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News & Releases
Mountain-Prairie Region

News Release

Targeted Reservoir Operations Begin May 29 to Benefit Endangered Fishes in Upper Colorado River

For Immediate Release

May 29, 2020

A picture of a Razorback sucker fish against a white background. The fish has light yellow fins, and grey scales that gradually become more dense towards the head, which is a greenish color. The belly is yellow. The fish has a hump behind its head
Razorback Sucker at Gavins Point National Fish Hatchery. Photo: Sam Stukel, USFWS.

DENVER – Sufficient water runoff from melting mountain snowpack in Colorado River headwaters this year means that most headwater reservoirs will more than meet their storage needs. As a result, participants in the Coordinated Reservoir Operations (CROS) program will ramp-up water releases into the Colorado River to benefit four rare fishes protected under the federal Endangered Species Act (ESA). The Colorado River, where it traverses Colorado’s Grand Valley, is critical to the survival of these four endangered fishes: bonytail, Colorado pikeminnow, humpback chub and razorback sucker.

For the fifth time in the last six years, coordinated voluntary reservoir operations will occur as the Colorado River nears its natural spring runoff peak. In years with sufficient snowpack, surplus inflow is bypassed simultaneously from multiple reservoirs to boost river flow without impacting reservoir yields or future water uses. These water releases improve river conditions for the four rare Colorado River fishes. For instance, increased Colorado River flows help remove fine sediment from gravel beds in the river channel (“cobble bars”), which serve as reproductive (“spawning”) habitat for native fishes.

Coordinated reservoir operations will begin May 29 and continue through the coming week. Most reservoirs will increase water releases over several days, maintain at a constant rate for three to five days, and then wind down.

Approximate release and flow amounts include:

  • Green Mountain Reservoir (operated by the Bureau of Reclamation) will increase releases from approximately 350 cubic feet per second (cfs) to around 1450 cfs.
  • Williams Fork Reservoir (operated by Denver Water) currently releases around 200 cfs; this will likely increase to approximately 500 cfs over the coming week.
  • Moffatt Tunnel collection system (operated by Denver Water) will bypass approximately 100 cfs of available flow, beginning May 30.
  • Wolford Mountain Reservoir (operated by the Colorado River Water Conservancy District) will increase outflows from 400 to 500 cfs for approximately 3 days, starting May 30.
  • Northern Colorado Water Conservancy District does not anticipate pumping water from Windy Gap Reservoir to Granby Reservoir this month, allowing for Windy Gap Reservoir inflows to continue down the Colorado River.
  • Willow Creek Reservoir (operated the Bureau of Reclamation and Northern Colorado Water Conservancy District) will continue to bypass 75 cfs of reservoir inflow to support CROS and meet downstream senior water rights.

Reservoir releases are expected to reach Cameo – upriver of Grand Junction – on Monday, June 1 and continue through the week. Flows in the Colorado River at Cameo are anticipated to peak around 12,000 – 13,000 cfs from Monday, June 1 through Thursday, June 4, based on current weather forecasts and planned reservoir operations. Last year’s peak flow was greater than 23,000 cfs.

River flows, including planned reservoir releases, are expected to remain well below riverbank capacity. Water is not anticipated to flood land areas or communities near the Colorado River or along associated waterways.

For detailed information about Colorado River basin streamflow forecasts, visit: www.cbrfc.noaa.gov.

The CROS program is a partnership between owners and operators of upper Colorado River water storage systems, including: U.S. Bureau of Reclamation, Denver Water, Colorado River Water Conservation District, and Northern Colorado Water Conservancy District (Northern Water).

The CROS program was established in 1995 as part of the Upper Colorado River Endangered Fish Recovery Program, a public-private partnership supported by the U.S. Fish and Wildlife Service. Many local, state and federal partners contribute to these efforts, including: Colorado Basin River Forecast Center, Colorado Springs Utilities, Colorado Water Conservation Board, Colorado River Water Conservation District, Denver Water, Grand Valley Water Users Association, National Weather Service, Northern Water, Orchard Mesa Irrigation District, Palisade Irrigation District, Grand Valley Irrigation Company, U.S. Bureau of Reclamation, Xcel Energy and others.

Science indicates that these collaborative conservation efforts are working. Recent scientific analyses of the humpback chub and razorback sucker suggest that these fishes could be reclassified from endangered to threatened under the ESA. Reclassification would be a major conservation milestone for local, state, federal, tribal, public and private partners across the Colorado River basin. Continued collaborative efforts, including the CROS program, play an important role in the ongoing recovery of the Colorado River’s native fishes and habitats to benefit current and future generations. Healthy river systems support vibrant local economies and America’s shared natural heritage, in addition to providing recreational fishing opportunities and supporting industry and agriculture.

The mission of the U.S. Fish and Wildlife Service is working with others to conserve, protect, and enhance fish, wildlife, plants, and their habitats for the continuing benefit of the American people. For more information on our work and the people who make it happen in the West, visit our website, or connect with us through any of these social media channels: Facebook, Twitter, Flickr, YouTube, and Instagram.

– FWS –

U.S. Fish and Wildlife Service

Office of External Affairs

Mountain-Prairie Region

134 Union Blvd

Lakewood, CO 80228


303-236-3815 FAX



Don Anderson, U.S. Fish and Wildlife Service
(720) 232-6330

Sara Leonard, State of Colorado
(720) 670-0089

Victor Lee, Bureau of Reclamation
(970) 461-5484

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The mission of the U.S. Fish and Wildlife Service is working with Others to conserve, protect, and enhance fish, wildlife, plants and their habitats for the continuing benefit of the American People.
Last modified: June 02, 2020
All Images Credit to and Courtesy of the U.S. Fish and Wildlife Service Unless Specified Otherwise.
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