California’s Colorado River Board said Wednesday that several water agencies and one tribal nation signed the first in a series of agreements that will conserve up to 1.6 million acre-feet of water.

The agreements build on previous commitments by California, Arizona and Nevada to reduce water use by 3 million acre-feet over three years, cutting usage by about 14% across the Southwest. Much of the reductions are occurring in exchange for payments funded through the Inflation Reduction Act.

Scientists have found that roughly half the decline in the river’s flow this century has been caused by rising temperatures, and that for each additional 1.8 degrees of warming, the river’s average flow is likely to decrease about 9%.

Federal officials said those voluntary conservation efforts help put the region on course to focus on discussing new long-term rules for managing the river over the next two decades.