Meager anticipated snowmelt runoff is expected to mean another challenging year for maintaining even below-optimal levels of flows in the Colorado River downstream of the Palisade area for the benefit of endangered fish.
Below-average snowpack combined with low soil moisture conditions due to drought is resulting in forecasts for considerably reduced streamflows and water supplies this year in western Colorado. Snowpack levels in sub-basins of the Upper Colorado River Basin in Colorado currently range from 75-95% of normal, which the Colorado Basin River Forecast Center expects to translate into April-July water supplies ranging from 60-85% of normal in various parts of the basin.
The center is forecasting Colorado River flows at Cameo to peak at 8,500 cubic feet per second this year, just half of average.
What’s referred to as the 15-Mile Reach of the river between the Palisade area and the Gunnison River confluence is of particular concern for the Upper Colorado River Endangered Fish Recovery Program, which focuses on four endangered fish. The stretch is primarily used by two of the fish — the razorback sucker and Colorado pikeminnow. But it’s also used by a third, the bonytail. And a fourth, the humpback chub, which favors downstream stretches such as Westwater Canyon, indirectly benefits from efforts to bolster flows in the 15-Mile Reach.
Flows in the stretch are affected by upstream irrigation diversions for the Grand Valley. The U.S. Fish and Wildlife Service seeks to maintain flows of at least 810 cfs in the stretch. Lower flows affect fish habitat, increasing impacts on aquatic insects the fish eat, difficulty of fish passage up and down the river, fish predation by birds, and even sun damage to fish.
Low flows are of particular concern later in the summer after runoff subsides. Last year, the river likely would have run dry in the stretch multiple times if not for supplemental releases from reservoirs to help the fish. That’s according to Fish and Wildlife Service hydrologist Don Anderson, who is instream flow coordinator for the Upper Colorado River endangered fish progra. He spoke with reservoir operators, local irrigation entities and others Wednesday in a meeting recapping last year’s situation and looking ahead to this year.
Even with the supplemental releases, flows in the stretch averaged only about 400 cfs last August, before rising closer to 500 cfs in September and topping 500 cfs in October.
“We did OK with what we had to work with, thanks to people pitching in and helping out,” Anderson said.
The endangered fish program maintains an annual 5,000 acre-foot storage pool in Ruedi Reservoir above Basalt that can be released downstream to boost flows below Palisade.
But numerous other entities also have been involved in flow supplementation efforts, such as the Colorado River District, Colorado Water Conservation Board, Colorado Water Trust, Exxon’s XTO Energy, and the Ute Water Conservancy District, through measures such as donation and leasing of water that can be released from upstream.
Anderson expects that this year, as happened last year and 2018, there won’t be enough water available to maintain the 810-cfs target minimum flows.
“It’s going to be a challenging year but we’ll do the best we can with what we have to work with,” he said.
In five of the last six years — the drought year of 2018 being the exception — operators of several upstream reservoirs were able to coordinate water releases to boost peak runoff flows in the 15-Mile Reach.
Doing that flushes out sediment in gravel beds that serve as spawning habitat for the endangered fish, and also improves habitat for the insects and other macroinvertebrates they feed on.
“I’m not anticipating we’ll be doing that this year,” Anderson said.
That’s based on comments he’s hearing from some reservoir operators that they don’t think they’ll be able to participate due to water supply challenges. It also reflects the fact that there likely will not be a naturally high enough peak runoff to be build on sufficiently to have much beneficial effect.
Another issue the endangered fish program keeps an eye on is what has come to be called the “April hole.”
That’s an issue that can arise when Grand Valley irrigation diversions have begun before spring runoff season starts, jeopardizing flows in the 15-Mile Reach. If necessary to help flows this April, it appears the endangered fish program may be able to make use of surplus water held over from last year from what’s known as a historic users pool of water in Green Mountain Reservoir, which is located in Summit County and managed by the Bureau of Reclamation. That pool exists for the benefit of irrigators, municipal water providers and others, but can be used to bolster flows in the 15-Mile Reach when not needed for other uses.
Anderson noted that progress is being made in the Upper Colorado River endangered fish recovery effort, to the point that the Fish and Wildlife Service has proposed that the razorback sucker and humpback chub be listed as only threatened rather than endangered.
As things stand, the cooperative agreement and congressional authorization for the program to help the four endangered fish expires at the end of 2023 federal fiscal year. Anderson said discussions are taking place on the program’s future, with the goal of reaching a new agreement with partners and defining what the program might look like in the future, what it might cost and how it might be funded.
Anderson said Congress presumably will receive a report on the program and a proposal for its future by September 2022.
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