Report Documents Initial Results of Environmental Water Release on the #ColoradoRiver — IBWC

The Colorado River Delta in May, 2014. Photo courtesy NASA.
The Colorado River Delta in May, 2014. Photo courtesy NASA.

Here’s the release from the International Boundary Waters Commission (Sally Spener/Gilbert Anaya):

The International Boundary and Waters Commission, United States and Mexico (IBWC) today released the Initial Progress Report for the Minute 319 Colorado River Delta Environmental Flows Monitoring. The report documents initial success in delivering water to key areas in order to promote habitat restoration in the Colorado River riparian corridor.

Minute 319 is a 2012 IBWC agreement on U.S.-Mexico cooperation on a variety of Colorado River issues, including the environment. The Minute provides for a pulse flow — a one-time event to deliver water to the environment in the Colorado River Delta in Mexico. The pulse flow release, totaling approximately 105,392 acre-feet (130 million cubic meters) began March 23, 2014 and ended May 18, 2014. The water was intended to help restore native vegetation and wildlife habitat in parts of the Colorado River and its Delta that usually have little to no water.

A team of scientists, environmental experts, and technical personnel from universities, non- governmental organizations, and federal agencies from the United States and Mexico closely monitored the pulse flow under the Commission’s coordination. Their Initial Progress Report documents the inundation of 4,522 acres (1,830 hectares) of river channel and floodplain, including key habitat restoration sites. The report confirms the river’s temporary reconnection with the sea. Scientists also observed that a significant amount of water infiltrated to groundwater. Another key finding is the pulse flow’s effect in dispersing seeds and germinating both non-native and native vegetation, including cottonwood and willow, two species important to ongoing habitat restoration efforts. Preliminary observations further indicate an increase of migratory bird species along open water areas and at the active restoration sites.

“The report shows we were successful in delivering environmental water to key areas. I look forward to hearing from our team of scientists as they continue to study the pulse flow’s impact on our habitat restoration efforts,” said U.S. Commissioner Edward Drusina of the IBWC.

Mexican Commissioner Roberto F. Salmon Castelo indicated that these preliminary results confirm that nature always reacts positively even to small efforts like this one that was included in Minute 319, and that this will certainly prompt continued consideration of this type of action in subsequent agreements that could be generated with respect to Colorado River cooperation between both countries.

A mid-term report on the pulse flow is expected in 2016 and the final comprehensive report is expected in 2018.

The Environmental Pulse Flow Initial Progress Report is available on the website of the U.S. Section of the IBWC at: A summary of Minute 319 is available at:

Interviews with scientists who worked on the report can be arranged upon request.

Here’s a release from the United States Geological Survery:

A pulse of water released down the lower reaches of the Colorado River last spring resulted in more than a 40 percent increase in green vegetation where the water flowed, as seen by the Landsat 8 satellite. The March 2014 release of water – an experimental flow implemented under a U.S.-Mexico agreement called “Minute 319” – reversed a 13-year decline in the greenness along the delta.

The year 2000 was the last time the Colorado River reached the Sea of Cortez, between Mexico’s mainland and Baja California. Since then, said Pamela Nagler of the U.S. Geological Survey’s Southwest Biological Science Center in Tucson, Arizona, information from ground measurements and satellites, including NASA/USGS’s Landsat missions and the Moderate Resolution Imaging Spectroradiometer, or MODIS, instrument on NASA’s Terra satellite, have shown a decline in the amount of healthy vegetation along the lower reaches of the river.

This spring’s pulse flow brought back some of the green. Nagler and other members of the Minute 319 Science Team used Landsat 8’s sensors to track the response of plants to the pulse of water. Landsat 8 is a joint project of NASA and the U.S. Geological Survey (USGS).

“The vegetation that desperately needed water was finally able to support more green leaves,” Nagler said. “These are existing trees, like saltcedar, willow and cottonwood, and a lot of shrubs and grasses that hadn’t seen much water in a long time.”

When they compared satellite images of pre-flow August 2013 to post-flow August 2014, the researchers calculated a 43 percent increase in green vegetation along the route wetted by the flow, called the inundation zone, and a 23 percent increase in greening of the riparian zone, or the river banks. Scientists presented these and other results this week at the American Geophysical Union’s Fall Meeting in San Francisco.


“Data from Landsat and the MODIS sensor are well-suited to help people make informed policy decisions about ecosystem health, water management, agriculture and much more,” said Jim Irons, Landsat 8 project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “It’s especially gratifying to see these sensors help scientists evaluate several of those components in one project,” he said. Remote sensing data were used in studies showing the impact of other relatively small flows prior to the Minute 319 agreement, and researchers are currently using Landsat 8 and MODIS to continue studying the effects of the 2014 water release.

Irons said that projects like this one demonstrate that researchers need an archive of good Earth observations of the past to refer to, as well as comparable measurements into the future to measure how a policy changes the landscape. “It’s important to have continuity of the data, so that when a policy decision is made to release the water, we have a system in place to evaluate its effects,” he said.

The Minute 319 pulse flow is part of an agreement adopted by the International Boundary and Water Commission, under the framework of a 1944 U.S.- Mexico treaty that governs water allocations on the Colorado River between the two countries. The 2012 agreement prescribed 130 million cubic meters (105,000 acre feet) of water to flow through Morelos Dam, which straddles the border.

Although most of the water soaked into the ground in the 37 miles below the dam, the river’s surface flow reached areas farther downstream that had been targeted for restoration, and groundwater revived vegetation along the entire route to the sea.

“Remote sensing with satellites such as Landsat and sensors such as MODIS allows scientists to conduct a range of studies they wouldn’t otherwise be able to,” said Karl Flessa, the co-chief scientist of the Minute 319 Science Team studying the hydrologic and biologic effects, and a geosciences professor at the University of Arizona in Tucson.

It’s just one of the tools scientists are using, along with on-the-ground monitoring, to detect changes in the river channel, surface water, groundwater, plant growth, and habitat for resident marsh birds and migratory birds.

“In addition to remote sensing, ground-based geophysical methods such as time-lapse gravity maps provide information about the change in groundwater storage, which ultimately supports riparian vegetation,” said Jeff Kennedy, USGS hydrologist and participant in the study.

The Minute 319 pulse flow was the result of significant cooperation between a large group of partner organizations and agencies in the U.S. and Mexico.

With so many interested parties, and water such a precious resource, scientists will continue to monitor the lower Colorado River Delta’s vegetation and hydrological response to the pulse flow, Flessa said. Using greenness data collected both from the ground and from satellites, researchers will investigate the long-term impacts to groundwater, and they’ll continue to study whether new trees and shrubs take root due to the flow. They will also study how the new vegetation affects birds migrating along the Pacific Flyway.

“There’s hope that we could release a pulse of water below Morelos Dam again,” Flessa said.

More Minute 319 coverage here.

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