Amid drought and water cutbacks in the U.S.-Mexican borderlands, the Colorado River Delta ecosystem is receiving sorely needed infusions of “environmental water” to spur ecosystem restoration.

In the latest such release under a 2017 binational agreement known as Minute 323, water began flowing May 1 into the once-lush but now parched lower reaches of the Colorado River in Mexico. It was the first of 35,000 acre-feet of water the United States has committed to allocate this year for the delta, whose flows have all but vanished due to the rampant growth of U.S. and Mexican water consumption over the past century.

Sally Spener of the U.S. section of the International Boundary and Water Commission (IBWC), the U.S.-Mexican agency overseeing implementation of Minute 323, anticipates an additional 9,545 acre-feet of water will be released into the lower Colorado through October. That amount, to be contributed by Mexican and U.S. nongovernmental organizations and released from local irrigation systems, will bring this year’s expected total of “environmental water” destined for the withered, Mexican end of the riverbed to 44,545 acre feet. (The Mexican government is not expected to make a water contribution this year.)

In Minute 323, the Mexican and U.S. governments and a coalition of nongovernmental organizations from both countries each pledged to provide 70,000 acre-feet of water for environmental purposes, or a total of 210,000 acre-feet, by 2026. According to the IBWC, the nongovernmental groups provided approximately 26,369 acre-feet from 2018 to 2020, mainly to three major restoration sites located along the Mexican river corridor.

Gabriela Caloca, Baja California-based water and wetlands coordinator for the Mexican group Pronatura Noroeste, visited the delta region after May’s water release. Not only was Caloca pleasantly surprised to see “a lot of water where it hadn’t been flowing,” but was delighted to observe people enjoying a renewed river.

Pronatura Noroeste forms part of Raise the River, the coalition of Mexican and U.S. NGOs which has already restored sections of Mexico’s lower Colorado River, conducted educational outreach and raised US$10 million to purchase Mexican water rights for Minute 323’s environmental-water provision. Coalition members also include the National Audubon Society, Restauremos el Colorado, the Sonoran Institute, the Nature Conservancy, and the Redford Center.

The environmental-water provision of Minute 323 grew out of an earlier binational accord, Minute 319, which featured an initial release into the Colorado River Delta corridor in 2014. (See "‘Pulse flow’ invigorates Colorado River delta" —EcoAméricas, June 2014 and "‘Pulse flow’ boosts Colorado River habitat" —EcoAméricas, December 2016.)

Since environmental-water releases began, scientists and researchers have analyzed their impact on the river ecosystem, learning how best to target the releases and maximize their environmental benefits. In an adverse climate scenario, they say, every inch of water counts.

“We’re acutely aware that there is a drought and we want to be as efficient as possible,” says Lynne Bairstow, Raise the River’s communications director. Advocates envision a series of strategically placed restoration sites along the river, Bairstow says.


Spurring restoration
In a 2020 report by the IBWC, the multistakeholder Environmental Work Group of Minute 323 notes that restoration work carried out under Minute 319 and amplified during Minute 323’s implementation in 2018 restored 1,102 acres of delta habitat, including cottonwood and willow groves, mesquite forests, marshland and open water. The restoration groundwork also involved the cultivation of 60,000 native trees for replanting and the dredging of a channel to better connect the river and the Gulf of California, among other projects.

Bairstow and Caloca say the environmental restoration was slowed but not halted by the Covid-19 pandemic, which hit northern Mexico especially hard.

More broadly, Caloca asserts that cross-border collaboration on delta rejuvenation has spurred growing public awareness in Mexico about the Colorado River and has inspired thousands of locals to participate in various restoration projects and site visits. Fueling the interest, she says, is the growing evidence that “restoration is possible in an ecosystem we thought had disappeared.”

Although Minute 323 doesn’t expire until 2026, the IBWC’s Spener says U.S. and Mexican stakeholders maintain a spirit of cooperation and already are looking ahead to a successor accord.