EAGLE — Due to extremely low flows and warm water temperatures, Colorado Parks and Wildlife is asking anglers to voluntarily avoid fishing on the Colorado River between Kremmling and Rifle.

Effective Wednesday, July 7, the agency is placing a full-day voluntary fishing closure on the Colorado River beginning at the Colorado Highway 9 bridge in Kremmling downstream to the Colorado Highway 13 bridge in Rifle. The voluntary closure will remain in effect until further notice, with a possibility of a mandatory closure to all fishing if conditions worsen.

“We know that anglers care deeply about this fishery,” Parks and Wildlife Aquatic Biologist Lori Martin said. “We need their help to conserve this resource.”

The U.S. Geological Survey gauge on the Colorado River at Catamount Bridge north of Eagle, which typically measures 1,500 to 2,000 cubic feet per second, has been measuring 600 to 700 cfs. The gauge on the Colorado River near Dotsero is running at 1,250 cfs, down from a more typical 3,000 to 4,000 cfs.

High temps, low oxygen

Parks and Wildlife’s aquatic biologists on the Western Slope are concerned about critically high water temperatures and possible low dissolved oxygen. Some fish mortality has been observed this summer. In addition to these issues, another factor unique to this year has been multiple mudslides and flash floods resulting from 2020 wildfires, increasing the sediment load in some river sections.

“With the high sediment load, the fish can’t find clear water,” Parks and Wildlife Aquatic Biologist Kendall Bakich said. “They’ve got to sift through those conditions. And at nighttime, the temp isn’t coming down enough, so there’s no recovery for those fish right now. They’ve just got to hang on.”

These conditions aren’t just limited to the Colorado River.

“We’re likely looking at moving into a voluntary fishing closure on the Yampa River from the upstream boundary of the Chuck Lewis State Wildlife Area downstream to the west city limits of the town of Steamboat Springs,” Parks and Wildlife Aquatic Biologist Bill Atkinson said. “Water temps surpassed 75 degrees on (Tuesday, July 6), so if it hits 75 degrees on (Wednesday, July 7), the closure will be implemented.”

Biologists are also closely monitoring the Fraser and upper Colorado Rivers in Grand County, another area where temperatures are edging toward dangerous levels for trout.

Anglers should be aware that most of the major rivers on Colorado’s Western Slope are experiencing adverse conditions heading into the hottest days of summer.

Tips for anglers

Parks and Wildlife is encouraging trout anglers to consider fishing early in the day and in higher altitude lakes and streams, as hot, dry conditions and reduced water levels increase stress to trout populations.

Heat, drought and low water levels are contributing to elevated water temperatures in much of Colorado, depleting oxygen levels and leaving trout vulnerable. Trout are cold-water fish that function best in 50 to 60 degree water. When temperatures exceed 70 degrees, they often stop feeding and become more susceptible to disease. Warm temperatures and low water levels can also lead to algae blooms in rivers and reservoirs, which cause oxygen levels to drop when algae die and decompose.

Anglers are asked to carefully consider the water and weather conditions when they go fishing for trout. If water seems too warm or fish appear lethargic, it would be best to leave the fish undisturbed.

Martin urged anglers to add a hand-held thermometer to their fishing kits so they can test the waters they intend to fish.

“Anglers should monitor water temperatures and stop fishing when water temperatures start to approach 70 degrees,” she said. “If trout have difficulty recovering after being caught and are acting lethargic, it’s a good decision to call it quits for the day.”

This story is from VailDaily.com.