the D- and E-series plans, therefore, some knowledge of the Shiprock project plan is necessary. . River regulation for the Shiprock project would be provided by the Navajo Reservoir on the fun Juan River. The reservoir would be formed by a dam at the Navajo site about 19.5 river miles upstream from Blanco, N. Mex., and 34 miles east of Farmington, N. Mex. The dam would be about 3.5 miles downstream from the confluence of the Pine and fun Juan Rivers. The acreage of the potential Shiprock project has not been finally determined but it has been studied in sizes of 100,000, 113,900, and 121,700 acres. The plans for each of these three different sizes of Shiprock project have been used as bases in the com- parative analyses of the various plans for the South fun Juan project as presented in this report. Navajo Dam and Reservoir data for the Shiprock project alone are summarized in the following table. Shiprock project acrea e 100,000 113,900 121,700 Table IV SHIPROCK PROJECT NAVAJO DAM AND RESERVOIR DATA Reservoir ca cit -- Acre-feet Silt storage above dead st ora e 20 ,000 209,000 210,000 Reservoir water surface elevat ion Norna 1 Dead 5,957 5,7 3 5,968 5,775 5,976 5,782 Active st ora 21 ,000 280,000 322,000 . 6