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<br />The graphs on pa~l')5 ?7 flnd 28 illu5trate some of the pertinent histoncal fads
<br />related to the amounts of wah:)r produced by the Colorado River System above l.ee Ferry,
<br />Nilonfl, the compact division point between ttH~ Upper and l.ower Colorado River Basins,
<br />TIll') first graph, on par~e 27, is entitled Colorado RivElr Flow at L.tlO Ferry, Arizona The lop
<br />of each veriieal bar represents the estimated virgin flow of the river, i.e" the flow 01 th~l
<br />riv~1r in millions of acre-teet pasl L.ee Ferry tor a given year had it not boen depleted by
<br />activities of man, Each vmtical bar has two compollents: The lower shaded part
<br />r~)pl'C~sellls tho ~1stimated or measumd historic flow at Lee F'crry, and thEl differE:HlGo
<br />bdwt,en the two sections of tho har ill any given Yflar repmsents the strclalTl d()plc~tiol\, ()I'
<br />tho amount of watm estimated to have bepn removed by man Irom thn virgin supply
<br />upstl'(Jall1 from Lc(~ Forry, It is wOlih noting that in 1977, Cllld again in 1981, the historic
<br />floW at l.ee F0rry eXGoeded th~1 virgin flow, Beginning in 1 B!32, part of this depldion elt LeE)
<br />FHrry was caus!3d by thE) retention and storage of water in storage units of the Colorado
<br />Riv(~r Storage Project The horizontal line (at approximately 15,0 million acre-feet) show5
<br />the long-term average virgin flow fron, 1 B96 lhrou~h 2001, BecaUSt1 the Colorado I~iver
<br />Compact is adrninisterod on the basis of running averages covering periods of ten yeals
<br />the proqrc~SiVl) ten..year aVEm~gt~ historic a virgin flows are displayed on ttlis grap
<br />
<br />~
<br />
<br />tit
<br />
<br />Lee Ferry Average Annual Flow fo
<br />historic and virgin flow aVma!~(lS lor
<br />sE~lm.:h1d w(~re thoSEl to which
<br />)erta !J 10 the Coloradc:
<br />
<br />y(~ars
<br />doculTllmls
<br />
<br />second graph on page) 28, entitled
<br />is a graphical repr0selltCition of
<br />· record The p~m()ds of waleI'
<br />y made various purpo~;l?!,; i
<br />
<br />Ih
<br />Solected Periods
<br />llriods 0,
<br />Jsua
<br />
<br />Sf.lvm<l
<br />refermlGfl is
<br />Rivm Systc~rr
<br />
<br />pages
<br />
<br />on
<br />
<br />hf~5e tWC) grapns
<br />
<br />ppal'lmt from
<br />
<br />nportant hydrologiC facts are
<br />
<br />SCNera
<br />21 and ?8
<br />
<br />9/.9
<br />
<br />1924-1933 decad(.~, tile progressiv~, ten-year average virgin flow has not
<br />th~) average virgin flow except in the 1941-1950 and the exceptionally
<br />!H5-1984 thl'()ugh 1984-1993 decades
<br />
<br />tit
<br />
<br />is estimated
<br />gage on the
<br />
<br />For the period 1896-1921, which is prior to the Colorado River Compact of 192?,
<br />the average VIrgin flow WilS estimated to be 16,8 million acre-feet per year, which
<br />is considerably greater than for any other period selected, including th010ng-.term
<br />average, A strcam"gaging station at Lees Ferry, Arizona was not installed I
<br />1921 Thus, the virgin flow at Lees Ferry prior to the 1922 Compact
<br />based upon records obtained at other stations, e,g, the stream
<br />Colorado River at Yuma, Arizona for the period 1902"1.~2,1,
<br />:......'~ I~ , '
<br />
<br />3
<br />
<br />For the longest period shown, 1896.2001, the estimated average annual virgin
<br />flow is 15,0 million acrefnet and the average annual historic flow IS 12 million
<br />aCI'l?-feet.
