These days there's a bit more water flowing downstream in the Colorado River, the result of an historic agreement between the U.S. and Mexico to engineer an experimental spring flood in an effort to re-establish riparian habitat along the river in both countries and in the Colorado River Delta region of Mexico.
As of Sunday, the United States and Mexico began releasing some 105,000 acre-feet — approximately 0.7 percent of the annual average flow of the Colorado River — to the delta below Morelos Dam on the U.S.–Mexico border near Algodones. The pilot "pulse flow" will peak for several days at a high flow, and then will last for nearly eight weeks, mostly at a reduced flow rate.
This historic event, stemming from the groundbreaking, multi-faceted Colorado River agreement negotiated between the U.S. and Mexico known as Minute 319, will help with efforts by the two countries to re-establish riparian habitat, providing benefits to wildlife species and communities along the river, according to a news release.
The two governments are acting through the U.S. and Mexican sections of the International Boundary and Water Commission.
“The pulse flow is an unprecedented and unique event in the global context,” said Jennifer Pitt, director of the Colorado River Project at Environmental Defense Fund and U.S. co-chair of the environmental work group that helped negotiate the framework agreement for the pulse flow.
“This demonstrated commitment to environmental restoration is a shining example of what two nations can achieve when we work together, and (it) will be very helpful for both governments to obtain information that becomes increasingly relevant as we face droughts with more frequency, not only in the Colorado River Basin but also in other watersheds,” she said.
“The pulse flow is a vital part of our ongoing restoration efforts,” said Francisco Zamora Arroyo, director of the Colorado River Delta Legacy Program at Sonoran Institute. “We know that relatively small amounts of water can make a big difference in the health of the delta region.”
A binational team of scientific experts from U.S. and Mexican federal agencies, environmental groups and universities will be monitoring the event to determine its impacts and gather information on which to base future binational efforts in the Colorado River delta.
Signed in November 2012, Minute 319 provides broader sharing of water throughout the Colorado River Basin when supplies are plentiful and in times of reduced supplies, investments in water conservation and new opportunities to store water in upstream reservoirs such as Lake Mead. The pulse flow is an important element of Minute 319 — a component that both countries agreed to implement in 2014.
Also under Minute 319, the Colorado River Delta Water Trust will deliver another 52,000 acre-feet in “base flows” – a small but steady water supply to sustain new habitat created by the pulse flow.
A coalition of conservation organizations, including EDF, Sonoran Institute, Pronatura Noroeste, The Nature Conservancy, Redford Center and National Fish and Wildlife Foundation, has launched a campaign to raise funds for the trust to purchase rights to this water from willing sellers in the Mexicali Valley, where there is an active water rights market.