Damage from a spring earthquake in Mexico set the stage for a breakthrough last weekend in tense negotiations between the United States and its southern neighbor that some hope will usher in an era of cross-border trading of water rights in the parched Colorado River Basin.
Mexico has agreed to store some of its share of the river's water over the next three years in Nevada's depleted Lake Mead reservoir while the country repairs 398 miles of canals and pipelines damaged April 4 in the Mexicali region by the 7.2-magnitude earthquake.
Mexico's three-year water deposit -- accounting for less than 1 percent of Mead's total capacity -- will do little by itself to alleviate the critical water shortage in the southwestern United States or reverse the decadelong decline in the reservoir's water levels, analysts said.
Nearly full in 1999, Mead has shriveled to 39 percent capacity. By next September, the reservoir's water is projected to drop to within 18 inches of a level that would trigger the first declaration of a shortage and force cutbacks in water deliveries to Arizona and Nevada. Water managers are expected to head off that declaration by shifting water from Lake Powell (Greenwire, Aug. 12).
Mexico's small water deposit "might postpone that briefly," said Michael Cohen, senior research associate at the Pacific Institute, a nonpartisan think tank focused on water issues. "The current trend line is that demand exceeds supply," he said. "There's just going to be shortage after shortage until we figure out ways to reduce demands on the system, unless somehow the hydrology of the system improves dramatically."
More importantly, experts say, the accord signed by Interior Secretary Ken Salazar and Mexican Environment and Natural Resources Secretary Juan Rafael Elvira Quesada in Mexico City last weekend marks a key major step in bringing Mexico into a system of water-trading being promoted by the cash-rich and water-poor Southern Nevada Water Authority, which supplies water to Las Vegas and draws 90 percent of its supply from Lake Mead.
In addition to helping water utilities, the trading program aims to boost springtime water flows to the Colorado River's desiccated delta to improve riparian habitat and facilitate bird migration and to invest in desalination plants, reservoirs and other technology in Mexico.
Tony Willardson, executive director of the Western States Water Council, whose representatives are appointed by the governors of 18 Western states, hailed the weekend's agreement as a win for both the United States and Mexico.
"From Mexico's standpoint, they could not use the full allocation delivered to them," Willardson said. "There is room in Lake Mead to store that water, and I think then, in the future, the U.S. would be looking for opportunities to work with Mexico in the future to provide more water to the U.S."
Said Cohen: "They were talking about this for years, and then the earthquake hit. ... The fact that they could complete this agreement is a big step forward."
The United States and Mexico now claim rights to far more water than the Colorado River contains.
Seven basin states -- Arizona, California, Colorado, Nevada New Mexico, Utah and Wyoming -- agreed to divide 15 million acre-feet of water in the 1922 Colorado River Compact, before apportioning another 1.5 million acre-feet to Mexico in a 1944 treaty. An acre-foot is 325,851 gallons, or enough water to cover an acre to a depth of a foot.
Altogether, the agreements represent a vast overestimate of the Colorado River's volume. Natural river flows from early this decade averaged about 80 percent of early 20th-century volumes, dropping to as low as 45 percent of that at one point during an ongoing, 11-year drought.
In 2007, the Western states and federal government recognized that and reached a "shortage sharing" agreement on how to split cutbacks when they become necessary.
How much of that shortage Mexico would share was never spelled out. U.S.-Mexico talks are now set to resume next month over a comprehensive agreement that will determine how water shortages are shared. Salazar has deemed striking a deal on that measure a "top priority for 2011."
"We are in the midst of an ongoing, historic drought in the Colorado River Basin," Salazar said. "So now, more than ever, water users and stakeholders up and down the Colorado River have a shared interest in improving the reliability, certainty, and efficiency of water deliveries for all parties."
Under the weekend pact, Mexico will store as much as 260,000 acre-feet of water in Lake Mead through the end of 2013.
The agreement recognizes the need to "minimize the impact of potential shortage conditions in the Colorado River Basin" in light of the "growing recognition of the potential adverse impacts of climate change."
Delivery of the stored water to Mexico after 2013 will proceed, the agreement says, "taking to consideration the desire of both countries to schedule delivery of this water in such a fashion so as not to trigger or exacerbate any potential shortage conditions in the United States."
Environmental groups cheered the pact because of the possibility that water exchanges could be used to simulate a boost of flows to the river delta in Mexico, which would produce vast benefits to the delta-region ecosystem and bird migrations.
Jennifer Pitt, director of the Environmental Defense Fund's Colorado River Project, said the agreement "proves that diplomacy deployed to create additional flexibility on the Colorado River has great potential."
"It can improve water supply reliability for water users in our country and Mexico and protect our invaluable environmental resources," Pitt said.