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<br />. <br /> <br />l-& <br />o <br />... <br />CoO <br /> <br />. <br /> <br />.1 <br /> <br />HISTORY OF WATER RESOURCE DEVELOPMENT (continued) <br /> <br />projects such as the Colorado-Big Thompson, Duchesne Tunnel, Roberts <br />Tunnel, and the more recent projects such as the San Juan-Chama, Fryingpan- <br />Arkansas, Homestake, and partially completed Strawberry Aqueduct resulted <br />in increased exports to about B48,000 acre-feet (1046 x 106m3) in <br />1978. <br /> <br />Reservoir evaporation varies from year to year but the variations <br />have little effect on average streamflow depletions. For the period of <br />record considered, average reservoir evaporation in the Upper Basin was not <br />large until about 1963 when the Colorado River Storage Project reservoirs <br />started to store water. In 1975 about 653,000 acre-feet (805 x 106m3) <br />were evaporated from the reservoirs and about 690,000 (851 x 106m3) in <br />1978. Under normal operating conditions, evaporation from the Colorado <br />River Storage Project reservoirs plus Navajo and Fontenelle is expected to <br />average about 568,000 acre-feet (701 x 106m3) annually. <br /> <br />In the Lower Basin, water ~s diverted to municipal and industrial <br />projects and to irrigation districts. These M&I projects include the <br />Southern Nevada Water Project which diverts water from Lake Mead above <br />Hoover Dam, and the Metropolitan Water District which diverts water from <br />above Parker Dam and exports it to the Southern California coastal areas. <br />Below Parker Dam water is diverted for irrigation to the Colorado River <br />Indian Reservation and to the Palo Verde Irrigation District. At Imperial <br />Dam the water is divided into three parts. To the east it irrigates the <br />Gila and Yuma Projects, and on the west it flows to the Imperial and <br />Coachella water districts through the All-American Canal, with the remain- <br />ing water going to Mexico. Below the Imperial Dam, water is delivered to <br />Mexico as required by the treaty with Mexico. There is essentially no flow <br />below Morelos Diversion Dam except for the bypassed saline flows from the <br />Wellton-Mohawk Drain Extension. <br /> <br />C. Legal Aspects, Water Quantity <br /> <br />1. Colorado River Compact <br /> <br />Water of the Colorado River was divided between the Upper and Lower <br />Colorado River Basins by the Colorado River Compact which was signed in <br />1922 by a commissioner of each of the seven States of the river basin and <br />by a representative of the United States. All States but Arizona ratified <br />the compact prior to its effective date in 1929. The dividing point on the <br />river between the Upper and Lower Basins is at Lee Ferry which is defined <br />as a point 1 mile (1.2 km) below the mouth of the Paria River. (Lee Ferry <br />is not to be confused with Lees Ferry which is the site of the gaging sta- <br />tion just above the Paria River.) The compact apportions from the Colorado <br />River system to each of the Upper and Lower Basins in perpetuity for exclu- <br />sive beneficial consumptive use, a total of 7.5 million acre-feet (9300 x <br />106m3) annually. In addition to the apportionment of 7.5 million acre- <br />feet (9300 x 106m3), the Lower Basin is given the right to increase its <br />beneficial consumptive use of water from the Colorado River system by 1 <br />million acre-feet (1000 x 106m3) annually. The compact further prov- <br />ides that the States of the upper division will not cause the flow of the <br />river at Lee Ferry to be depleted below an aggregate of 75 million acre- <br />feet (93 000 x 106m3) for any period of 10 consecutive years. <br /> <br />13 <br />