by Greg Walcher, E&E Legal Senior Policy Fellow
As appearing in the Daily Sentinel

Stephen Sturgeon, a Utah State University historian, wrote a legislative biography of Western Slope congressman Wayne Aspinall, called “The Politics of Western Water.” He laments that Colorado controls less than half of its water, because of legal requirements. “Colorado has lost nearly every court battle it has fought to keep exclusive control of its water supply,” he writes. “As a result, Colorado has been forced to enter into interstate water compacts with all of its neighbors except Oklahoma, plus all the states in the Colorado and Rio Grande river basins.”

Though they already have over half of Colorado’s water, the other states are never satisfied, always wanting to “renegotiate.” Perhaps Colorado loses so many water battles with other states because it has fought on the wrong ground. Consider how those interstate compacts work in the case of the Colorado River. In the 1920s its water was divided between Upper and Lower Basins, half the water allocated to each. The allocations were based on an annual flow of about 15 million acre-feet (MAF), the historical average at the time. The Lower Basin states of California, Nevada, and Arizona were allocated 7.5 MAF of water, as were the Upper Basin states of Colorado, Wyoming, Utah, and New Mexico.

California convinced Congress to distribute the Lower Basin’s half by population: 4.4 MAF for California, 2.8 MAF for Arizona, and 0.3 MAF for Nevada. Arizona only agreed when promised construction of the Central Arizona Project (CAP), to divert its share to Phoenix. Then, California fought construction of the CAP, and spent years in court claiming Arizona had abandoned its share.