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<br />e;, <br /> <br />second-feet. Its first 3-mile section would include a tunnel 1,204 <br />feet long and a siphon 2,404 feet long across Largo Canyon, an inter- <br />mittent tributary of the San Juan River. About 7 miles below the diver- <br />sion dam a 22-foot drop in the canal would be utilized to propel a tur- <br />bine-driven direct-connected pump that would lift part of the water 49 <br />feet to the East and West Highline laterals. The East Highline lateral <br />would be 3.8 miles in length and would have an initial capacity of 6 <br />second-feet. The West Highline lateral would be 2.9 miles in length <br />and would have an initial capacity of 13 second-feet. Smaller distribu- <br />tion laterals would be constructed as needed throughout the project area. <br />A drainage system also would be installed to prevent low lands from being <br />waterlogged with seepage from higher, more permeable lande. <br /> <br />The potential South San Juan project and the Shiprock project (In- <br />dian) would divert water from the San Juan River at the Navajo Reser- <br />voir site located 15 miles upstream from the Hammond Diveraion Dam. <br />The Navajo Reservoir ia planned aa a feature of the Colorado River stor- <br />age project. The main canal for the South San Juan and Shiprock pro- <br />jects could also convey water to Hammond project lands, making unneces- <br />sary the Hammond Diveraion r:e.m, the upper section of the Main Gravity <br />Canal, including the tunnel and siphon and possibly the hydraulic pump <br />lift. If either the South San Juan or Shiprock project is authorized <br />prior to construction of the HalllDlond project, the desirability of aup- <br />plying Hammond project lands f~om the higher ca.nal ehould be investigated. <br /> <br />Water Supply <br /> <br />The San Juan River is the only perennial stream in the Hammond <br />area. It ia fed primarily from melting snows in the San Juan Mountains <br />of southwestern Colorado. Most of its run-off occurs as spring floods <br />in May and June. After June run-off decreases rapidly and is lowest <br />late in July and August. <br /> <br />Diversion requirements for the irrigation of project lands are ex- <br />pected to average about 18,400 acre-feet annually or about 5 acre-feet <br />an acre properly distributed throughout the irrigation season. These <br />requirements could be fully met from natural flows of the San Juan River <br />in years of normal run-off. Detailed water supply atudies made over the <br />1931-1940 drought period show that shortages would occur only in the late <br />sUlllDler in years of extremely low run-off. With unregulated flow condi- <br />tions a maximum annual shortage of approximately 20 percent could be ex- <br />pected in an extreme drought year such as 1934. Probable shortE-.ges would <br />be reduced or eliminated if the Navajo Reservoir is built to regulate the <br />San Juan River flow. <br /> <br />The Hammond project would deplete the flow of the Colorado River by <br />about 7,900 acre-feet annually and thus would utilize only a amall por- <br />tion of the water allocated New Mexico by the Upper Colorado River Com- <br />pact. The project would have no effect on present uaes of river water <br />and would not materially interfere with potential projects in the San Juan <br /> <br />3 <br />