Arizona v. California

What happened

Arizona sued California over how much Colorado River water each state could use. Nevada, New Mexico, Utah and the United States later became parties. The United States also claimed water for Indian reservations along the river. The Colorado River Reservation was created by an Act of Congress in 1865 and later enlarged by Executive Order; the opinion says the other reservations were created by Executive Orders dated from 1870 to 1907.

A Special Master took evidence at a lengthy trial and recommended a decree. The Supreme Court held that in the Boulder Canyon Project Act, Congress created its own scheme for dividing the Lower Basin's share of the river among California, Arizona and Nevada. The Secretary of the Interior's contracts, not state water law, control who gets the water.

On the tribal claims, the Court sustained the Master's finding that when the United States created the Chemehuevi, Cocopah, Yuma, Colorado River and Fort Mohave reservations, or added to them, it reserved not only the land but also enough Colorado River water to irrigate the irrigable parts of it. That follows Winters v. United States (1908). The Court said these reservations stay valid even though some were first set apart by Executive Order.

The Court also sustained the Master's conclusions that the water reserved was meant to meet future as well as present needs, and that it covers "all the practicably irrigable acreage on the reservations." The reserved rights took effect when each reservation was created.

Good to know. This covers the Court's 1963 opinion, which was followed by a separate decree.

Summarized with AI assistance from 4 sources and checked against their words; not yet reviewed by historians or by the nations. Report an error