A new agreement signed between the U.S. and Mexico continues an important collaboration in managing the Colorado River, but also gives new hope for reviving stretches of the river that have run dry.
by Alastair Bland
A NEWLY SIGNED pact between Mexico and the United States is believed to be the first time that two nations have agreed to allocate part of a shared water resource to the environment.
Farmers and cities in both countries will reap benefits from Minute 323, an update to an existing agreement that seeks to sustainably manage the water of the overburdened Colorado River basin.
The new agreement, signed on September 27 in Santa Fe, New Mexico, by officials from both nations, requires the United States to invest millions of dollars in water conservation projects in Mexico – like plugging leaks in irrigation canals and helping farmers implement water-efficient technology.
Minute 323 also allows Mexico, which has no significant reservoirs in the Colorado basin, to store some of its water north of the border. In return, the U.S. will receive a portion of the Colorado River water to which Mexico has historically been entitled.
But the river’s beleaguered delta, which has received barely a trickle of water for years, may see the most dramatic benefits of all. Through 2026 – the lifespan of the new arrangement – 210,000 acre-feet of water, provided by stakeholders both north and south of the border, will be allowed to flow through the lower reaches of the Colorado, just upstream from the Sea of Cortez.
“We don’t know of any other international agreement that provides for binational environmental flows,” said Anne Castle, a senior fellow with the University of Colorado’s Getches-Wilkinson Center for Natural Resources, Energy and the Environment. “Minute 323 is really an agreement between two countries to manage their shared river as one.”
For decades, the Colorado River has not reached the sea. The river essentially dies at the Morelos Diversion Dam, which sends the last of the Colorado’s water into the alfalfa and vegetable fields of the Mexicali Valley, one of Mexico’s most productive farming regions. In 2012, Minute 319 – 323’s predecessor agreement that expires at the end of this year – required that 105,000 acre-feet of water be allowed to pass the Morelos dam and reach the ocean. That only happened during a remarkable but brief two-month period in 2014.
This “pulse flow,” as it was called, helped revive the ecosystem.
“When the river came back, even though it was just for a short period of time, the people came out in droves,” recalled Castle, who was working as assistant secretary for water and science at U.S. Department of the Interior at the time and visited the Mexican town of San Luis Rio Colorado to see the revival of the river.
Castle says the town – once a river settlement but now a place left isolated in the desert by upstream water development – surged to life with the renewed flows. “It was a community celebration,” she said. “There were vendors and bands and carnival rides. It was the most amazing thing to see the human connection to the river.”
Jennifer Pitt, the National Audubon Society’s Colorado River project director, also visited the delta town to see the water that had not flowed for decades.
“Kids came out to see a river they’d never seen before, and grandparents came out to see the river they remembered from their younger days,” she said.
Minute 323 requires the U.S. and Mexican governments and a coalition of environmental groups to bear equal shares of the cost of delivering the environmental flows, which will provide basic seasonal benefits, like supporting the regrowth of riparian habitat stressed by dry years and replenishing local groundwater reserves. Pitt says the delta flows will likely be delivered sporadically through each year’s March-October growing season.
Castle, who was involved in steering the outcome of Minute 319 and calls herself “an interested observer” in the newer agreement, said Minute 323 was a “win-win for both countries.”
In signing the 23-page document, stakeholders north of the border agreed to invest $31 million in Mexican water conservation and development projects, like making farms more efficient, compensating growers who fallow their fields, reducing seepage from irrigation canals and possibly desalinating water from the Sea of Cortez for municipal use.
The water saved or produced through these projects will be stored in Lake Mead, the nation’s largest reservoir, and could produce up to 220,000 acre-feet to be used by the U.S. – including 110,000 acre-feet for the Metropolitan Water District and the 70,000 acre-feet that the country must set aside for environmental uses. The rest of the water produced by the conservation projects will be reserved for Mexico, which already receives 1.5 million acre-feet each year from the Colorado. North-of-the-border users consume about 15 million acre-feet annually.
Lake Mead has not been entirely full since 1999. The lower basin, Castle says, has remained for decades in a state of chronic overuse – a troubling imbalance in which total consumption of the reservoir’s water exceeds the volume of water flowing into it. Since 2000, the lake’s elevation has been steadily declining, though it is currently on the rise thanks to last winter’s heavy precipitation and snowfall. Today the lake is only about 40 percent full – its lowest level since the 1950s.
Minute 323 aims to stabilize the declining level of the lake. When filled, the lake surface elevation is 1,232ft above sea level. It is now at about 1,080ft. The lowest intake on the face of Hoover Dam sits at 860ft above sea level. Below this point, the lake’s water is considered to be “dead storage” – water that is essentially inaccessible.
The agreement’s provision for Mexico to store some of its water in Lake Mead has huge implications, and benefits, for all parties. For one thing, it provides Mexico with a place to keep its water.
“Mexico has no storage reservoirs in the Colorado basin,” Castle points out.
This means the water Mexico has received from the Colorado River flows to its recipients whether they immediately need it or not, rather like a running hose that cannot be turned off.
By impounding some of Mexico’s water behind Hoover Dam, reservoir managers will be better able to keep Lake Mead’s surface elevation above critical trigger points, below which emergency rationing is enforced.
Pitt notes that habitat restoration projects and efforts to support imperiled species will almost always come next in line after the needs of people. By tackling so many of the water supply issues that affect the human users of the Colorado River, Minute 323 makes it possible for resource managers to focus some attention on the basin’s environmental concerns, she says.
“Minute 323 increases the water supply reliability for all users, and that’s so important,” said Pitt. “There’s no way the conservation community can make gains or protect resources if communities’ water supplies aren’t secure.