The U.S. Fish and Wildlife Service has begun asking for water releases from high-country reservoirs to boost water flows in the Colorado River upstream of the Gunnison River confluence and aid endangered fish, while being careful not to exhaust available water that may be needed for the species later in the year.
The agency is seeing what U.S. Fish and Wildlife Service hydrologist Don Anderson on Wednesday said are “quickly deteriorating flow conditions” on what’s called the 15-Mile Reach of the river between the Gunnison confluence and where Grand Valley irrigation diversions occur upstream.
Speaking in a conference call with upstream reservoir operators, local irrigation officials and others who work to cooperatively manage Colorado River flow levels, he said flows in the stretch Wednesday were around 450 cubic feet per second. The longterm median flow at Palisade below where Grand Valley diversions occur is 1,780 cfs for July 23, according to U.S. Geological Survey streamflow data.
Anderson told call participants that according to a report from Fish and Wildlife Service colleague Dale Ryden, fish conditions in the 15-mile stretch “are getting pretty grim.”
There, when water is low the fish are more prone to predation, exposure to more sun especially in clearer-water conditions, and even impacts from recreational river use, Anderson said. The latter is on the upswing on that river stretch as people are restless due to the pandemic and looking to get outdoors.
The Fish and Wildlife Service and partners make use of water leases and contracts, coordinated releases from upstream reservoirs and other means to enhance flows in the river stretch.
Anderson has asked for releases totaling 150 cubic feet per second from three upstream reservoirs to boost flow levels in the stretch. While he indicated a desire to further increase flows, he’s balancing that against a desire to not too quickly go through what he referred to as firm sources of water to hit an ideal flow target, in case some of that water is needed later in the year…
Anderson said some endangered fish, such as young Colorado pikeminnow, are reportedly responding to the current conditions by moving to the lower Gunnison River, which currently has more favorable flows and turbid conditions that benefit them…
One bright spot is the moister weather that is arriving in Colorado and could boost river flows. Treste Huse, a hydrologist with the National Weather Service, said during Wednesday’s call that a more active seasonal monsoon pattern is setting up that will bring a steady increase in moisture to the region over the next several days. While the most rain is expected in southwest and south-central Colorado, she said a total of maybe 1.5 to 3 inches of rain is possible in north-central Colorado. She said the 30-day outlook now calls for an equal chance of above- or below-average precipitation…
Another development that will boost the river’s flows is the expected restoration of operations at Xcel Energy’s Shoshone hydroelectric power plant in Glenwood Canyon by the end of this week. That plant has a senior 1,250-cfs water right but was damaged by river ice this spring. Flows just above the plant have fallen below that point but will be boosted once the plant exercises its right to call for more water.
Endangered fish potentially could benefit later this year from what’s called a historic users pool of water in Green Mountain Reservoir in Summit County. While the pool was created for irrigators, municipal and other water users, some years surplus water from that pool can be used to boost fish flows.
he fish also stand to gain this year from the efforts of the nonprofit Colorado Water Trust. Last year it reached a five-year agreement with the Grand Valley Waters Users Association and the Orchard Mesa Irrigation District, which operate the Grand Valley Power Plant hydroelectric facility near Palisade. The deal calls for the Colorado Water Trust to secure water from upstream sources to deliver to the plant at critical times of year, boosting the plant’s operational capacity when water supply is otherwise limited while also putting more water in the 15-mile river stretch.