State of Arizona, complainant v. State of California, Palo Verde Irrigation District, Imperial Irrigation District, Coachella Valley County Water District, Metropolitan Water District of Southern California, City of Los Angeles, California, City of San Diego, California, and County of San Diego, California, defendants : the United States of America and State of Nevada, interveners : State of Utah and State of New Mexico, impleaded defendants : report / Simon H. Rifkind, special master

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254 IV. The Claims of the United States to Water in the Mainstream of the Colorado River The United States claims, in addition to control of the mainstream by reason of the Boulder Canyon Project Act and its ownership and management of the various dams and works which regulate mainstream water, the use of water in the Lower Basin for a variety of its projects and needs. The United States urges that it has reserved water for the use of the various Indian Reservations, National Forests, Parks, Recreational Areas, Monuments, Memorials and lands under the control of the Bureau of Land Management located in the Lower Basin. The United States also claims the right to fulfill its treaty obligations by delivering 1,500,000 acre-feet of water per annum in the Colorado River at the Mexican border, and by consuming water on wildlife refuges and management areas located in the Lower Basin. Finally, the United States claims the right to deliver water from Lake Mead to Boulder City, Nevada, pursuant to a federal statute. A. Indian Reservations The United States argues that it has reserved water flowing in the Colorado River and its tributaries in the Lower Basin for the needs of all of the Indian Reservations located within the Lower Basin. Thus the United States claims that each Indian Reservation has the right to divert and consume the amount of water necessary to irrigate all irrigable acreage on the Reservation and to satisfy related needs, subject only to the priority of appropriative rights established before a particular Reservation was created and water reserved for its benefit. Arizona argues that the rights of the various Indian Reservations on the tributaries ought not to be adjudi-