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<br />000731
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<br />over 61 million acre-feet - more than four times the River's annual average flow. More than a third of
<br />the River's supply is exported from the Basin, and some 2 million acre-feet of water is lost in evaporation
<br />each year. Approximately 80 percent ofthe River's supply is used for agriculture.
<br />
<br />While the large reservoirs in the United States were initially filled, virtually no fresh water reached the
<br />Gulf of California. Today, the Delta comprises about 150,000 acres constrained by levees. River ,flows
<br />to the Delta have been reduced nearly 75 percent, resulting in less silt, fewer nutrients, and higher salinity
<br />and concentrations of pollutants. Species diversity has diminished dramatically, and nonnative and
<br />invasive species dominate the landscape. Several native species in Mexico are listed under both Mexican
<br />and U.S. law as endangered. One important area in the Delta is the Cienega de Santa Clara, over 10,000
<br />acres of thickly vegetated marsh created by saline agricultural return flows from the United States which
<br />are not accounted as a part of the required delivery from the United States to Mexico under the Mexican
<br />Treaty.
<br />
<br />In the United States, River fish and birds are listed as endangered under the Endangered Species Act. The
<br />Salton Sea, created by the flooding of an irrigation canal in the early 20th century, has become an
<br />important stopover in the Pacific Flyway, replacing some of the ecological function of the Delta. But the
<br />Sea has also become an environmental liability, resulting in a massive federally funded initiative to study
<br />the Sea and its restoration.
<br />
<br />State Law in the United States
<br />The beds and banks of navigable waters are owned by the states. For the most part, the Colorado River
<br />states base their water allocation systems on the prior appropriation doctrine, although California follows '
<br />a mixed riparian-appropriation system. Water rights are permitted or adjudicated based on priority of
<br />appropriation. With some exceptions, water rights require diversion and beneficial consumptive use.
<br />Transferability of water rights to new uses, points of diversion or places of use are generally allowed.
<br />
<br />Federal Law in the United States.
<br />, Water use in the Colorado River states is, of course, subject to the same set of general federal laws,
<br />': particularly federal environmental laws, as in the Great Lakes States noted in the discussion above.
<br />'Additionally, some particular federal laws and Congressionally approved interstate compacts allocate the
<br />"peneficial consumptive use of water among the states and establish rules for the operation of federal
<br />"reservoirs on the River in furtherance of that apportionment.
<br />
<br />':The Colorado River Compact perpetually apportioned beneficial consumptive use of the River's water to
<br />,!he Upper and Lower Basins, and imposed on the Upper Basin States the obligation to not deplete the
<br />:tlow of the River below 75 million acre feet in any ten year period, measured at Lee's Ferry, Arizona.
<br />;;~Ithough the Compact acknowledged the potential of a treaty allocating water between the U.S. and
<br />" ,exico, it reserved such exercise of federal authority to the future. In the Boulder Canyon Project Act of
<br />(;}928. as upheld in the Supreme Court Decree in Arizona v. California, Congress apportioned the
<br />consumptive use of water among the Lower Division States, and authorized the Secretary of the Interior
<br />':t&enforce the apportionment through water delivery contracts from Lake Mead. In 1948, the Upper
<br />;/~Ivision States apportioned consumptive use among them by cornpact. The Secretary of the Interior does
<br />,;,;l,19t have the same type of authority in the Upper Basin as he does in the Lower Basin. In the Upper
<br />~\;I~llsin, water rights are developed., allocated and administered under state law.
<br />
<br />i,\~~rsuant to federal law, the Secretary of the Interior promulgated operating criteria for the storage of
<br />})yater in and release of water from system reservoirs. Each year, the Secretary adopts an annual operating
<br />>:~lari, including declarations of shortage, normal or surplus conditions on the River. In 1992, in the Grand
<br />:;;;;Ganyon Protection Act, Congress directed the Secretary to modify power operations at Glen Canyon Dam
<br />L~()as to minimize negative effects on downstream resources in the Grand Canyon. These operations are
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