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<br />,.,..' r'1 <br />.J .; 1 ~.1 <br /> <br />CHAPTER 4 <br /> <br />j <br /> <br />\ <br /> <br />HYDROGRAPHY <br /> <br />COLORADO RIVER AND COLORADO RIVER AQUEDUCT <br /> <br />COOPERATION was continued in 1951-1952 with the U. S. <br />Geological Survey. as in previous years since 1935, in secur- <br />ing adequate and accurate runoff and other stream gaging <br />records on the lower Colorado River and its tributaries. Valuable <br />and much appreciated help is also acknowledged in the form of <br />weekly and monthly J"i,'er operation and evaporation reports of the <br />U. S. Bureau of Reclamation; climatological and runoff forecast <br />reports of the U. S. Weather Bureau and the Soil Conservation <br />Service; and numerous other reports of Federal, state and county <br />organizations on hydrographic data for Southem California or <br />the Colorado River. <br />Using preliminary unpublished data of the U. S. Geological <br />Survey, subject to later slight revisions, the discharge of the <br />Colorado River at Lee Ferry (the Compact division point between <br />the upper and lower basins) for the "water year" ending September <br />30, 1952, was 17,970,000 acre-feet. This is about 8,150,000 acre- <br />feet, or 83 per cent more than for the preceding ,'ear, being the <br />highest runoff in the last 23 years and has been exceeded in only <br />one of the Jast 31.years. The 1952 runoff is 77 per cent above the <br />average for the severe drouth decade ]931-40 and is four times the <br />flow in the 1934 minimum year of record. <br />The season's runoff is 133 per cent of the long-time mean dis- <br />charge of about 13.500,000 aere-feet at Lee Ferry (with present <br />upstream depletion) for the period 1905-1951. This "available" <br />flow is derived by supplementing the record since 1922 with the <br />U. S. Bureau of Reclamation and U. S. Geological Survey runoff <br />estimates for earlier years (based on records at other Colorado <br />River gaging station;;) and then adjusting for present increases iu <br />past upstream depletions, by lIleans of the Reclamation Bmeau's <br />studies and eomputations. <br />Iucluding measured tributary side inflow and also unmeasured <br />gains, combined with the observed flow of the Colorado River at <br />the Grand Canyon gaging station (tentative record, subject to <br /> <br />[58 ] <br /> <br />I <br />, <br />