U.S. and Mexico agree to share in Colorado River conservation and possible shortage

The United States and Mexico have agreed to update and extend a 2012 deal through which Americans invest millions of dollars in Mexican water conservation in exchange for a share of Mexico’s Colorado River water.

The deal spreads the costs of conservation and the pain of future droughts and shortages across the river’s millions of users north and south. The river supplies water to about 40 million Americans from Denver to Los Angeles.

Whenever drought forces the U.S. to impose cuts under a planned drought contingency plan, the International Boundary and Water Commission said Wednesday, Mexico will agree to cut its take of the river “in parity with U.S. savings."

'A path of cooperation rather than conflict'

The commission said officials from the two nations signed the agreement in a ceremony in Santa Fe, New Mexico, on Wednesday. Under the deal, the U.S. government and Southwestern water users will invest up to $31.5 million in water delivery systems and farm efficiency upgrades south of the border.

In exchange, Mexico will parcel out a portion of its river allotment to various U.S. water agencies over nine years and will reduce the risk of shortages for all of the Southwest by storing some of its water in Lake Mead near Las Vegas.

“This agreement puts us on a path of cooperation rather than conflict as we work with Mexico to address the Colorado River Basin’s many challenges,” U.S. Commissioner Edward Drusina said in a statement.

After the deal's signing, he added that it's "not necessarily the complete fix," given the region's long-term drought, but is a "monumental achievement in collaboration."

Water certainty during drought

The deal “provides certainty for water operations in both countries,” Mexican Commissioner Roberto Salmon said, and allows Mexico to better plan its water use.

A 2007 rule adopted by the states allows the federal government to restrict some of Arizona’s water whenever Lake Mead’s elevation drops below 1,075 feet above sea level to start a year.

That reservoir had threatened to drop that low before a healthy snowfall in the Rocky Mountains last winter raised levels, but officials project there’s still about a 1-in-3 chance it could happen by 2019.

The U.S. is entitled to 15 million acre-feet from the Colorado, but in recent years it has had to draw more from the big reservoirs to get that while still delivering the 1.5 million acre-feet due Mexico.

On the lower river, water is divided among Mexico and three U.S. states. Arizona receives 2.8 million acre-feet per year, California 4.4 million acre-feet and Nevada 300,000 acre-feet.

An acre-foot would cover an acre a foot deep, roughly enough to supply two Southwest households for a year.

EDITORIAL:Mexico's Minute 323 water deal should pay off big for Arizona

Mexico may store as much as a sixth of its yearly share of the river in Lake Mead, helping everyone avoid shortage. In years with adequate water, it can retrieve most of that on top of its regular annual share. But if the reservoir drops to 1,025 feet elevation, when the basin would face crisis, Mexico would not retrieve its stored water.

The U.S.-Mexico agreement does not explicitly authorize a “pulse flow” to the ocean like the environmental restoration experiment that Mexico requested and got in 2014. With that, Mexico spilled some of its own water past a borderlands dam to restore vegetation along the normally dewatered delta.

The deal does allow more regular but targeted flows to certain stretches where non-profit groups have planted trees on the delta.

Updating a treaty

The deal, labeled Minute 323 as an addition to a 1944 treaty dividing the river’s flow, updates a 2012 agreement in which Mexico for the first time agreed to leave some of its share in the U.S. in the event of a shortfall that curtails deliveries to Arizona and Nevada.

Mexico needed help restoring and lining canals damaged by an earthquake, and in return, U.S. agencies, including the Central Arizona Project, chipped in millions and received rights to some of Mexico’s water.

This time CAP will pay $3.75 million for Mexican infrastructure improvements over nine years and will receive 27,000 acre-feet for future use by its customers in the Phoenix and Tucson areas, said Chuck Cullom, the agency's river operations chief.

In all, U.S. water providers will get up to 109,100 acre-feet of Mexico's projected water savings for their total investment. That's more than Tucson Water delivers to customers in a year.

Arizona Gov. Doug Ducey said the agreement will protect the states from future water shortages while affirming the relationship on the river between the U.S. and Mexico.

“Minute 323 allows the states and Mexico to form the partnerships necessary to achieve the goal of protecting Lake Mead, while at the same time protecting the state’s Colorado River water users,” Ducey said in a statement.  

Tom Buschatzke, director of the Arizona Department of Water Resources, participated in the signing ceremonies Wednesday. The agreement, he said, "provides substantial benefits to Arizona, particularly regarding opportunities for augmenting existing water supplies.”

About 50,000 acre-feet from Mexico's conservation will remain in the system to prevent shortages, and 70,000 acre-feet will be dedicated for environmental flows.

CAP and other U.S. water agencies also will help fund a study of seawater desalination options on the Gulf of California, known in Mexico as the Sea of Cortez, which eventually could enable Mexico to use the ocean and leave a larger portion of its river share for cooperating U.S. interests.

“This is an important new step in the collaboration between Arizona, the United States and Mexico to protect Lake Mead and to continue our cooperative relationship,” Cullom said, “and hopefully continue to avoid shortages on the Colorado River.”

'A long, fruitful partnership'

California’s largest urban user of Colorado River water also is contributing.

“We’re laying the groundwork for a long, good partnership, and that’s promising,” said Jeffrey Kightlinger, general manager of the Metropolitan Water District of Southern California.

The Metropolitan Water District supplies water to 26 member cities and districts, which in turn provide water to 19 million people across Southern California.

Kightlinger said the U.S.-Mexico agreement shows “there can be a long, fruitful partnership.”

The 2014 pulse flow was a successful experiment, he said, and the next step is to create permanent habitat areas and “make sure we have water for them.”

Restoring cottonwoods and willows to a dry delta that has grown over with non-native salt cedars is important to a host of migratory birds that live across both countries.

Those efforts including backing from U.S. foundations, which pledged continued support.

“We stand ready to be partners,” said Ted Kowalski, head of the Walton Family Foundation Colorado River initiative. “We would be interested in augmenting that restoration work, which will take water and funding.”

The Walton, S.D Bechtel, William and Flora Hewlett, Gordon and Betty Moore, International Community, and Water foundations sent a joint letter to the international commissioners Wednesday pledging to donate millions of dollars and a third of the 210,000 acre-feet of water envisioned for delta restoration work under the deal.

The two nations and several conservation groups will provide the rest.

Desert Sun reporter Ian James contributed to this article.

Environmental coverage on azcentral.com and in The Arizona Republic is supported by a grant from the Nina Mason Pulliam Charitable Trust. Follow the azcentral and Arizona Republic environmental reporting team at OurGrandAZ on Facebook, Twitter and Instagram.