The Unsung Heroes of the Colorado River Delta Pulse Flow

The Colorado River Delta pulse flow coursing through the arid Sonoran Desert.
The Colorado River Delta pulse flow coursing through the arid Sonoran Desert. (Photograph by Jennifer Pitt, EDF, with support from Lighthawk)

This spring, the gates were opened at Morelos Dam, the furthest downstream in a string of infrastructure along the Colorado River that store and divert water to people and industries throughout the basin.  Sitting approximately 100 river miles upstream of the Sea of Cortez, Morelos Dam has been the southern terminus of the Colorado River for most of the last half century, leaving the last leg of the river’s course unplumbed.

We have used the Colorado River to extinction, and without an allocated share of the river’s water, the delta that sits below Morelos has been left to dry. Straddling the U.S.-Mexico border, neither nation, and certainly no government agency, felt it had the jurisdiction to address the issues of the delta.  Consequently, nearly two million acres of wetlands and riverside forests disappeared.

Then, in November 2012, the U.S. and Mexico signed a binational agreement, known as Minute 319, which committed to deliver environmental flows for the Colorado River Delta, including a one-time demonstration of a “pulse flow” of water intended to simulate, at a small scale, the spring floods that nature had delivered for eons.  A private water trust joined in that commitment to deliver additional “base flows” to ensure that plants and animals would have water available to keep them alive after the pulse flow.

In addition to bringing much needed relief to the delta, Minute 319 also included a host of modern, flexible water management provisions, including sharing surpluses in times of plenty and reductions in drought, new rights for Mexico to store water in U.S. reservoirs, and binational investments in water conservation.

As logical as this course of action might sound, the political leeway and legal framework that allowed for these terms to be negotiated took years – and many players – to orchestrate.

I’m often asked how the conservation community got the powers that be to agree to the pulse flow.  The answer is that, by including benefits for water users in all sectors in nine states (seven in the U.S. and two in Mexico) and two countries, we created an opportunity for cooperation too good to refuse. The benefits to water agencies managing and using water from the Colorado River are significant to the point that they not only allowed the pulse flow to occur, but in many cases became active participants in ensuring its success.

In short, it took many hands to lift the gates at Morelos Dam.

Officials from Mexico and the U.S. gathered on top of Morelos Dam to celebrate the pulse flow on March 27, 2014.
Officials from Mexico and the U.S. gathered on top of Morelos Dam to celebrate the pulse flow on March 27, 2014. (Photograph by Jennifer Pitt, EDF)

In Mexico, this included federal officials from the Foreign Relations Secretariat, Conagua (the national water agency) and SEMARNAT (the natural resources department), as well as officials from the states of Sonora and Baja California, and leaders from the Mexicali irrigation district.

In the United States, it included the Bureau of Reclamation, the Department of the Interior (whose Secretary serves as “watermaster” in the lower Colorado River Basin), and the State Department.  Water leaders from the seven Colorado River Basin states played a significant role as well. Officials from Arizona, California, Colorado, New Mexico, Nevada, Utah, and Wyoming were all engaged in negotiating Minute 319, and all ultimately provided formal approval.

Within those states, major water rights holders were consulted, some even participating by contributing funds that will help to build a binational water conservation project in the Mexicali Valley.  The list is long and includes, but is not limited to:  Denver Water, the Southern Nevada Water Authority, the Central Arizona Water Conservancy District, and the Metropolitan Water District of Southern California.

Each of these agencies played an important role in lifting the gates at Morelos Dam, and they, too, are among the heroes of the pulse flow.

In the face of a hotter and drier future in the American West, we’re going to need all hands on deck to keep water flowing to cities, farms, businesses, and in rivers. If we can maintain the spirit of cooperation and trust most recently illustrated by the pulse flow, we can set an example for how to manage limited resources across various jurisdictions worldwide.


  1. mike miller
    June 14, 2014, 5:54 am

    I think the water should be pumped back to RMNP after it gets to the Delta.

  2. Thomas Kelly
    Yuma, AZ
    May 30, 2014, 9:12 pm

    This is a wonderful idea, & I’m glad it happened. Unfortunately, due to the drought conditions it probably won’t be repeated. Desalinization of sea water might take the pressure off the Colorado & leave water to let the flow continue.

  3. Ken Albertsen
    May 30, 2014, 10:10 am

    I had to grin when reading that. Don’t get me wrong, the initiative and implementation of the plan are GREAT news for environmentalists. The reason I grin is because, here in Asia, where I reside, such widespread cooperation would be essentially impossible. Even the general concept of aiding an eco-system is essentially unheard of in Asia. Environmental concerns are waaaaay down the list of priorities for Asians. And cooperation among government and private entities are even more elusive. Between countries? Fogedabowdit. Just one of 1,000 examples: The S. China Sea disputes. Has any Asian even suggested those rocky little islands might be designated an Int’l Marine Sanctuary? The thought hasn’t even been broached. Ridiculous.