Overlooking Ruedi Reservoir. Photo by David Graf, USFWS

 

Targeted Reservoir Operations Begin June 3 to Benefit Endangered Fishes in the Upper Colorado River

DENVER, Colorado – Mountain snowpack and resulting snowmelt runoff in the Colorado River headwaters this year is sufficient to ensure that most headwater reservoirs will have more than enough inflow to meet their storage needs. As a result, participants in the Coordinated Reservoir Operations (CROS) program are about to ramp-up water releases to the Colorado River in the Grand Junction, Colorado area for the benefit of endangered fish, for the first time since 2020. The Colorado River, where it traverses Colorado’s Grand Valley, is critical to the survival of four endangered species including the Colorado pikeminnow, humpback chub, razorback sucker, and bonytail chub. These voluntary reservoir releases will occur as the Colorado River nears its natural spring runoff peak, improving river conditions for the four endangered fish. In years with sufficient snowpack, surplus water can be passed downstream of reservoirs to benefit endangered fish without impacting reservoir yields or future water uses. This bump in flows helps remove fine sediment from the cobble bars that serve as spawning habitat for the fish, while providing migratory spawning cues and other habitat benefits. These coordinated reservoir operations are planned to begin June 3 and 4 and are anticipated to continue into next week. Most reservoirs will step up releases of bypassed storable inflow over several days, hold those releases at a constant rate for two to ten days, and then wind down. Release and flow amounts are approximate and may be adjusted.

  • Green Mountain Reservoir, operated by the Bureau of Reclamation, will increase releases from approximately 400 cubic feet per second (cfs) to power plant capacity of around 1500 cfs for approximately ten days. Releases from Green Mountain include inflows bypassed by Dillon Reservoir, operated by Denver Water, which will be increased by approximately 400 cfs.
  • Granby Reservoir and Willow Creek Reservoir, operated by the Northern Colorado Water Conservancy District for the Bureau of Reclamation as part of the Colorado-Big Thompson Project, will increase the bypass of storable inflow at Granby Reservoir and bypass all inflows at Willow Creek Reservoir. Granby Reservoir will increase releases from about 240 cfs to approximately 400 cfs for at least ten days. Willow Creek Reservoir will bypass reservoir inflows during the coordinated operation. In addition, Northern Colorado Water Conservancy District’s Municipal Subdistrict will not divert at Windy Gap and bypass all inflows at the Windy Gap Reservoir and Pump Station.
  • Williams Fork Reservoir, operated by Denver Water, is currently releasing around 600 cfs. Releases there will likely increase to approximately 800-950 cfs through June 9. In addition, Moffat Tunnel has ceased diversions through approximately June 10.
  • Ruedi Reservoir, operated by the Bureau of Reclamation, is releasing about 230 cfs and will ramp up to approximately 600-650 cfs by Saturday, and ramp back down starting Monday.
  • Wolford Mountain Reservoir, operated by the Colorado River Water Conservancy District, has a current outflow of approximately 490 cfs, and will increase outflows to approximately 550 cfs on Friday for approximately five to six days.
  • Homestake Reservoir, operated by Colorado Springs Utilities, will not participate in 2024 due to a lack of available excess inflow.

Based on current weather forecasts and planned reservoir operations, flows in the Colorado River at Cameo upriver of Grand Junction are anticipated to peak around 17,500 – 18,500 cfs from Saturday, June 8 through Monday, June 10. These CROS releases are expected to start reaching Cameo on Thursday, June 6 and continue adding to flows through the following week. River flows, including these additional releases, are expected to remain well below defined “bankfull” and flood stages for the area. These additional releases are not anticipated to result in flooding to any communities along the associated waterways.

More detailed information about forecasted streamflows in the Colorado River basin are available from the Colorado Basin River Forecast Center at www.cbrfc.noaa.gov.

The CROS program includes representatives from the U.S. Bureau of Reclamation, Denver Water, the Colorado River Water Conservation District (River District), Northern Colorado Water Conservancy District (Northern Water) and Colorado Springs Utilities as owners and operators of upper Colorado River storage systems. The program was established in 1995 as part of the Upper Colorado River Endangered Fish Recovery Program, which is managed by the U.S. Fish and Wildlife Service. A wide array of partners, including Northern Water, the Colorado River Water Conservation District, Colorado Springs Utilities, Denver Water, the Grand Valley Water User Association, Orchard Mesa Irrigation District, Palisade Irrigation District, the National Weather Service, the Colorado Basin River Forecast Center, the Colorado Water Conservation Board, and Xcel Energy all participate in and contribute to this effort.