The Feb. 1 front-page article “In West, no deal to save water” highlighted the lack of full agreement among the seven states that rely on the Colorado River. Indeed, California’s absence from the new multistate proposal is telling, highlighting the need for the federal government to be ready to step in and mandate cuts in water use to protect the reservoir system.
But the content of the six-state proposal contains a very important feature: The lion’s share of the proposed reductions in allowable water withdrawals are based on losses from the reservoir system, most notably from evaporation. For the first time, the states have accepted the need to account for evaporation losses from these huge federal reservoirs sitting out in an arid, treeless desert in the Lower Colorado Basin — instead of divvying up all the inflow as though none of the water ever evaporated. Acknowledging the reality of evaporation may not sound like much of a breakthrough, but amazingly, this has not been done so explicitly until now.
There’s still much work left to do to bring the use of Colorado River water down to sustainable levels, but accounting for evaporation losses is one giant first step toward reducing the over-allocation of this critical resource.