|
<br />COLORADO RIVER STORAGE PROJ,ECT
<br />
<br />13
<br />
<br />At a point 15 miles below Glen Canyon Dam site, the Paria River
<br />contributes an avemge of about 25,000 acre-feet annually to the
<br />Colorado River, but the flow is erratic from year to year. For all
<br />practical purposes the flow at Glen Canyon approximates the flow at
<br />Lee Ferry, 16 miles downstream, the dividing point on the river
<br />between the upper and lower basins, The ave,rage annual virgin flow
<br />at Lee Ferry over t,hc 1914-45 period is estimated at about 15,640,000
<br />acre-feet, "
<br />STREAM DEPLETIONS
<br />
<br />Annual man-made depletions in the Upper Colomdo River Basin
<br />from existing develoJlments and developments authorized prior to
<br />1949, the year the lJpper Colorado River Basin compact became
<br />effective, o,re estimated to average abont 2,550,000 acre-feet. A
<br />number, <;>f years will be requiJ:ed for full development of projects
<br />l\uthoo'ized prior to 1949, The 2,550,000-acre-foot depletion is
<br />therefore used in this report as also applying to fiscal year .1963, when
<br />initial opemtion of the stomge project is scheduled and is also referred
<br />to as the present depletion. On the basis of the annual depletion of
<br />2,550,000 acre-feet, the upper basin is ut.ilizing only about one-third
<br />of the consulllptive use apportioned to it by the Colorado River
<br />compact,
<br />As a basis for evaluating the Colorado River storage project and
<br />pltl'ticipatjn~ projects; a projection was made of future stream de-
<br />pletions est,lmnted to occ,ur in the upper basin dming the 100-year
<br />period from fiscal year 1963 through fiscal year 2062. It was estimated
<br />that ,the depletions by 2062 would total about 6,191,000 acre-feet
<br />aimually, consisting of 2,550,000 acre-feet from existmg development:;,
<br />691,000 acre-feet fron,\ evaporation from the authorized storage'units,
<br />and 2,950,000 acre-feet fmm new project,s including the authorized
<br />part.icipating projects ltnd other futme Federal ltnd non-Federal
<br />developments, The 2,950,000-acre-foot depletion from new projects
<br />exprossed ltS a weighted average amount over the 100-yeltr period
<br />approximates 1,800,000 acre-feet, It figlU'e used hereinafter in the
<br />pr<;>iect economic anltlysis. Assumed average depletions are summar-
<br />iz8d in (,he tltble below.
<br />Projected depleUQns I
<br />
<br />lIn thousand 8cre--feet]
<br />
<br /> Depll\tlon Average
<br /> lromo.~isti.ng eVill)orntlon
<br />FISCllI~eRr IUldnew 10llsesfrom Tota.l
<br />pmJe.n:sln stOtd~ ualts ~
<br /> npper bnslD.
<br />19t13.__........._____.____________.________.._____...u________ 2,550 N(\gllgible 2,560
<br />1m_.__....____..___________________________________.________ 3,160 691 3,841
<br />.2OIlO...._____..______.__________._._________.__________________ 11,750 60' 0,441
<br />.2(W'I~-..---..----..------.. ----- _______.__.__________u________ 5,000 691 6,191
<br />
<br />I Based on overages for runolJ period 1914 to 1945, Inelusl va.
<br />~ Estimated average stream dopl"tlons due to evaporation {rom Olen Cnnyon, Flaming Gorge, Navaho,
<br />and Curccantl storng(l, units.
<br />
<br />REPLACEMENT STORAGE
<br />
<br />The, holdover rosel'voirs in the Upper Colorado River Basin ltre
<br />designed (,0 impowld' water in yoltJ.s of high runoff and release such
<br />wa(,el' during prolonged dry periods to permit the upper bltSin to
<br />
|