Colorado River

Pulse Flow Results

In Spring 2014, the historic pulse flow took place, bringing water back to the Colorado River Delta. The pulse flow is part of Minute 319, an agreement between the United States and Mexico, which runs through 2017.

Recently, the International Boundary Water Commission, United States and Mexico sections, released an interim report outlining the scientific results to date of this incredible event.

Here are some of the highlights:

  • The pulse flow inundated approximately 1,600 ha (4,000 acres) of the floodplain, including the managed restoration sites that were primary targets of the flow design and connected the river from Morelos Dam to the Gulf of California for the first time since 1998.
  • Native riparian trees have returned in many places, most successfully in actively managed restoration sites, where managers graded and connected abandoned meanders to the main river channel; mechanically cleared nonnative vegetation; and provided supplemental, post-pulse-flow water. This preparation and subsequent maintenance and monitoring of managed restoration sites definitively demonstrated that ecological restoration is possible, even with extremely small water volumes compared to historical flows.
  • The pulse flow caused a 16% increase in remotely-sensed vegetation greenness along the channel and floodplain compared to pre-pulse-flow conditions. This result occurred even in areas that the surface water did not inundate, where existing vegetation is supported by groundwater.
  • The abundance and diversity of birds in the floodplain of the Colorado River in Mexico increased after the 2014 pulse flow, with the highest concentrations in the restoration sites. The response was maintained in 2015. Migratory waterbirds, nesting waterbirds, and nesting riparian birds all increased in abundance. All told, 19 species of conservation interest increased 49% from 2013 to 2015, including Gila Woodpecker, Brown-headed Cowbird, Ash-throated Flycatcher, Yellow-breasted Chat and Song Sparrow.

A multinational, multidisciplinary, multi-organizational science team collaborated for three years to design the pulse flow and monitor its hydrologic and ecological responses, as documented in this report. The team includes scientists from academia, government agencies, and non-governmental conservation organizations, who continue to monitor outcomes through 2017.

Scroll down to see a series of before and in-progress photos.


Point 22-a

CO Pulse22 032114 2 640x400

March 21, 2014

CO Pulse22 041014 640x400

April 10, 2014

CO Pulse 9

Sept. 29, 2014

CO Pulse Flow 22 640x400

March 28, 2015

CO Pulse 5

Sept. 12, 2016


Point 22-b

CO Pulse 1

March 21, 2014

CO Pulse 3

April 10, 2014

CO Pulse22 092914 2 640x400

Sept. 29, 2014

CO Pulse 4

Sept. 12, 2016


Point 24

CO Pulse 5

March 21, 2014

CO Pulse 6

April 10, 2014

CO Pulse 9

Sept. 29, 2014

CO Pulse 7

Sept. 12, 2016

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