On November 27, 2017, the Supreme Court denied review of the Ninth Circuit’s decision in Agua Caliente Band of Cahuilla Indians v. Coachella Valley Water Dist., 849 F.3d 1262 (9th Cir. 2017). In that case, an Indian tribe brought an action against a California water district and desert water agency seeking a declaration that it has a federally reserved right and an aboriginal right to the groundwater underlying its reservation in California’s Coachella Valley. Id. at 1267. The Ninth Circuit found in favor of the Tribe. By denying review, the Court lets stand the Ninth Circuit’s legal conclusion that, under the reserved water rights doctrine, groundwater (in addition to surface water) can be reserved to Indian tribes. As was explained by the Ninth Circuit:
[W]hile we are unable to find controlling federal appellate authority explicitly holding that the Winters doctrine applies to groundwater, we now expressly hold that it does.
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[M]any locations throughout the western United States rely on groundwater as their only viable water source. See, e.g., In re Gen. Adjudication of All Rights to Use Water in Gila River Sys. & Source, 195 Ariz. 411, 989 P.2d 739, 746 (1999) (en banc) (“The reservations considered in [Winters and Arizona] depended for their water on perennial streams. But some reservations lack perennial streams and depend for present and future survival substantially or entirely upon pumping of underground water. We find it no more thinkable in the latter circumstance than in the former that the United States reserved land for habitation without reserving the water necessary to sustain life.”). More importantly, such reliance exists here, as surface water in the Coachella Valley is minimal or entirely lacking for most of the year. Thus, survival is conditioned on access to water—and a reservation without an adequate source of surface water must be able to access groundwater.
The Winters doctrine was developed in part to provide sustainable land for Indian tribes whose reservations were established in the arid parts of the country. And in many cases, those reservations lacked access to, or were unable to effectively capture, a regular supply of surface water. Given these realities, we can discern no reason to cabin the Winters doctrine to appurtenant surface water. As such, we hold that the Winters doctrine encompasses both surface water and groundwater appurtenant to reserved land. The creation of the Agua Caliente Reservation therefore carried with it an implied right to use water from the Coachella Valley aquifer.
Id. at 1270-72. The Supreme Court’s decision not to review the Ninth Circuit’s decision will mean that the case will return to a lower court, where there are remaining fact issues to be adjudicated. Importantly, despite the Ninth Circuit’s holding that groundwater rights can be reserved, the courts have yet to determine the quantity of any such reserved rights. Id. at 1267.
Nevertheless, the Ninth Circuit decision—which the Supreme Court has now let stand—represents a significant development in the law of federal water rights in the west, and will have significant implications for future cases regarding reserved rights.