Photo: © Blue Legacy
Reconnecting the Colorado
The Pulse Flow
Progress: In February, 2014, International Boundary and Water Commissioners Edward Drusina and Roberto Fernando Salmon Castelo announced plans to move forward with a one-time release of water down the Colorado River into its channel in the Delta, where water has not flowed regularly since 1960. This “pulse flow” was set in motion by a 2012 U.S.–Mexico agreement on the Colorado River known as Minute 319.
The pulse flow — a temporary release of water designed to mimic the river’s natural spring floods — began on Sunday, March 23, when the gates at Morelos Dam were opened to begin releasing 105,392 acre-feet of water — approximately 0.7% of annual Colorado River flows — downstream into the long depleted Colorado River Delta. The pulse flow is expected to peak at its highest flow rate March 27 through March 30.
The pulse flow will help keep the river corridor healthy by spreading seeds of native vegetation and creating conditions in which those native seedlings can thrive. In addition to restoration benefits, the pulse flow will generate valuable information for both the U.S. and Mexico and be an extremely important step in the process of understanding how best to restore key areas of the once vast Colorado River Delta.
The pulse flow is just one component of Minute 319. In addition to the pulse flow, this policy framework more broadly allows the U.S. and Mexico to share surpluses in times of plenty and reductions in times of drought, provides incentives for leaving water in storage, and conserves water through joint investments in projects from water users in both countries.
How it Works
The pulse flow will take place over approximately eight weeks and consist of four days of flow at a flow rate greater than 3500 cubic feet per second (100 cms), followed by a much longer period of low flows.
Sonoran Institute and Pronatura Noroeste are preparing sites within the river corridor to benefit from the pulse flow by clearing non-native vegetation and opening channels to backwater wetlands.
There is no guarantee that the pulse flow will extend all the way to the Upper Gulf of California. The course and effect of the pulse flow will depend on river conditions at the time the release is made, in addition to a variety of other factors, known and unknown.
The pulse flow is an unprecedented and unique event in the global context. It’s also an extremely important step in the process of understanding how best to restore key areas of the once vast Colorado River Delta. The eyes of the world are on this cooperative effort.
Photos: © Blue Legacy