States agree on use of Colorado River

LAS VEGAS – Seven Western states signed a sweeping agreement on Thursday to conserve and share scarce Colorado River water, ending a divisive battle among the thirsty rivals.

More than 30 million people in California, Arizona, Nevada, Wyoming, Utah, Colorado and New Mexico are affected by the historic agreement.

The 20-year plan, which took effect with Interior Secretary Dirk Kempthorne’s signature, resolved several legal disputes among water agencies and formalized rules to cooperate during the ongoing drought gripping the region.

A key element of the drought plan lets the lower-basin states of California, Nevada and Arizona use the vast Lake Mead reservoir behind Hoover Dam to store water they conserve or don’t need for use later.

For the Metropolitan Water District of Southern California, that arrangement could mean storing almost 1.5 million acre-feet of conserved water in the lake, said Timothy F. Brick, the chief of the MWD board. The district is the water wholesaler to 26 cities and water districts serving some 18 million people.

The plan specifies how and when agencies in each state will face reductions during drought, and sets new rules allowing the reservoirs of lakes Powell and Mead “to rise and fall in tandem, thereby better sharing the risk of drought,” Kempthorne said.

Another agreement lets the Las Vegas-based Southern Nevada Water Authority build a reservoir just north of the U.S. border in California to capture excess water that would otherwise flow into Mexico.

In return for funding the project, expected to cost more than $175 million, Las Vegas will be allowed to draw up to 400,000 acre-feet of water to slake the thirst of a fast-growing region that has reached the limit of water it can draw from Lake Mead.