Nature has guaranteed healthy runoff levels in the Colorado River upstream of Grand Junction this spring. A team effort by water managers and others aims to keep those levels strong throughout this week.
Entities including Front Range water utilities and the Bureau of Reclamation on Friday began coordinating water releases from upstream reservoirs in a voluntary effort to prolong peak runoff flows in what's called the 15-Mile Reach upstream of the confluence with the Gunnison River. It's a critical stretch of river for four endangered fish — the humpback chub, razorback sucker, bonytail chub and the Colorado pikeminnow.
River flows at Cameo exceeded 20,000 cubic feet per second Saturday. The coordinated reservoir operations are intended to slow the decline of high flows, sustaining those flows for three to five days this week. The first releases from the coordinated program were expected to arrive Monday night; the flows at Cameo earlier Monday were at 18,900 cfs, according to the U.S. Geological Survey.
Strong flows help remove fine sediment from cobble bars that serve as spawning habitat for the fish, according to the U.S. Fish and Wildlife Service. They also help reconnect the river to backwaters where the fish, especially at the larval stage, can find refuge from the stronger river flows, said Don Anderson, a hydrologist with the agency.
The releases are being made possible by this year's ample winter snowpack, which means reservoir operators can release reservoir water without risking the ability to fill the reservoirs.
Anderson said that in some years the releases are coordinated with the goal of raising peak flows to beneficial levels, but this year the peak flows were high enough it was decided that the reservoir water instead could be used to prolong those flows.
According to a Fish and Wildlife Service news release, under the coordinated operations:
■ The Bureau of Reclamation is increasing releases at Ruedi Reservoir and Green Mountain Reservoir, with the Green Mountain releases including inflows bypassed by Dillon Reservoir, operated by Denver Water.
■ Denver Water is likely to increase releases from Williams Fork Reservoir.
■ Homestake Reservoir, operated by Colorado Springs Utilities, may participate in the releases after peak flows on the Eagle River recede.
■ The Windy Gap Reservoir and Pump Station, operated by Northern Colorado Water Conservancy District, will delay pumping water to Granby Reservoir.
The current effort follows reservoir releases by the Bureau of Reclamation earlier this spring on the Gunnison River to boost flows for endangered fish there. In both cases, the efforts are planned in a way intended to keep from resulting in flooding impacts downstream.
Anderson said the coordinated spring operations on the upper Colorado River started in 1997, and by his count have occurred in 11 years since beginning.
They've occurred every year since 2015, with the exception of last year. Snowpack was extremely low last year and there wasn't enough water to generate peak flows high enough to be very beneficial to the fish and reservoir operators needed to store all the water they could.
Other years, peak flows are naturally high enough that coordinated operations would only aggravate flooding issues.
Anderson said he is impressed by the level of cooperation shown by partners in the coordinated reservoir operations effort. This year the effort has involved a lot of phone calls to discuss the runoff status and discuss operation options during what Anderson said someone in the group characterized as a "bashful" runoff season where peak flows ended up being late in arriving.
He said that while the coordinated releases target the 15-Mile Reach, their benefits extend as far as Moab, Utah, improving management of a river floodplain wetlands there that is being used to help in the recovery of razorback suckers.
Entities including the Colorado River Water Conservation District, Grand Valley Water User Association, Orchard Mesa Irrigation District, Palisade Irrigation District, National Weather Service, Colorado Basin River Forecast Center, Colorado Water Conservation Board, and Xcel Energy also participate in the coordinated reservoir operations effort.