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. <0 00 ~ ...... . . HISTORY OF WATER RESOURCE DEVELOPMENT (Continued) Storage %r~ect Reservoirs) was estimated to be about 150,000 acre-feet (185 x 10 m ) per year. Water exported from the Upper Basi?!; ~uring the period 1941-70 averaged about 360,000 acre-feet (440 x 10 m ) per year. Completion of the large projects such as the Colorado-Big Thompson, Duchesne Tunnel, Roberts Tunnel, and the more recent projects such as the San Juan-Chama Fryingpan-Arkansas, Homestake and partially completed Strawberry Aqueduct 6r3sulted in increased diversions to about 700,000 acre-feet (863 x 10 m ) in 1976. Reservoir evaporation varies from year-to-year but the variations have little effect on average streamflow depletions. For the period of record considered, average reservoir evaporation in the Upper Basin was not large until about 1963 when the Colorado River Storage Project Res- ergo~r started to store water, In 1975 about 653,000 acre-feet (805 x 106m3) were evaporated from the reservoirs and about 678,000 (836 x 10 m ) in 1976. Under normal operating conditions, evaporation from the Colorado River Storage Pr<1;iEf,t reservoirs is expected to average about 568,000 acre-feet (701 x 10 m ) annually. In the Lower Basin, water is diverted to municipal and industrial projects and to irrigation districts. These M&I projects include the Southern Nevada Water Project which diverts water from Lake Mead above Hoover Dam, and the Metropolitan Water District which diverts water from above Parker Dam and exports it to the Southern California coastal areas. Below Parker Dam water is diverted for irrigation to the Colo- rado River Indian Reservation and to the Palo Verde Irrigation District. At Imperial Dam the water is divided into three parts. On the left it irrigates the Gila and Yuma Projects, on the right it goes to the Imperial and Coachella water districts through the All American canal, with the remaining water going to Mexico. Below the Imperial Dam, water is delivered to Mexico as required by the treaty with Mexico. There is essentially no flow below Morelos Diversion Dam except for the bypassed saline flows from the Wellton-Mohawk Drain Extension. C. Legal Aspects, Water Quantity 1. Colorado River Compact Water of the Colorado River was divided between the Upper and Lower Colorado River Basins by the Colorado River Compact which was signed in 1922 by a commissioner of each of the seven States of the river basin and by a representative of the United States, All States but Arizona ratified the compact prior to its effective date in 1929. The dividing point on the river between the Upper and Lower Basins is at Lee Ferry wbich is defined as a point 1 mile (1.6 km) below the mouth of the Paria River. (Not to be confused with Lees Ferry which is the site of the gaging station just above the Paria River.) The compact apportions from 13