Salt Lake City, Utah
Released On: June 16, 2005
While flows observed in some reaches of the Green River were high this year, these flows were not out of the norm in comparison to recent history. For example, peak flows of the Green River near Jensen in 1996, 1997 and 1999, measured 22,000, 24,900 and 20,600 cfs, respectively. In the Ouray reach of the Green River, peak flows measured 29,300 and 31,900 cfs in 1995 and 1997, respectively.
As this season's higher peak flows entered portions of the Green River floodplain at levels not seen recently, some property owners along the Green River expressed concern that the U.S. Bureau of Reclamation (Reclamation) may have changed the way it operates Flaming Gorge Dam to support recovery of endangered Colorado River fish. This was not the case. Dam operations in the spring have remained fairly consistent since the dam was constructed in 1962, with annual peak releases typically at or near the maximum capacity of the power plant (about 4,600 cfs). Releases from Flaming Gorge Dam this year were maintained at maximum power plant capacity during the time of peak flow in the Green River, when inflow into the reservoir was about 5,700 cfs.
Earlier this year, Reclamation, a partner with the Upper Colorado River Endangered Fish Recovery Program, worked cooperatively to arrange to provide additional releases from Flaming Gorge Dam, if needed during spring runoff, to support requested Green River target flows near Jensen. Target flows of 14,000, 16,000 and 18,000 cfs were established according to requirements of planned research studies that had been postponed because of years of drought.
"When the arrangement was made, we were uncertain about how much runoff we would have during the critical time that our research studies needed to occur," said Recovery Program Director Robert Muth. "When we saw the actual and forecasted spring flows for the Yampa River increasing, Reclamation only needed to release an additional 1,700 cfs for two days before the peak to meet our 14,000 cfs target and 2,300 cfs for two days after the peak to meet our 16,000 cfs target."
This small change in dam operations did not result in an unusual spring peak or unexpected levels of water entering the floodplain. Since 1962, peak flows at Jensen of 18,000 cfs or greater occurred 24 out of 44 years, or 55% of the time. During the peak flow this year, more than 75% of the volume of flow in the Green River near Jensen was from the Yampa River and not from Flaming Gorge Dam.
"Inflows to Flaming Gorge Reservoir this spring have also been much higher than in previous years," said Rick Clayton, Hydraulic Engineer with Reclamation's Upper Colorado Regional Office. "Since April 1, 2005, the water surface elevation of Flaming Gorge has increased over six feet and could likely fill to an elevation of 6031 feet above sea level (nine feet from full pool elevation) by the end of the summer. This increase will be nearly 15 feet of elevation by the end of the runoff season."
DOI | Recreation.gov | USA.gov
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