Laserfiche WebLink
7 <br /> project is 465.649 MAF, divided by 34 years which equals 13.695 MAF; this flow <br /> less Compact and Mexican Treaty deliveries equals 5.446 MAF. This final number <br /> represents Upper Basin depletions assuming no shortages. If an average shortage <br /> of 6.11 percent is assumed (2.1 MAF of M&I uses with no shortage and 3.7 MAP of <br /> irrigation with an average shortage of 10 percent), we divide 5.446 MAF by 93.89 <br /> percent which gives the 5.8 MAF Upper Basin possible depletion. <br /> The effect of sediment accumulation in Lake Powell was also evaluated. <br /> Preliminary Planning studies indicate that the total 100 year volume of accumu- <br /> lated sediment in Lake Powell would be 8.54 MAF, 3.9 MAF of which would be <br /> expected to deposit above the minimum power pool . Consideration of this volume <br /> of sediment in the above equation changes the computed depletion by only 2 per- <br /> cent. • <br /> There are two different hydrology data sets available that were used with the <br /> formula to evaluate and verify the present 5.8 MAF determination. The hydrology <br /> data sets are used with the formula to determine average streamflow and the cri- <br /> tical period. These are discussed below: <br /> 1 . Virgin Flows - Virgin flows are computed, undepleted flows at Lee Ferry. <br /> They are available on an annual basis for the period 1896 to 1981 . <br /> 2. Colorado River Simulation System (CRSS) Natural Flows - these are also com- <br /> puted, unregulated, undepleted flows at Lees Ferry. They are computed on a <br /> monthly basis taking into consideration Bureau and non-Bureau reservoirs, trans- <br /> basin diversions and imports, municipal and industrial uses, and depletions from <br /> consumptive use computed by the modified Blaney-Criddle method. While monthly <br /> natural flows have been determined for 19 stations in the Upper Basin for use in • <br />