New measures could reduce Glen Canyon Dam’s impact on the Grand Canyon — a bit

As long as the dam remains in place, impacts are inevitable.

 

If the San Juan River were a freeway, Glen Canyon Dam would be a 50-car pile-up. It forces the river to back up and spread out for dozens of miles. As the river morphs into Lake Powell, the sand in its current settles out. A rock overhang at Grand Gulch where boaters once lounged is now buried more than 30 feet deep.

Before the dam killed the current, the San Juan carried all of this silt to the Colorado, which spit much of it through the Grand Canyon, replenishing hundreds of sandbars. These expansive blonde beaches, which form in eddies, are river runners’ favorite campsites, and they provide backwater habitat for fish. But today, about 95  percent of the sediment that once washed through the canyon sits at the bottom of Lake Powell, and the sandbars have shrunk: The Colorado erodes them, but doesn’t build them back up.

This is one of the problems the 1992 Grand Canyon Protection Act was supposed to correct. It directed federal officials to figure out how to manage the dam in a way that did less harm and even protected the national park’s assets. In addition to threatened sandbars, three of eight fish species native to the Grand Canyon have disappeared since the dam went up, and two are endangered.

But can altering dam operations really help the river when the dam itself imperils it? Scientists have explored this question since 1992, and their research informs the Bureau of Reclamation’s draft management plan for the dam’s next 20 years, released earlier this year. Conservationists are optimistic that it will yield improvements downstream, but only small ones. “You’re really just trying to make the best of a bad deal,” says Utah State University watershed sciences professor Jack Schmidt.

U.S. Geological Survey

A sandbar gained sediment after a controlled flood was released from Glen Canyon Dam in 2012.
U.S. Geological Survey

This is the second such plan for Glen Canyon Dam. The first, in 1996, allowed managers to unleash experimental floods to flush sediment from downstream tributaries — the 5 percent not stuck behind the dam — through the canyon. They hoped a rush of silty water would rebuild sandbars. But the floods were politically and logistically difficult, since they resulted in lost hydropower, and the Bureau had to complete complicated environmental assessments before each one. Years passed between floods in 1996, 2004 and 2008, limiting their efficacy. While they did boost sandbars, within six months or so, the beaches eroded again.

Then, in 2012, then-Interior Secretary Ken Salazar authorized floods to occur whenever conditions were right until 2020. Floodwater thundered through the canyon in 2012, 2013 and 2014. It’s unclear if frequent floods can make sandbars larger over time, says Paul Grams, a U.S. Geological Survey researcher, but monitoring suggests they can at least stop further decline.

The new plan goes further by making floods a permanent feature of dam management. “That’s a big deal,” says Ted Kennedy, a native fish biologist with the Grand Canyon Research and Monitoring Center. “Those high-flow experiments were really hard to get implemented.” 

The plan will also kick off new experiments to help fish like the endangered humpback chub. These fish evolved in turbid desert rivers that could reach 85 degrees in summer. Today’s Colorado is a different world: The dam releases water from Lake Powell’s cold depths, and near it, the river hovers around 46 degrees year-round. There’s no way to warm these areas without either draining the reservoir, or adding expensive infrastructure that lets the dam release water from warmer layers near the surface. Neither option is currently on the table.

But there might be other ways to help fish, Kennedy says. Chub spawn almost exclusively in the toasty Little Colorado, then move into nearby parts of the mainstem Colorado, where their growth is inhibited by chilly water. The water does warm as the river twists further from the dam, but though it should be good habitat, few chub live in these downstream reaches.

Scientists think that could be because there aren’t enough bugs to eat there. Aquatic insects lay their eggs at river’s edge, and when the water level drops, as it does daily when water releases fluctuate with hydropower demand, the stranded eggs shrivel and die.

The plan proposes to eliminate flow fluctuations on spring and summer weekends, when electricity demand isn’t quite as high, in hopes of keeping eggs wet and boosting insect numbers. More food might help chub populations colonize and prosper in the river’s lower reaches.

Eric Balken of the Glen Canyon Institute is glad that the Bureau is trying to improve the river’s health. “But it’s just a Band-Aid on a gaping wound,” he says. “What we’re not happy with is that they more or less ignored ideas that they considered outside-the-box thinking.” These include requiring Lake Mead to be filled before any water is stored in Lake Powell, which would reduce the water lost to seepage in the system, warm the river, and allow Glen Canyon to emerge from submersion by draining much if not all of Powell.

