Southwest Hydrology: The Resource of Semi-Arid Hydrology Volume 4 Number 2

Home Browse Search

eo" ri< PI /lP/ dmw de,`Jfi%rr, <rrP /�� / /i� / /6�va &?, Colorado River Compact of 1922 • Divides the Colorado River, including all tributaries, into an Upper and Lower Basin, with the boundary between them at Lee Ferry, Arizona. • The "Lower Division" states are Nevada, California, and Arizona, and the "Upper Division" states are Wyoming, Colorado, New Mexico, and Utah. • Arizona, Utah, and New Mexico have lands within both basins. Significant hydrologic stipulations in Article III of the Compact: III(a) "There is hereby apportioned ... in perpetuity to the Upper Basin and to the Lower Basin, respectively, the exclusive beneficial consumptive use of 7,500,000 acre -feet of water per annum ... " III(b) "In addition to ... paragraph (a), the Lower Basin is hereby given the right to increase its beneficial consumptive use ... by one million acre -feet per annum." lll(c) "[Water to Mexico] shall be supplied first from the waters which are surplus over and above the aggregate of the quantities specified in paragraphs (a) and (b); and if ... insufficient ... the burden ... shall be equally borne by the Upper Basin and the Lower Basin, and ... the Upper Division shall deliver at Lee Ferry water to supply one -half of the deficiency ... in addition to that provided in paragraph (d)." III(d) "The States of the Upper Division will not cause the flow ... at Lee Ferry to be depleted below an aggregate of 75,000,000 acre - feet for any period of ten consecutive years ... " Boulder Canyon Project Act of 1928 Authorized Hoover Dam and Lower Basin irrigation facilities, including the All American Canal. • Apportioned the Lower Basin's annual 7.5 million acre -feet (maf) among the states of Arizona (2.8 maf), California (4.4 maf), and Nevada (0.3 maf). • Arizona received exclusive beneficial use of the Gila River and its tributaries in addition to its 2.8 maf allocation. Mexican Treaty of 1944 Committed delivery of 1.5 maf per year from the United States to Mexico. United States may reduce deliveries during an "extraordinary drought" proportional to reductions in U.S. consumptive uses. Upper Colorado River Basin Compact of 1948 • Apportioned the Upper Basin's annual 7.5 maf (or what remains after the Upper Basin meets its obligations at Lee Ferry): 51.75 percent to Colorado, 23 percent to Utah, 14 percent to Wyoming, 11.25 percent to New Mexico, and 50,000 acre -feet per year to Arizona. 1963 and 1964 Arizona v. California U.S. Supreme Court Decisions In 1963, the Supreme Court ruled that Lower Basin states have the right to appropriate and use tributary flows, and that such use does not constitute use of a states Colorado River apportionment.This settled a 25 -year dispute in which California claimed that Arizona's use of water from the Gila River, a tributary to the Colorado River, should be counted against its Colorado River apportionment. • In 1964, the Supreme Court issued a decree enjoining the Secretary of the Interior from delivering water outside the framework of the apportionments defined by the law and mandated the preparation of annual reports documenting the uses of water in the three Lower Basin states. • The 1964 decree specified apportionments to five Indian reservations totaling about 900,000 acre -feet per year. The Colorado River Basin Project Act of 1968 • Authorized construction of the Central Arizona Project and other water development projects in the Upper and Lower basins. • Assigned lower priority to the CAP apportionment than California's apportionment. Criteria for Coordinated Long -Range Operation of Colorado River Reservoirs of 1970 • Provided for the coordinated operation of reservoirs in the Upper and Lower basins and set conditions for water releases, including "equalization releases," from Lake Powell and Lake Mead. Colorado River Quantification Settlement Agreement of 2003 • California agrees to reduce its over - reliance on Colorado River water and to live within its authorized annual share of 4.4 maf by 2017. March /April 2005 • Southwest Hydrology • 19