More than a dozen Native American communities in the Colorado River Basin have yet to have their legal entitlements to a share of the river’s water quantified, according to a new report from the Colorado River Research Group. With the river’s water already over-appropriated (meaning users, largely non-Indian, have built farms and cities that have come to depend on more water than the river seems able to provide in the long run), this is a challenging problem:

Moving forward with efforts to provide the Colorado River tribes with the water needed to sustain communities and build economies is both a legal and moral imperative. The challenge is to do so in a way that embraces creative, flexible, and efficient uses of water, often in partnership with non-Indian water users. Most of the modern progress has come through negotiated settlements, some of which empower the tribes to lease water to off reservation users.

This is most importantly a problem in the Lower Colorado River Basin states, but the CRRG report nicely quantifies the issue throughout the basin, pulling together data from disparate sources in one place. I argue in my forthcoming book (pre-order now!) that failure to include native communities in basin decision making has been a fundamental problem, both in moral terms as well as in terms of practical water management. We have a large group of people legally and morally entitled to water, to borrow the CRRG’s language, that is not yet using it all. This is a huge problem.