<br />
<br />(4
<br />
<br />For the next longest period, 1906-2001, the estimated average annual virgin flow
<br />is 15,1 million acre-feet and the average annual historic flow is 12,0 million
<br />acre-feet. Many of the early records for this series of years, as well as for the
<br />1896-2001 period, are based upon the estimates of flows made at other gaging
<br />stations, as mentioned in (3) above, This average is about equal to the 15.0
<br />million acre-feet estimated for the 1906-1967 period which was used as the basis
<br />
<br />25
<br />
<br />prior to
<br />
<br />occurred
<br />
<br />flows
<br />
<br />majority of the high
<br />
<br />811lce ttH~
<br />exceeded
<br />we'
<br />
<br />5
<br />
<br />^ vast
<br />
<br />?
<br />
<br />'F'Jrog,.(,~~~iVt1 -.
<br />10Year
<br />Total
<br />(1 ,ogo oJ.>...."
<br />
<br />!l!l,990
<br />93,1()~;
<br />90.D16
<br />93,544
<br />92,664
<br />1l3,148
<br />77,246
<br />79,340
<br />78,8:i6
<br />1l0,'l6!)
<br />'15,:i09
<br />82,930
<br />88,780
<br />87.2Hl
<br />87,843
<br />88,288
<br />88,299
<br />87.182
<br />90,044
<br />89,'l53
<br />88,746
<br />96,125
<br />108,366
<br />118.20,....
<br />126,5'13
<br />131,754
<br />131,545
<br />131,207
<br />128,382
<br />128,198
<br />127,898
<br />118,515
<br />106,303
<br />96.436
<br />91,100
<br />91,507
<br />96,791
<br />100,224
<br />101,650
<br />101,880
<br />
<br />1 ani,.. 4
<br />
<br />FLOW AT LEE FERRY
<br />1953-2001
<br />"""" . ""
<br />
<br />962,
<br />
<br />rovision
<br />
<br />Storogo in Flaming Gorgo and Navajo Roservoir!; began in
<br />Storago in Glen Canyon Reservoir bogan in 1963,
<br />Storago in Fontonello rosorvoir bogan in 1964,
<br />"Based upon provisional streamflow records subjoct
<br />
<br />to
<br />
<br />24
<br />
<br />I:>toric
<br />now
<br />OOOu
<br />
<br />.f.)
<br />
<br />/.l,am)
<br />(i'lll)
<br />7,30'1
<br />8,1(")0
<br />'17,340
<br />'14,;160
<br />0,"156
<br />H,HI2
<br />0,n74
<br />'14,'790
<br />2,l)20
<br />2,427
<br />10,8:\ti
<br />7,870
<br />1,!l24
<br />(1,358
<br />n,050
<br />a,(j88
<br />13,1307
<br />~),3:JO
<br />10.141
<br />8,277
<br />!J,2'14
<br />B,494
<br />!l,:1.(l9
<br />8,:169
<br />8,333
<br />10,9!)Q
<br />8,316
<br />8,323
<br />17,520
<br />20,518
<br />19,109
<br />16,866
<br />~,450
<br />tl,160
<br />7,995
<br />8,125
<br />8,132
<br />8,023
<br />8,137
<br />8,306
<br />,9,242
<br />11 ,~j30
<br />13,857
<br />13,444
<br />11 ,428
<br />9,551
<br />8,362
<br />
<br />HISTORIC
<br />
<br />WotorYm
<br />Ending
<br />(~Ol?,1. :\9
<br />
<br />'1!;)5:i
<br />1954
<br />19!)!)
<br />1956
<br />19!j'(
<br />1958
<br />I 95!,)
<br />1960
<br />1961
<br />1962
<br />196:i
<br />1964
<br />1~165
<br />1966
<br />1967
<br />196!l
<br />'190fl
<br />1970
<br />'19'11
<br />HI??
<br />1973
<br />1974
<br />19'15
<br />H)i'S
<br />1977
<br />19/8
<br />1979
<br />Hl80
<br />19AI
<br />1982
<br />1983
<br />1984
<br />'1985
<br />1986
<br />1987
<br />1988
<br />1989
<br />1990
<br />1991
<br />1992
<br />1993
<br />1994
<br />1995
<br />1996
<br />1997
<br />1998
<br />1999
<br />2000
<br />"2001
<br />
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