Rising river temps hit anglers

Wildlife officials urge halt in fishing the Roaring Fork as the waters get warmer.

Anglers in the Roaring Fork Valley are being urged to give fish a break on these hot, dry days.

Colorado Parks and Wildlife and multiple partners are urging anglers to carry thermometers with them and quit fishing when the water in rivers and streams hits 67 degrees.

“We’re definitely concerned right now. Temperatures are reaching the high 60s and even 70 on the Colorado (River),” Kendall Bakich, an aquatic biologist with the agency, said Tuesday.

The agency last sought a voluntary fishing closure on the Roaring Fork for high water temperatures and low flows in 2012. Bakich said anglers are urged to go out earlier in the day, when air and water temperatures tend to be lower.

Rick Lofaro, executive director of Basalt-based Roaring Fork Conservancy, said the nonprofit organization is working with agency, Trout Unlimited and the Roaring Fork Fishing Guide Alliance to spread the word about the voluntary closures of waters in the valley.

Usually there is not a concern because there is a “robust snowpack,” he noted. The runoff keeps the rivers and streams high and cold. This summer, streams and rivers in the Roaring Fork Watershed are running below 30 percent of average, according to the conservancy’s June 28 river report.

“These extremely low flow conditions are unlikely to improve throughout the summer,” the report said.

The Roaring Fork River near Aspen was flowing at 70.4 cubic feet per second Friday. The average flow for that date is 361 cfs.

At Glenwood Springs, the Roaring Fork was flowing at 852 cfs compared with an average of 3,730 cfs. CPW recorded a water temperature of 68 degrees at that location June 28.

Water in rivers and streams warms up faster when flows are low. Cold water holds more oxygen, Lofaro said. As temperatures climb, the water retains less oxygen.

Bakich said higher temperatures raise the metabolism of trout and other fish.

“They’re using more energy,” she said.

So they might not survive if people continue fishing when the water temperature climbs. She is urging anglers not to play long on the line and don’t remove trout from the water.

Many hope that the monsoon materializes and eases the drought this summer. For now, the forecast for the Roaring Fork Valley is dry.

Bakich said if water temperatures start hitting 74 degrees, it may “pave the way for mandatory closures.”