The Coachella Valley in California. (Photo: Randy Heinitz/Flickr)

In a legal battle between a Californian tribe and the state's water agencies, experts are seeing a turning point in the history of United States water rights, potentially affecting how water is controlled across the entire country.

In November of last year, the Supreme Court declined to hear a case that the Agua Caliente Band of Cahuilla Indians, concerned about the effects of climate change and the quality of the water in the aquifer, brought against the Coachella Valley Water District and the Desert Water Agency. This Supreme Court decision left standing a Ninth Circuit ruling, which established—for the first time—the principle that tribes have priority over their reservations' groundwater.

The ruling did not, however, establish the volume of water to which the tribe was entitled. Behind the scenes, the Agua Caliente tribe is now debating how to approach the next phases of the lawsuit, which will seek to resolve this fractious question, and could transform how water is used across the parched valley.

"Since the lawsuit was filed, the Coachella Valley has experienced one wet year, but primarily the last five years have been marked by drought," says Steven Moore, the attorney representing the tribe. "In drought years, when the amount of imported water available to come into the valley for recharge declines, there's by definition more reliance on the aquifer. If the new normal is marked by longer, more extreme drought conditions, then I think the tribe would say the Valley is not prepared to properly manage its available water resources."

Origins of the Disagreement

As rising temperatures contribute to increasingly extreme weather events, like floods and droughts, groundwater resources are becoming more and more important to the future of food and water security. It's particularly important to sustain life in the dry Coachella Valley—a place where surface water is practically non-existent for the majority of the year.

But as climate change puts pressure on surface waters, this vital resource is being depleted. Overuse of groundwater resources is already having a visible effect on the Californian landscape: A NASA-funded study published in August found that land in the San Joaquin Valley is sinking by up to half a meter annually as a result of groundwater extraction and drought.

The Agua Caliente Indians raised concerns over reduced groundwater when they first filed the 2013 lawsuit. With the aquifer already in a state of overdraft, as extraction outpaced its replenishment, the tribe worried that the declining availability of imported water would spur further extraction of groundwater from the basin. Meanwhile, they claimed that the water agencies' attempts to recharge the aquifer with water from the Colorado River had lowered the quality of the groundwater.

The tribe decided that it was done with buying water from the water agencies. In fact, the Agua Caliente decided that they probably already owned some of the water in the aquifer themselves, arguing that, when President Ulysses S. Grant set aside land for their permanent use in 1876, he implicitly included the groundwater as part of the bargain.

In 1908, in a case known as Winters v. United States, the Supreme Court weighed in on the issue of who controls water resources in circumstances when non-Indian settlers began to divert water away from the Fort Belknap Indian Reservation in Montana. Even though the 1888 agreement creating this reservation neglected to specify water allocation, the Supreme Court decided that the Tribe had priority over the reservation's water resources, but only of its "navigable and non-navigable streams"—in other words, its surface water. For the last five years, the Agua Caliente tribe has been arguing that these privileges, known as Winters Rights, after the Supreme Court case, apply to groundwater too.

The idea that the tribes might also have priority over their reservations' groundwater was a proposition that seemed alarming to states, which have historically held the power to allocate the water within their own boundaries—a privilege that is "very jealously guarded, especially by the western states," says Michael Campana, a professor and expert in hydrology at Oregon State University. Ten states sided with the water districts, asking the Supreme Court to overturn the ruling.

Nonetheless, in March of 2017, the judges of the U.S. Court of Appeals for the Ninth Circuit sided with the tribe. Eight months later, the Supreme Court declined to review the decision, which subsequently became settled law.

How These Rights Could Spread

Initially a case that pertained to one tribe in California, the decision in Agua Caliente Band of Cahuilla Indians v. Coachella Valley Water District, et al. has ramifications for tribes across the U.S. Many observers were quick to point out that the decision created a framework to resolve disputed claims over groundwater sources, which had previously split states and lower courts as they attempted to adjudicate claims on a case-by-case basis.

Since the decision comes from the Ninth Circuit Court, tribes now have automatic priority over groundwater resources in Alaska, Arizona, California, Hawaii, Idaho, Montana, Nevada, Oregon, and Washington. But the ramifications could spread further than that, as tribes in other states use the victory as the basis for their own legal challenges.

In August, water experts at Stanford University published research in the journal Science that attempted to quantify the effects that the decision would have on the west's water resources. Before the ruling, just 4 percent of all tribal fresh water rights in 17 western states were exclusively for groundwater. By reviewing legal settlements and court decree documents, the Stanford researchers concluded that up to 236 tribes in the Western U.S. have unresolved groundwater claims.

"Against the backdrop of growing legal allocation of surface water and climate change impacts on river flows ... these rights form an important component of sustainably managing this increasingly important resource," says Philip Womble, an attorney and Ph.D. candidate at Stanford who was the lead author of the Science paper. He argues that tribal control could lead to positive effects, like more water being reserved for ecosystems, as well as providing opportunities for economic development on the reservations by leasing access to the water.

In addition, it could help Native Americans to deal with the pressures of climate change, Womble says; stronger rights over the groundwater means that these communities will be less vulnerable to water shortages in the future. "Also, because groundwater storage offers a natural buffer against drought and variable surface water supplies, improved tribal groundwater access may enable adaptation," he says.

Tribes V. Golf Courses

Another advantage of the ruling is that it might force water agencies to rethink how they use precious resources in a time of increasing scarcity, Campana says.

While Coachella Valley is home to the Agua Caliente Indians, it is also home to Palm Springs, a resort town that boasts more than 100 golf courses. Keeping these places green in the desert is a challenge at the best of times. If the court finds that the local Native Americans are entitled to control a significant portion of the groundwater, it could give the tribe major leverage over the management of such spaces.

"This is going to require some re-thinking of water use, possibly on a large scale: the quality of the water, the re-use of the water, and whether or not we can afford to stick golf courses in deserts. In some ways, this may encourage more of a conservation effort." Campana says. "I think this will be interesting in many ways."

Many advocates have welcomed the case as a precedent-setting development when it comes to restoring the rights of Native Americans.

"I think this is the right decision," Campana says. "Native Americans have not always benefited from the law, and [often] got the short end of the stick, and I think they're getting something that they've always been entitled to."

New Landscapes is a regular series investigating how environmental policies are affecting communities across America.