Below-average snowpack and ongoing drought will hurt flows and fish habitat below McPhee Dam going into spring and summer, according to Colorado Parks and Wildlife.
Water releases from the dam are expected to be less than 15 cubic feet per second and could possibly drop as low as 3 cfs, said Jim White, CPW aquatic biologist, in a news release issued April 14.
During normal snowpack years, McPhee Reservoir fills, and the allocated fish pool allows for a sustained dam release of 60 cfs in summer.
Fish flows increase if snowpack runoff exceeds reservoir capacity, which prompts a recreational boating release. But a recreational water release will not happen this year because of below average snowpack and low reservoir carryover from last water season.
As of April 19, Natural Resource Conservation Service’s Snotels in the Dolores Basin reported 32% of average snowpack for snow water equivalent.
Trout and native fish will be adversely affected by the water shortage below the dam, White said. The 12-mile section of the Dolores River that flows through the Lone Dome State Wildlife Area from below the dam to Bradfield Bridge is a popular tail-water fishery. Most trout fishing is done within the first 6 miles.
White said the lower flows will shrink the river habitat, and many brown and rainbow trout likely will die. The water coming out of the dam is about 42 degrees Fahrenheit, which is an ideal temperature for trout. But with such a low flow the water will warm quickly as it moves downstream.
“This is going to impact the trout fishery,” White said. “I would expect to see about half or more of the trout fishery habitat suffer and lose much of the trout population.”
White suggested that anglers fish early in the day and carry a thermometer to check the water temperature. Fishing should stop when the water hits 70 degrees.
The low flows will also affect native fish that live in the lower reaches of the Dolores River – the flannelmouth sucker, the bluehead sucker and the roundtail chub. The fish, listed by CPW as species of concern, have adapted to warm water, but they still need pools and flowing water to survive.
White is concerned about lower sections of the river drying up or being connected by only tiny rivulets.
“I’m worried that the natives are going to be stuck in isolated pools throughout most of the year at these flows,” White said.
Making the problem worse is the smallmouth bass, an invasive non-native fish that thrives in the lower Dolores River but preys on young native fish. Anglers are encouraged to fish for smallmouth bass; they are abundant, fairly easy to catch, tasty and have no bag or possession limit.
As drought continues to grip the West, more and more rivers will face the same scenario – this year and beyond.
“All of this is a result of three things: low snowpack, dry soil that will absorb runoff and no carryover water in the reservoir from last year,” White said.