Interior Department

Arizona, California and Nevada have narrowly averted a regional water crisis by agreeing to reduce their use of Colorado River water over the next three years. This deal represents a temporary solution to a long-term crisis. Nonetheless, as a close observer of western water policy, I see it as an important win for the region. Seven western states – Colorado, Wyoming, Utah, New Mexico, Arizona, Nevada and California – and Mexico rely on water from the Colorado River for irrigation for 5.5 million acres and drinking water for 40 million people. Their shares are apportioned under a compact negotiated in 1922. We now know, thanks to tree-ring science, that its framers wildly overestimated how much water the river contained on a reliable basis. And climate change is making things worse. Some recent commentators have argued for revamping the compact. The lawyer in me shudders to think of the utter chaos that would ensue as states, tribes that were left out of the original...