#ColoradoRiver: #Minute 323 includes binational environmental flows for the delta #COriver

Colorado River pulse flow (Minute 319) reaches the Sea of Cortez for the first time since 1998 on May 15, 2014 via the Sonoran Institute

From Water Deeply (Alastair Bland):

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.

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.”

[…]

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.

Detailed Colorado River Basin map via the U.S. Bureau of Reclamation.

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