By Leslie Sanchez and Eric C. Edwards

Stark power disparities between Native American tribes (tribes) and nontribal entities in California have shaped tribes’ legal standing to assert water rights claims, bargaining power in resolving claims, and the ability to assert meaningful control over water rights. This post outlines the status of tribal water rights in California and explains why they differ from other states. This post is adapted from: Sanchez, Leslie and Eric C. Edwards. 2025. “Bargaining for Tribal Water in California.” ARE Update 28(4): 12-15. University of California Giannini Foundation of Agricultural Economics. Available at: https://giannini.ucop.edu/filer/file/1746023168/21272/ 

In the semi-arid western United States, a system of property rights allocates water among alternative uses. Every western state follows a set of rules that grant priority based on the first year a user diverted surface water for productive use. This doctrine of prior appropriation remains relatively stable because new water rights must queue behind earlier claimants. The priority dates on many senior water rights precede the turn of the 20th century.

The most dramatic change to this ordering over the last 60 years has been the recognition of water rights held by tribes on federal Indian reservations. The Colorado River, the lifeblood of seven states, northern Mexico, and 30 reservations, has seen dramatic changes to its water rights system due to these settlements. Today, tribes own high-priority rights to 22% to 26% of the river’s average annual flows. Their abilities to use these rights in ways that introduce flexibility into the otherwise inflexible appropriative rights system has made them crucial partners in managing basin-wide water shortages.

Relative to other western states, settled tribal water rights claims in California have been substantially smaller and had less impact on the state’s overall water allocation system. The current obstacles to tribal water rights in California are rooted in the state’s relatively early colonization and its aggressive land dispossession tactics, which ultimately diminished tribes’ water claims.

Origins of Tribal Water Rights

When Native American tribes ceded millions of acres of their aboriginal homelands to the United States through reservation treaties with the federal government, they were promised protection to ensure the survival and well-being of their reservations. Most treaties neglected to mention, and did not quantify, the water rights necessary to do this.

In 1908, the U.S. Supreme Court affirmed in Winters v. U.S. that through the creation of reservations, tribes are entitled to water rights sufficient to meet their homeland needs. These Winters rights have a priority date of when the reservation was established and are therefore senior to most appropriative rights.

The Winters decision did not quantify or create water rights for tribes. As a result, surface water resources in western states were fully appropriated for off-reservation use without regard for tribal water needs or prior uses. To obtain legally enforceable water rights, tribes must quantify their rights via an extensive legal process, resulting in either a court decree, or more commonly in the last 40 years, an adjudicated settlement.

To date, 58 of 226 reservations across the 11 westernmost contiguous states have adjudicated rights to 10 million acre-feet (MAF) of water, while 25 with ongoing adjudications have claims totaling nearly 1.4 MAF. One acre-foot is equal to 325,851 gallons, which is enough to support 2–3 households for one year.

Tribal water adjudications in California have followed a different path. The state is home to 109 tribal nations residing on 102 federally recognized reservations. Of these, only 12 have secured rights to 0.2 MAF of water.

Land and Water Rights in California

The United States acquired California from Mexico in 1848 at the start of the Gold Rush and granted it statehood in 1851. The California Land Act of 1851 extinguished tribes’ existing land right claims and entered tribal land into the public domain to be sold to U.S. interests. Also in 1851, the federal government signed 18 reservation treaties that would have entitled 119 California tribes to 7.5 million acres of land across the state. But under pressure from nontribal interests the U.S. Senate neglected to ratify the treaties, despite many of the tribes already having been relocated to the reservations and white settlers already occupying tribes’ ancestral homelands.

The federal government sought to quell ongoing conflicts by creating reservations through executive orders and the ranchería system, where it purchased land for displaced Indians. Both strategies resulted in significantly smaller homelands than in other states, as executive orders were rescinded and altered to diminish tribal land bases.

Diminishing tribes’ land rights effectively reduced future Winters claims and skewed bargaining power in later settlement negotiations in favor of nontribal interests. This is partly due to a 1963 Supreme Court ruling, Arizona v. California, that tied tribal water claims to reservation acreage.

Tribes in California have small land holdings, entitling them to less total water, and their negotiations take 24 years longer to resolve, on average, than negotiations in other western states. Relatively small claims put tribes at a disadvantage during the adjudication process, as large nontribal entities with substantially more resources can absorb the costs of delaying a settlement that would curtail their water use. Only 12% of reservations in California have secured their water rights, compared to 41% in other states.

Despite the limited scope of tribal water settlements to date in California, Winters rights in neighboring states play a significant role in California water allocations. The Klamath Tribes in Oregon, the Pyramid Lake Paiute Tribe in Nevada, and five reservations along the California-Arizona border hold high-priority Winters rights to surface water crossing the California state line.

In Southern California, five tribes hold Winters rights to significant flows from the Colorado River. The Colorado River Indian Reservation (CRIT) has the senior-most rights to 719,846 AF of Colorado River water. The entire state of California holds a separate right to 4.4 MAF.

In 2019, CRIT signed a forbearance agreement with Arizona. Whereby CRIT received $38 million in exchange for banking 150,000 AF in Lake Mead. In return, Arizona staved off mandatory curtailments associated with declining lake levels. In 2023, Congress, with Arizona’s support, passed formal legislation authorizing CRIT to lease water off-reservation in Arizona. These types of market mechanisms can enhance drought adaptation while also providing the tribe with much-needed leasing revenue.

Implications for Groundwater

In 2017, the Ninth Circuit Court of Appeals ruled in Agua Caliente v. Coachella Valley Water District that the Winters doctrine applies to groundwater rights. The ruling comes at a time when the California Sustainable Groundwater Management Act (SGMA) requires groundwater users across the state to draft and implement plans for sustainable groundwater use by 2040. SGMA adjudications provide a clear opportunity for the resolution of tribal groundwater claims under Winters.

Despite uncertainties about how Winters rights will be administered in the context of existing state groundwater law, the history of tribes’ surface water rights in California offers potential lessons. In surface water adjudications, retroactively reallocating rights from powerful off-reservation interests has proven difficult but can ultimately inject elements of flexibility and collaboration into state water governance. As SGMA unfolds, proactive incorporation of tribal claims could include tribal needs in groundwater governance in ways that were not possible for surface water.

About the Authors

Dr. Leslie Sanchez is a postdoctoral scholar in the Department of Agricultural and Resource Economics at UC Davis. Her email is lcsanch@ucdavis.edu and website is www.lesliecsanchez.com/.

Dr. Eric Edwards is an associate professor in the Department of Agricultural and Resource Economics at UC Davis. His email is ecedwar@ucdavis.edu and website is www.ericcedwards.com/.

Further Reading

Sanchez, Leslie, Eric Edwards, Bryan Leonard. 2020. “The Economics of Indigenous Water Claim Settlements in the American West.” Environmental Research Letters 15(9). Available at: https://iopscience.iop.org/article/10.1088/1748-9326/ab94ea

Sanchez, Leslie. 2024. “Bargaining in the Shadow of Prior Appropriation: Concessions and Trade-Offs in Native American Water Settlement Negotiations.” Journal of Political Institutions and Political Economy 5(2): 233–57. Available at: https://nowpublishers.com/article/Details/PIP-0100

Womble Philip, Debra Perrone, Scott Jasechko, Rebecca L. Nelson, Leon F. Szeptycki, Robert T. Anderson, and Steven M. Gorelick. 2018. “Indigenous Communities, Groundwater Opportunities.” Science 361(6401): 453–55. Available at: https://www.science.org/doi/10.1126/science.aat6041