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OOHi5~ are derived from basic apportionments, existing contracts, and infor- mation supplied by the three Lower Basin States. The diversions needed to meet the consumptive use of demands with return flows are ca 1 cul ated from ei ther hi stori ca 1 di vers i on to con- sumptive use ratios, maximum diversion capacity to maximum allowable consumptive use ratios, or an assumed diversion to consumptive use ratio of approximately 167 percent when no other data are available. For exports, or demands where no return flows are assumed, the di ver- sion is set equal to the consumptive use. Other water uses not pro- jected in the above consumptive use report, such as phreatophyte consumptive use and diversions to water quality improvement projects, are estimated. Evaporation from Lower Basin reservoirs are not included in the demand data base since evaporation is simulated in. the modeling process. Monthly percentage values are calculated from historical data or from average monthly percentage values of similar demands if no other data are available. The monthly percentage values for State of Nevada demands were supplied directly for use in the CRSS by the Colorado River Commission of Nevada. Salt pickup data for individual irrigation project return flows are scarce in the Lower Basin. A value of salt pickup is provided for two projects: the Palo Verde Irrigation District and the Colorado River Indian Reservation. These values were determined from Reclamation project data. Salt pickup from other irrigation projects is accounted for in the salt gains and losses values in the hydrology data base. The delivery of water to Mexico is included in the data base as a Lower Basin demand. The diversion is the amount specified by the Mexican Water Treaty of 1.5 million acre~feet per year plus an esti- mated 1 percent additional water for unavoidable overdeliveries of 15,000 acre-feet per year. 4.4 Demand Data Output The SMDID program can generate several reports when it creates the demand data input file from the demand data base. The reports summarize the data contained in the demand data base. Report 1 summarizes the data at the user level. Withdrawal, depletion, return flow, and salt pickup data are displayed for each user for the years specified in the input file. Totals are accumulated for each demand point and reach. Salt pickup accumulation for a demand point is weighted proportionally to the individual user return flow in mgfL. Report 2 summarizes the data at the reach level. The withdrawals, depletions, return flows, and salt pickup are displayed for each reach broken down for each of the nine uses (thermal power; agriculture; fish, wil dl ife, and recreati on; mi nera 1 s; 1 i vestock and stockpond evaporati on; 16