The United States and Mexico have signed a new agreement to share the water from the Colorado River, marking the most extensive changes yet to the 1944 bilateral treaty covering the waterway, officials said.

Interior Secretary Ken Salazar oversaw the signing Tuesday in San Diego of the agreement, which seeks to establish mechanisms for dealing with the challenges faced by states in the Colorado River basin, especially droughts.

The International Water and Boundary Commission, or IWBC, worked to craft the new agreement in response to a deal hammered out in December 2010, when Salazar visited Mexico and signed an accord opening the way for the two countries to pursue a long-term strategy for managing the Colorado River.

The IWBC is responsible for managing shared water resources and the boundary between the United States and Mexico.

The new five-year agreement allows Mexico to stockpile some of its share of the water from Nevada's Lake Mead, which is on the Colorado River, in exchange for giving up part of its water during droughts, bringing that country into an arrangement similar to that entered into by several U.S. states that agreed to give up part of their shares of water during droughts.

The agreement also opens the way for California, Arizona and Nevada to buy water from Mexico, with the estimated $10 million generated going to infrastructure improvement projects, especially in areas affected by the 2010 earthquakes in Mexicali, the capital of Baja California state.

The Colorado River is an essential source of water for residents of Colorado, New Mexico, Utah and Wyoming. EFE