In re The General Adjudication of All Rights To Use Water In the Gila River System and Source

This case arose from the ongoing general stream adjudication of water rights in the Gila River system, one of Arizona's largest and most complex water-rights proceedings, involving thousands of claimants including the state, agricultural irrigation districts, mining companies, cities, and several Indian tribes with reservations along the river and its tributaries, including the Gila River Indian Community and the San Carlos Apache Tribe. At issue was how to quantify the federal reserved water rights the tribes hold in their reservations under the Winters doctrine, which recognizes that when the federal government sets aside land as an Indian reservation, it implicitly reserves enough water to fulfill the reservation's purposes. The trial court needed a legal standard for measuring how much water is impliedly reserved for Indian reservations, and the parties disputed whether the "primary-secondary purpose" test used for non-Indian federal reservations, or some other standard, should apply.