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I ~ 1-..-.-. .:\ it' ~i ~! ~.....f...~..., it'" . !l, : " I ". ~.i -- t\ ~. ~~ f I 'I J .. ~ f ; I '. " > , ,- ~~ :~\. :\i " '.~ . ~" 'i-. WATER SUPPLY AND DEVELOPMENT OF IRRIGATICN r'- t"'.. The U. S. Bureau of Reclamation Closed Basin Report 1/ states: ":";''''l CJ ,~.~ ' '-_J Water Resources The water resources of the Valley are derived mainly fran sncMfall on that portion of the drainage area above 8,000 feet in elevation. Precipitation on the Valley fl=r, which averages about 7 inches per year, augments the supply to a small extent. Exclusive of this precipitation on the Valley fl=r, the water supply averaged about 1,466,400 acre-feet per year for the period 1936 through 1959 and was available as follCMs in the various parts of the Valley: Stream Rio Grande near Del Norte Conejos River Basin West Side Tributaries East Side Tributaries Closed Basin Percent of Total 41 23 10 8 18 Total 100 The recent Geological Survey Report Y on the San Luis Valley .states: Discharge of water fram the valley averages about 2,000,000 acre-feet per year by evapotranspiration and about 500,000 acre-feet per year as flCM a=oss the State line. The stream flCM at the State line averages 445,000 a=e-feet and ground water underflCM ac=unts for a small arrount =rently esti- mated at 55,000 a=e-feet.... In 1967 there were about 2,800 wells in the San Luis Valley that yielded nore than 300 gallons each. Of this total, 2,160 tap the un=nfined a<XjUifer ... In addition to the large capacity wells, there are nore than 7,000 small capacity flCMing wells '" Ground water withdrawal for recent years (1962-1967) averaged about 1,100,000 acre-feet per year.... The Rio Grande fan contains much nore ground water today than it did before the beginning of i=igation. About 1900, the water table was reported as 50 to 100 feet belCM land surface. . . . Y See reference 18 Y See reference 27 3