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. . " ... . . GVWM Flow Protection Plan December 19, 1994 4:02pm DRAFT The Manager Emeritus of the Grand Valley Water User's Association, Mr. Bill Klapwyk, has had roughly 40 years experience with the Grand Valley Project system. Through this experience Mr. Klapwyk has found that after the irrigation demand begins to subside, it usually takes about 400 to 450 cfs in the canal system to be able to meet all of the delivery elevations along the canal. The timing of this decreased demand varies from about the fIrst of September up to the third week in September. Again, based upon experience, late season demand usually falls to around 200 to 250 cfs, but can fall to as low as 150 cfs. So theoretically it may be possible to conserve up to 300 cfs (450-150). (It may not be possible to maintain the desired water surface elevation at a flow of 150 cfs, or it may prove too costly to do so. In addition, it is not generally advisable to decrease canal diversions to exactly meet demand because of the uncertainties in weather and demand.) For the purpose of estimating the possible amount of conserved water, use 100 cfs reduction in diversion requirements starting September 1 and then increase the amount conserved to 200 cfs on September 15 and carry this amount through November 1. The resulting quantity of water \ \ r\ conserved is approximately 33,000 af. ~ -\ The effect of Colorado River runoff volume on Green Mountain Reservoir stora!!e tarl!ets - "n ()/ \~ From the period 1965 to 1990 there was an average of approximately 48,000 af in the HUP on 1\lw ~, November 1. In 1989 the HUP was depleted which correlates well with the large direct releases I tl' I to the 730 cfs right. If water conservation measures could have been implemented in that year c:'~{f!' ." .' it would have been possible to keep above the HUP targets and enhance flows in the 15-Mile J! Reach. In 1990 the November 1 HUP storage volume was about 4,000 af and releases to the ( 730 cfs right were 14,985 af (using the old method of computing consumptive use). A more ~~\ (W complete analysis of November 1 stora~e volumes and direct release computations will be . (Mff'~""", necessary, but if 1990 is an indication, . the actual releases to the 730 cfs right are clqsr~~ t "~ ~/ the estimated 26,665 af, and lit a November 1 target of about 4,000 af is reasonable" t6en 11 ~ 'r) . appears that GMR HUP targets may restrict the reallocation to about 26,665 af on a fIrm yield! ~ ~ Summary The two factors whic~ontrol the ability to reallocate GMR HUP and ultimately increase flows in the 15-Mile ReacH; 1) the ability to conserve, and, 2) the ability to keep GMR HUP above targets. These factors appear to have a good fIt for most years. In dry years, such as a 1977 water year, water conservation may only be used to keep the GMR HUP at storage target levels. But even in relatively dry years such as 1989, conservation and reallocation would benefIt both GMR HUP and 15-Mile Reach flows. Of course, all of this is contingent on the ability to establish targets on the GMR HUP, to declare excess, and then make industrial releases to the Grand Valley Power Plant. 24 ~(I I I/'/ -Ik. ~ se /"; wA,;';{ If /s /' I" -l d l<2fo/'t. :z- Ti/U:! " ~ /. / j,/es 01" t"~f. e.e,~ee (2'~e.t'"'!I a.. 0>0 / -I I- :r-f /?eea'S .~ I . c.vr1tfe.nU ;JaA'- -10 I~:~/: o/' "i-;:::S- ~ ""'- sn>oo.Jk...-11ra.-ns' "",,--fo --It:' ~ ""'1"F'~l< //J a- I . u/r"-<- >".."....s.' ~" t$VUlur1Sy.s: e>r>_ "