The states of California , Arizona and Nevada have proposed voluntary water-saving measures for the next three years aimed at buying time while negotiations remain deadlocked over the future of shrinking reservoirs filled by the Colorado River. The Colorado River provides water to some 40 million people in the American west. But the two massive reservoirs filled by the river, Lake Mead and Lake Powell, both stand at historically low levels, after consistent overdrawing coupled with reduced snowpack and warming from climate change. The seven states with legal rights to water from the Colorado River have so far failed to agree on how to spread the pain of lost access to the dwindling resource. The lower basin states’ plan would save 3.2m acre-feet of water with the help of voluntary cutbacks through 2028.…