this local governmental body and the special relationship of one class of citizens to that body releases it from the strict demands of the one-person, one-vote principle of the Equal Protection Clause of the Fourteenth Amendment.

I
The public entity at issue here is the Salt River Project Agricultural Improvement and Power District, which stores and delivers untreated water to the owners of land comprising 236,000 acres in central Arizona.[1] The District, formed as a governmental entity in 1937, subsidizes its water operations by selling electricity, and has become the supplier of electric power for hundreds of thousands of people in an area including a large part of metropolitan Phoenix. Nevertheless, the history of the District began in the efforts of Arizona farmers in the 19th century to irrigate thearid lands of the Salt River Valley, and, as the parties have stipulated, the primary purposes of the District have always been the storage, delivery, and conservation of water.
As early as 1867, farmers in the Salt River Valley attempted to irrigate their lands with water from the Salt River. In 1895, concerned with the erratic and unreliable flow of the river, they formed a "Farmers Protective Association," which helped persuade Congress to pass the Reclamation Act of 1902, 32 Stat. 388, 43 U. S. C. § 371 et seq. Under *358 that Act, the United States gave interest-free loans to help landowners build reclamation projects. The Salt River Project, from which the District developed, was created in 1903 as a result of this legislation. In 1906, Congress authorized