Chasing the Historic “Pulse Flow” Through the Colorado River Delta

Water moves over the sand on the leading edge of the Colorado River Delta pulse flow
Water moves over the sand on the leading edge of the Colorado River Delta pulse flow. (Photograph by J Pitt, EDF)

For one week now, the Colorado River has been flowing into its delta.  It’s the first ever deliberate release of water here to benefit the environment.

That the river is flowing again in its delta is somewhat astounding, all the more remarkable because it’s happening as the result of cooperation between the United States and Mexico under a new collaborative agreement on river and water management.

These releases – lasting eight weeks – are being made from Morelos Dam, about 100 miles (160 kilometers) upstream from the river’s end at the Upper Gulf of California (Sea of Cortez).  About 75 of those river miles (120 kilometers) are typically wet, either from a high groundwater table or the tides that make their way upstream.  But a reach of about 25 miles of the channel have been dry for decades, hot sand baking in the desert sun.

For the Colorado River to flow all the way to the Upper Gulf it needs to cross that sandy reach, and on March 29, 2014 it had made it down about 20 of those 25 miles, and about 40% of the total flow volume had been released.

I spent the afternoon chasing the water, as I have for much of the last week.

To get to the river we drive down farm roads to the levee, where we leave our vehicles and walk across farmland towards the channel.

After years of little or no flow in the dry reach, the old floodplain has been taken over by salt cedar, an invasive shrub with deep roots that can survive in salty soils on little water.

I walked upstream and found the water creeping down.  Water watchers are out every day, tracking the river’s progress as it travels downstream.

While the leading edge can look like a trickle, all you have to do is walk a few feet upstream to find the flow.  We anticipated that a lot of water would infiltrate the sand, but will have to wait for the scientists who are monitoring the flow to tell us how much surface flow is lost along the way.  (It’s not really “lost” though; once it soaks into the sand it becomes part of the groundwater.)

I think it will take another day or two for the river to complete its traverse of the dry bed.  When it hits standing water in the channel (evidence of a high water table), it will move faster, and less of the flow will be lost.  Once there it flows to the sea.

Run river run!


  1. Barry Folsom
    San Jose, CA.
    May 30, 2014, 12:32 am

    To our friends in Oregon. We here in CA. do understand where you are coming. I agree that there are many things that have to be changed here. Understand that is easier said than done but it does need to be. What I haven’t figured out is why this country hasn’t built desalination plants on both coast’s and the gulf. We have the technology and the man power to construct pipelines across this entire country so NOT a single ACRE ever has to be in drought conditions. There was no reason that one of the worlds great rivers, the Mississippi River should have ever gotten so low or the west coast, Southwest or plains should here be in a severe drought. We could easily accomplished.

  2. John Lewis
    Surrey, England
    April 11, 2014, 9:20 am

    I read the article on this project in New Scientist and just had to add a comment here, having now seen the video footage. It’s brilliant to observe just what this collaboration between the US and Mexico has achieved – managed water of the Colorado flowing once again through its historic, but sadly neglected, delta…. a truly excellent outcome! All those involved must be justly proud. Here in the UK we very much hope it’s the robust start of both the long awaited re-greening of the delta and of broader eco-project co-operation between your two countries – well done to you all and keep up the good work!

  3. John Gottes
    Whittier, California
    April 3, 2014, 2:40 pm

    Can you let us know, sort of day by day, how far the water has gotten, how far south the flow has reached?

    Also, could you estimate how much of a flow there is? Perhaps something as simple as Looks about 6″ deep & about 20′ across . . .

  4. Travis
    College Station, Texas
    April 3, 2014, 2:25 pm

    In response to Robert’s comment:
    Water should not be taken from one area of the country to supplement another area’s needs. As Jim and Lauri said, there needs to be better water usage policies in place. The transfer of water (and other resources) disrupts the ecology of the environment where it is taken from and it becomes difficult to get back.

  5. Jim Edgemon
    Boise, Id
    April 3, 2014, 9:46 am

    In response to Robert’s comment, I’m sure the people of Oregon are not interested in creating an Owen’s Valley situation in their part of the world. What is needed is better water usage practices.

  6. Lauri
    April 3, 2014, 7:56 am

    Dude why you asking for Oregon’s water? Why doesn’t Calif start but not watering grass any longer? When i was there we saw fast food restaurants wasting water by watering narrow planting strips in fields of concrete while the water down the drains, stop watering grass and having verdant green lawns in the middle of summer. many many Portlanders let the grass naturally weather during the summer. Also, don’t you know we’ve been affected by the last drought the same as Calif? All but the very Northern portion of Oregon has also been experiencing the drought. What should the rest of the state do for water then? Send it to Calif? As for jobs, short term construction jobs are not job creation, they are just temporary jobs.

  7. Carolyn Hopper
    Bozeman, Montana
    April 2, 2014, 8:50 pm

    Is this flow a one time thing or will there continue to be flow? One can hope that it will continue!

  8. Robert
    Salton Sea CA
    April 2, 2014, 5:24 pm

    We need to build a H2O pipeline from Oregon down here to CA. Provide plenty of jobs and restore the former breadbasket of the world! The technology exists, it could be very similar to the CA Aqueduct!

  9. Andrew Hautzinger
    Albuquerque, NM
    April 2, 2014, 2:31 pm

    What great footage, as the ancient yet still fledgling river finds its path in its ancestral channel. Seeing the burbling early flow is most heartening—congrats to both Mexico and United States partners who worked tirelessly to make this historic event happen—much to be proud of!

  10. Brian
    April 2, 2014, 2:05 pm

    Thanks so much for chasing the water for us, I was excited to see video of it’s progress!

  11. Alan Faz
    Sacramento California
    April 1, 2014, 9:16 pm

    This is really cool. I have been reading all your articles. Please keep us informed. How fair is this form San Luis Rio Colorado? and how many miles left for it to reach the gulf? This is very interesting as I have crossed that empty river in San Luis many times and felt that depressing feeling. Thanks for doing this !!!!