The plan, instead, represents “the art of the possible,” says David Nimkin, with the National Parks Conservation Association. He thinks it will yield positive, but marginal, gains. “You can do more harm than you can do benefit with the dam,” he says. “Glen Canyon Dam, for the time that it operates, has a profound impact. And that’s a fact.”

Contributing editor Cally Carswell writes from Santa Fe, New Mexico. 

High Country News Classifieds
  • COMMUNICATIONS AND OUTREACH ASSOCIATE
    Communications and Outreach Associate Position Opening: www.westernlaw.org/communications-outreach-associate ************************************************* Location: Western U.S., ideally in one of WELC's existing office locations (Santa Fe or Taos, NM, Helena,...
  • FREELANCE GRAPHIC DESIGNER & PROJECT COORDINATOR (REMOTE)
    High Country News (HCN) is seeking a contract Graphic Designer & Project Coordinator to design promotional, marketing and fund-raising assets and campaigns, and project-manage them...
  • FILM AND DIGITAL MEDIA: ASSISTANT PROFESSOR OF INDIGENOUS MEDIA, CULTURAL SOVEREIGNTY AND DECOLONIZATION (INITIAL REVIEW 12.1.21)
    Film and Digital Media: Assistant Professor of Indigenous Media, Cultural Sovereignty and Decolonization (Initial Review 12.1.21) Position overview Position title: Assistant Professor - tenure-track Salary...
  • REAL ESTATE SPECIALIST
    To learn more about this position and to apply please go to the following URL.
  • ENVIRONMENTAL GEOPHYSICS
    "More Data, Less Digging" Find groundwater and reduce excavation costs!
  • RARE CHIRICAHUA RIPARIAN LAND FOR SALE
    40 acres: 110 miles from Tucson: native trees, grasses: birder's heaven::dark sky/ borders state lease & National forest/5100 ft/13-16 per annum rain
  • CENTRAL PARK CULTURAL RESOURCE SPECIALIST
    Agency: Oregon Parks and Recreation Department Salary Range: $5,203 - $7,996 Position Title: Central Park Cultural Resource Specialist Do you have a background in Archaeology...
  • STAFF ATTORNEY
    Come live and work in one of the most beautiful places in the world! As our Staff Attorney you will play a key role in...
  • ARIZONA GRAZING CLEARINGHOUSE
    Dedicated to preventing the ecological degradation caused by livestock grazing on Arizona's public lands, and exposing the government subsidies that support it.
  • OPERATIONS MANAGER
    Position Summary: Friends of the Inyo (friendsoftheinyo.org) is seeking a new Operations Manager. The Operations Manager position is a full-time permanent position that reports directly...
  • WATER RIGHTS BUREAU CHIEF
    Water Rights Bureau Chief, State of Montana, DNRC, Water Resources Division, Helena, MT Working to support and implement the Department's mission to help ensure that...
  • EXECUTIVE DIRECTOR
    The Amargosa Conservancy (AC), a conservation nonprofit dedicated to standing up for water and biodiversity in the Death Valley region, seeks an executive director to...
  • DEVELOPMENT & OUTREACH ASSOCIATE
    Southeast Alaska Conservation Council is hiring! Who We Are: The Southeast Alaska Conservation Council (SEACC) is a small grassroots nonprofit based out of Juneau, Alaska,...
  • DESERT LANDS ORGANIZER
    Position Summary: Friends of the Inyo seeks a Desert Lands Organizer to assist with existing campaigns that will defend lands in the California desert, with...
  • IDAHO CONSERVATION LEAGUE
    Want to help preserve Idaho's land, water, and air for future generations? Idaho Conservation League currently has 3 open positions. We are looking for a...
  • LUNATEC ODOR-FREE DISHCLOTHS
    are a must try. They stay odor-free, dry fast, are durable and don't require machine washing. Try today.
  • EVENTS AND ANNUAL FUND COORDINATOR
    The Events and Annual Fund Coordinator is responsible for managing and coordinating the Henry's Fork Foundation's fundraising events for growing the membership base, renewing and...
  • EDUCATION DIRECTOR
    Position Description: The Education Director is the primary leader of Colorado Canyons Association's (CCA) education programs for students and adults on the land and rivers...
  • 10 ACRES OF NEW MEXICO HIGH DESERT
    10 Acres of undeveloped high desert land in central NM, about 45 minutes from downtown Albuquerque. Mixed cedar and piñon pine cover. Some dirt roadways...
  • WATERSHED RESTORATION DIRECTOR
    $58k-$70k + benefits to oversee watershed restoration projects that fulfill our strategic goals across urban and rural areas within the bi-national Santa Cruz and San...