|
<br />,
<br />
<br />i
<br />I
<br />I
<br />
<br />.~ Af ~ .~.
<br />4J...i......
<br />
<br />WATER SUPPLY AND REQUIREMENTS
<br />
<br />';
<br />
<br />Streamflaw and Storage
<br />
<br />The staff continued its collection of basic data
<br />on watet supply and use, estimates of unmeas-
<br />ured items and projections of all items affecting
<br />the water budget of Colorado River. Data in this
<br />section are reponcd for the water year from
<br />October 1, 1966, through September 30, 1967.
<br />The /low of Colorado River at Lee Ferrv dur-
<br />ing the water year was 7,782,000 acre-feet.
<br />Adjusted for changes in surface storage in the
<br />Colorado River Storage Project reseervoirs, the
<br />quantity becomes 8,327,000 acre-feet. The Bu-
<br />reau of Reclamation estimates that if there had
<br />been no upstream man-made depletions the vir-
<br />gin /low at Lee Ferry would have been approxi-
<br />matclv 11,700,000 acrc-fcct. For comparison the
<br />estimated annual average undepleted or virgin
<br />/low was 13.7 million acre-feet during the 1922-
<br />67 period of record and 14,8 million acre-feet
<br />during the 1896-1967 period, Plate 4 shows esti-
<br />mated annual virgin flows at Lee Ferry since
<br />1896,
<br />Climatological data early in the 1966-67 water
<br />year gave indications of high runoff of the Colo-
<br />rado River. However, the prospect of having
<br />two succcssive years with below average flows
<br />was assured by an extremely dry spring in the
<br />major contributing areas of the basin. The Janu-
<br />ary 1967 forecast of the Bureau of Reclamation
<br />predicted an April-Jul~' inflow to Lake Powell
<br />of 10,000,000 acre-feet, bur succeeding forecasts
<br />were drasticallv reduced, and the actual runoff
<br />during April-July 1967 was only 6,045,000 acre-
<br />feet.
<br />Table 2 summarizes the Bureau of Reclama-
<br />tion forecasts of the 1967 April-July inflow to
<br />Lake Powell.
<br />Measured flows at the three upstream stations
<br />which account for approximately 95 percent of
<br />the inflow to Lake Powell were all less than
<br />average, Regulated releases below Hoover Dam
<br />were limited to the amounts necessary to meet
<br />consumptive use requirements in the United
<br />States and the obligations to Mexico.
<br />Flows at key points in the basin for water year
<br />1966-67 are shown in Table 3.
<br />
<br />1
<br />
<br />t
<br />
<br />j
<br />
<br />~
<br />
<br />f,
<br />
<br />I
<br />
<br />I
<br />
<br />Table 2
<br />
<br />U,S. BUREAU OF RECLAMATION FORECASTS OF
<br />APRIL-JULY RUNOFF INTO LAKE POWELL
<br />
<br />Mton ForuQst
<br />Altan FortcQst. % oj AtJtragef % of
<br />196i FoucaJts as of {.-lcrt-fat} 1906-1966 Actual Runoff
<br />
<br />January L________
<br />February L __ _ _ ___
<br />March L__________
<br />April L___________
<br />May L___________
<br />June L___________
<br />
<br />1O,0CNl,<XXl
<br />9,900,000
<br />8,800,000
<br />6,300,000
<br />5,100,000
<br />5,700,0CK)
<br />
<br />165
<br />163
<br />145
<br />1M
<br />84
<br />94
<br />
<br />119
<br />118
<br />105
<br />75
<br />61
<br />68
<br />
<br />. Alluming no regulation by major reluvoin upltream.
<br />t U.S.B.R. enimate of average April-July historic inAowl to Lake Powell for
<br />the 1906-1966 period i~ 8,500,o:xJ acre-feet.
<br />
<br />Table 3
<br />
<br />MEASURED FlOW IN COlORADO RIVER
<br />BASIN FOR WATER YEAR 1966-67
<br />
<br />(Thousands 01 Acre-Ieet)
<br />
<br />Statioll
<br />
<br /> M~aJurrd Flow
<br /> AdjUJud for Chang~
<br /> in Surfac~ Storag~
<br />M~afurrd AdjUft~d %of
<br />Flo~() Flow ..Jvtragtf
<br />3,059 3,298 63
<br />3,963 4,215 100
<br />934 1,051 59
<br />7,956 8,564
<br />7,809 8,354-. 71
<br />8,257 8,802. 74
<br />7,832 81
<br />7,941 83
<br />6,407 74
<br />1,566 45
<br />
<br />Uppu Rafin
<br />Green R. @ Green River (Utah)
<br />Colorado R. @Cisco(Utah)___
<br />San Juan R. @ Bluff (Utah)_ __
<br />
<br />SubtotaL. _ _ _ _ _ _ _ _ _ __ ____
<br />
<br />Colorado R. at Lee Ferry________
<br />Lou:tr BaJin-Colorado R.
<br />Near Grand Canyon__________
<br />Below Hoover Dam___________
<br />Below Davis Dam____________
<br />Below Parker Dam_______.___
<br />Flow into Mexico_____________
<br />
<br />. It is ellimated that about JJ2,UO acre-feel wn absorbed in Lake Po....ell bank
<br />.!Crage during the water year 1966-67.
<br />1 The averagei for the itUlOnl upltream from Hoover Dam reprelent the 1922-
<br />67 period which i, the lenKth of record ilt Lee ferry. The llverail:e, lor Hoover
<br />Dam ;;lnd downltream nation, reprelenlthe 1950-65 period which il the length
<br />01 record al Davi. Dam.
<br />
<br />Article III (d) of the Colorado River Com-
<br />pact provides that the States of the Upper Divi-
<br />sion will not cause the /low of the river at Lee
<br />F err)' to be depleted below an aggregate of 75,-
<br />000,000 acre-feet for any period of ten consecu-
<br />tive years, In the past five years the accumulation
<br />of storage in the Colorado River Storage Project
<br />
<br />27
<br />
|