Map of Colorado River pulse moving toward Sea of Cortez

 

Photo credit: Francisco Zamora, Sonoran Institute.

Update May 16: The Colorado River has now reached the delta for the first time since the 1990s. Conservationists will study environmental effects of the pulse for years to come.

Update May 13 from Karl Flessa: "Image taken Monday May 12.  Tidal waters in foreground, Colorado River in background. Connection will likely take place on or slightly before Thursday's high tide."

Update May 1 from Karl Flessa at the University of Arizona: "The river has resumed advancing, likely in response to the removal of an earthen dam downstream of the CILA restoration site and new, scheduled pulse flow deliveries from the Km 27 wasteway.  We don't know how far this mini-pulse will go."

On March 23 at about 8:15 a.m., a 2012 agreement between the U.S. and Mexico that was years in the making finally got real. Morelos Dam at the international border began releasing water in an experiment meant to restore a parched Colorado River Delta. The pulse of water may even allow the river to reach the Gulf of California for the first time since the late 1990s (and even so, reaching the ocean hasn't been a regular occurrence since the 1960s). The agreement, known as Minute 319, amends the 1944 U.S.-Mexico Water Treaty to guide bi-national management of Colorado River water until 2017. Over the course of eight weeks, the current flow, which is mostly through the Morelos dam, will release about 105,000 acre-feet of water (an acre-foot is about 326,000 gallons); the final release is planned for May 18. 

Karl Flessa, co-chief scientist of the Minute 319 Monitoring Program, is coordinating multi-agency efforts to understand hydrologic and biological effects of the pulses. Among other things, they're monitoring how much the water table is rising, how many cottonwood and willow seedlings will spring up near the river as a result, and how many more birds show up next year. As far as whether the experiment will reconnect the river with the Gulf in any definitive way, Flessa isn't very optimistic:

"I wasn’t encouraged when I saw the flow at the last crossing on Saturday (April 13). The river’s mouth is blocked by a low sand bar that causes the river’s flow to pond up before the Gulf. Connecting that ponded-up water with the Gulf may depend as much on the effect of the tide as the level of the water. The upper Gulf has a tidal range of 8 meters or so during new and full moons, so there’s a better chance of connection during those times of the month than at other times. And there’s no one geographic spot that’s easy to get to on the ground, where one can definitively state ‘the river has reached the sea.’ We may need to depend on satellite images and observations from small planes. And finally, to be even more downbeat over what is a really upbeat event, the amount of water that may reach the Gulf will be pretty small, and not likely to have much ecological impact. We’d all love to see it reach the gulf, but it’s not one of the stated objectives (of Minute 319). It will have great symbolic value, that’s for sure.”

This map from the Bureau of Reclamation shows the rate at which the water from the dam has moved down the Colorado, beginning in March. Flessa said Wednesday that the next stretch of river will be fairly difficult to monitor. "It's now in a zone that's really hard to get access to -- no more crossings, lots of shallow water and branching channels." Check back for updates we get on the river's progress. Tay Wiles is the online editor of High Country News. She tweets @taywiles.

High Country News Classifieds
  • CARDIGAN WELSH CORGIS
    10 adorable, healthy puppies for sale. 4 males and 6 females. DM and PRA clear. Excellent pedigree from champion lineage. One Red Brindle male. The...
  • A CHILDREN'S BOOK FOR THE CLIMATE CRISIS!!
    "Goodnight Fossil Fuels!" is a an engaging, beautiful, factual and somewhat silly picture book by a climate scientist and a climate artist, both based in...
  • DIGITAL ADVOCACY & MEMBERSHIP MANAGER
    The Digital Advocacy & Membership Manager will be responsible for creating and delivering compelling, engaging digital content to Guardians members, email activists, and social media...
  • DIGITAL OUTREACH COORDINATOR, ARIZONA
    Job Title: Digital Outreach Coordinator, Arizona Position Location: Phoenix or Tucson, AZ Status: Salaried Job ID Number: 52198 We are looking for you! We are...
  • DESCHUTES LAND TRUST VOLUNTEER PROGRAM MANAGER
    The Deschutes Land Trust is seeking an experienced Volunteer Program Manager to join its dedicated team! Deschutes Land Trust conserves and cares for the lands...
  • ASSOCIATE DIRECTOR OF DEVELOPMENT
    The Nature Conservancy in Wyoming seeks an experienced fundraiser to join our team. We're looking for a great communicator who is passionate about conservation and...
  • INDIAN COUNTRY FELLOWSHIP
    Western Leaders Network is accepting applications for its paid, part-time, 6-month fellowship. Mentorship, training, and engaging tribal leaders in advancing conservation initiatives and climate policy....
  • MULESHOE RANCH PRESERVE MANAGER
    The Muleshoe Ranch Preserve Manager develops, manages, and advances conservation programs, plans and methods for large-scale geographic areas. The Muleshoe Ranch Cooperative Management Area (MRCMA)...
  • ARTEMIS PROGRAM MANAGER
    Founded in 1936, the National Wildlife Federation (NWF or Federation) is America's largest and most trusted grassroots conservation organization with 52 state/territorial affiliates and more...
  • ASSISTANT OR ASSOCIATE PROFESSOR OF ENVIRONMENTAL HUMANITIES
    Assistant or Associate Professor of Environmental Humanities Whitman College The Environmental Humanities Program at Whitman College seeks candidates for a tenure-track position beginning August 2023...
  • ANNUAL FUND MANAGER
    Working closely with the Foundation's leadership, the Annual Fund Manager is responsible for the oversight and management of the Foundation's annual operating fund. This is...
  • DATABASE ADMINISTRATOR
    Looking for someone who loves public land and understands the value and importance of data in reaching shared goals as part of a high-functioning team....
  • EXECUTIVE DIRECTOR
    High Country Conservation Advocates (HCCA) in Crested Butte, CO is seeking an enthusiastic Executive Director who is passionate about the public lands, natural waters and...
  • ASSOCIATE DIRECTOR OF VOLUNTEER PROGRAMS
    Are you passionate about connecting people to the outdoors? The Pacific Crest Trail Association (PCTA) is looking for someone with volunteer management experience to join...
  • EXECUTIVE DIRECTOR
    The conservation non-profit Invasive Species Action Network seeks an executive director. We are focused on preventing the human-caused spread of invasive species by promoting voluntary...
  • NEW BOOK: A FEAST OF ECSTATIC VERSE AND IMAGERY
    Dynamic fine art photographer offers use of images to raise funds. Available for use by conservation groups. Contact at www.anecstaticgathering.com.
  • WANTED: TALENTED WRITER
    Write the introduction to A Feast of Ecstatic Verse and Imagery, a book concerning nature and spirituality. Contact at www.anecstaticgathering.com. Writer who works for conservation/nature...
  • MT STATE DIRECTOR- THE WILDERNESS SOCIETY
    The Montana State Director is a member of The Wilderness Society's (TWS) Conservation program team who plays a leading role in advancing the organization's mission...
  • HIGH COUNTRY NEWS EDITORIAL INTERNS
    High Country News, an award-winning magazine covering the communities and environment of the Western United States, is looking for its next cohort of editorial interns....
  • THE MAGICAL UNIVERSE OF THE ANCIENTS: A DESERT JOURNAL
    Bears Ears, Chaco Canyon, and other adventures in the Four Corners area. 60 photos and lively journals. Purchase hc $35 or pb $25 from bigwoodbooks.com...