The United States and Mexico have struck a deal that could raise the level of Lake Mead by about 3 feet and open the spigot on future cross-border Colorado River agreements.
Under the accord announced Monday, Mexico will be allowed to store up to 260,000 acre-feet of water in Lake Mead while it repairs canals and pipelines damaged in a 7.2 magnitude quake that struck Mexicali on April 4.
The extra water could raise the surface of Lake Mead by 3 feet or more, enough perhaps to stave off federally mandated shortages on the Colorado River for another year. Under such a declaration, the amount of water that Nevada and Arizona could take from the system would be reduced.
Every inch of water counts right now, Southern Nevada Water Authority chief Pat Mulroy said. "It could make the difference between having a shortage declaration and not having one."
It also could lead to bigger things, including a comprehensive agreement on how Mexico will share in a shortage and how the two countries might exchange water in the future.
Interior Secretary Ken Salazar and his Mexican counterpart, Environment and Natural Resources Secretary Juan Rafael Elvira Quesada, announced the agreement in Mexico City on Monday and directed their representatives to start talks next month on a larger agreement.
Mulroy, who is playing a direct role in the talks, said she hopes agreement can be hammered out by the end of next year.
"We don't want a conflict with Mexico over the shortage issue," she said. "That's not going to be helpful to anyone, so the sooner we get this worked out the better."
As for potential water exchanges, Mulroy said Nevada could help pay for the construction of ocean desalting plants on the Baja coastline in trade for some of Mexico's Colorado River water.
Mexico is allowed to take 1.5 million acre-feet of water annually from the Colorado under a 1944 treaty with the United States.
Nevada gets 300,000 acre-feet from the river annually. One acre-foot of water is enough to supply two average homes in the Las Vegas Valley for one year.
Talks between the two nations sped up after the Easter earthquake, which damaged almost 400 miles of canals used to irrigate 148,000 acres of cropland just south of the California border.
The quake also damaged the canals that deliver Colorado River water to the cities of Mexicali and Tijuana, but those facilities are still in use, said Sally Spener, spokeswoman for the U.S. section of the International Boundary and Water Commission.
The agreement allows Mexico to store its unused Colorado River water in Lake Mead through 2013. Once the earthquake damage is repaired, Mexico could begin withdrawing its banked water from the reservoir in 2014, though not all at once.
Mexico also is barred from taking its water back if additional withdrawals from Lake Mead would "trigger or exacerbate a shortage," Spener said.
"That language being in this agreement was very important to us," Mulroy said of the Colorado River users in the United States. "That gives us comfort."
Contact reporter Henry Brean at firstname.lastname@example.org or 702-383-0350.