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0017HQ The CRSP model inflows for the Parker to the Imperial reach accounted for only a small amount of water salvage due to past phreatophyte removal, and none in the future. The net effect was to reduce average annual reach loss by only 12,000 af. Thus, the difference in estimates of water saved from reduction in phreatophyte consumptive use accounts for a major part of the hydrologic difference in the Parker to the Imperial reach. The difference of 293,000 af cited in the summary table would have been even greater had the CRSP average reach loss been based on data that included the 1935-1962 period. The reach below Imperial Dam is not a source of additional water in CRSS. Since CRSS does not employ any hydrology data downstream of the Imperial Dam, inflow is zero. The CRSP data showed an average of 162,000 af of inflow per year in this reach. When the CRSS data base is completed for this reach, we may expect it to be a "gaining reach," that is, a source of additional water. 2. Mechanisms in CRSS which Enable More Water to Reach Lake Mead and Then be Delivered to CAP a. "602a" Storage Determination. In CRSS, the study used for this comparison simulated the "602a" storage requirement by determining what amount of Upper Basin storage would be required to deliver 8.23 million acre-feet (maf) per year to the Lower Basin over a reoccurrence of the 12-year drought period of 1953 through 1964, while still maintaining a minimum generating head at the Glen Canyon Dam. Projected depletions and sediment accumulations are considered in making the determination. The CRSP study used for comparison did not equalize storage at all after 1993 because the estimation of "602a" storage exceeded the total storage capacity of the Upper Basin reservoirs after 1993. The CRSS study has occurrences of storage equalization releases throughout the study. Some of the "storage equalization" releases would have to be spilled eventually anyway, but they are undoubtedly a mechanism which, on the average, releases more water into Lake Mead in the CRSS study. b. Criteria for Determination of Water Shortage Situations. The CRSP study reduced CAP diversions to 400,000 af per year when Lake Mead fell below 1124 feet. CRSS reduced CAP diversions to 450,000 af per year when Lake Mead fell below 1095 feet. This difference in decision criteria enabled a full supply to be delivered to Arizona more frequently when using the CRSS model. When shortages did occur, CRSS delivered 50,000 af more. 1124 10"/5 - ) 3,752. R ..-\"J p"", e,.. ~e"d II, c> <>"'0 I ~ I A1"..e. (Y);,.'\;""\A,I'W'V rJ 70,,\ 000 Cl..~, -", I 4 ~ d' v' 1/-'-"J '0 1),'(- 0'0" ","" r1-~ ~\'" '7e- f'o..u e.'f"J poo