Click here to read the paper. Here’s an excerpt:

In an earlier Colorado River Research Group publication (Tribes and Water in the Colorado River Basin, June 2016), we noted how more than 2 dozen federally‐recognized tribes in the basin hold rights to divert nearly a fifth of the river’s average flow, with several additional claims unquantified or pending. This assessment was drawn from the 2012 Basin Study which, admittedly, was a preliminary and incomplete review of tribal rights failing to consider tribal plans for additional development and how that development would affect existing uses. These reserved water rights came into existence when reservations were established, many in the late 1800s, so that Indians would be able to establish a viable homeland. Indian reserved water rights are not dependent on use and are not subject to abandonment; most remain undeveloped. The U.S. Supreme Court made clear the importance of tribal water claims in Arizona v. California, quantifying the rights of the five tribes with reservations directly along the Colorado mainstream in these two states to divert nearly one million acre‐feet annually. Since that 1963 decision, many other tribal claims have been resolved—primarily using settlement agreements confirmed by Congress. Other significant claims, however, remain unresolved.

Despite the strength and magnitude of these water rights, tribes with reservations in the Colorado River Basin historically have not been active participants in basin water planning and decision making. However, over the past year, things appear to be changing. For example, while the Basin Study made no attempt to consider tribal plans for additional use of water under their rights or how that development would affect existing uses, it did set the table for a subsequent Tribal Water Study conducted jointly by Reclamation and the Ten Tribes Partnership. That study was issued in December, 2018. Even more recently, Arizona’s participation in the Drought Contingency Plan was made possible in large part due to the participation of the Gila River Indian Tribe and the Colorado River Indian Tribes (CRIT). Each tribe committed 50,000 acre‐feet per year of tribal water for three years to be kept in Lake Mead to help maintain storage levels and reduce the threat of a legal shortage declaration. Arizona will pay each tribe $250 per acre‐foot, or $12.5 million per year, for the water. With these milestones now in place, it is valuable to reexamine what we know of tribal water rights, and what the next steps might be in fully integrating tribes into Colorado River management.