Roaring Fork Valley river temperatures fall with recent rains
GLENWOOD SPRINGS — Steady rains this past weekend and in recent weeks have helped to cool water temperatures in the Roaring Fork River watershed, easing the strain on fish to some degree, according to the river observation group Roaring Fork Conservancy.
But, it’s still a little too soon for anglers and other river users to let their guard down during what’s still a stressful time of year for the fish habitat, between warm waters and low, late-summer stream flows, said Sara Johnson, education and outreach coordinator for the Basalt-based organization.
“The drought is not over because we had one good weekend of rainstorms,” Johnson said. “Episodic weather patterns can still cause quick spikes in water temperatures, and a few hot, dry days can make stream flows drop again.”
While daytime river temperatures on the Roaring Fork near Glenwood Springs in mid-July had been hovering around 70 degrees, well above what’s considered a healthy temperature for fish, the recent weather has served to temper things.
Between July 23 and 29, the highest recorded temperature on that stretch of river was 65 degrees, according to a July 30 report issued by the Conservancy.
In mid-July, the Conservancy rounded up more than 50 volunteers as part of its “Hot Spots for Trout” project.
The “citizen scientists,” as they are referred to, collected temperature readings at 24 different locations on the Roaring Fork, Crystal and Fryingpan rivers between Glenwood Springs and Aspen, recording a total of 70 measurements.
“We had a tremendous response, including a handful of people who helped us out last year and a lot of new folks who’d never done it before,” Johnson said. “It’s a way to help us collect data, but what’s most important is it gives people an opportunity to participate and raises awareness at the same time.”
Summer monsoons that hit about the same time the project was launched this year resulted in cooler water temperatures. Readings ranged from a low of 55 degrees on the Roaring Fork near the Aspen Airport Business Center to 68 degrees at Mill Street Bridge in Aspen.
Readings on the Crystal River during that time period were in the low 60s, and on the Fryingpan River above Basalt, the temperature was a consistent 56-58 degrees.
According to aquatic biologists, adult brown trout tend to thrive when the water temperature is between 54-66 degrees, and become stressed when the temperature climbs above that range for extended periods of time.
Colorado Parks and Wildlife has the authority to close sections of rivers in the state to fishing if the maximum temperature exceeds 74 degrees, or if the average daily temperature is 72 degrees during multiple days.
“The weekend reprieve we just had was helpful for the rivers, for sure, but it’s short-term help given the drought we’re still experiencing,” Johnson said. “As the summer goes on, stream flows will also continue to be lower and lower, which will increase temperatures.”
Flows on the Roaring Fork River at Glenwood Springs, while dropping below 600 cubic feet per second at the beginning of last week, spiked to about 1,600 cfs over the weekend. The river was running at about 900 cfs on Wednesday, according to U.S. Geological Service streamflow data.
The lower Crystal River, which often sees extreme low flows in August, was running at just 53 cfs near Carbondale and 130 cfs near Redstone late last week.
On Wednesday, the Crystal below Redstone was at 227 cfs and at Carbondale was 174 cfs, after spiking at more than 800 cfs during the weekend.
“Right now, with the rains we’ve been getting, the flows are looking pretty good,” said Tom Trowbridge, manager at Roaring Fork Anglers in Glenwood Springs. “We recommend that anglers continue to use a thermometer, and to use caution when catching and releasing fish.
“Play them quickly, handle them gently when you reel them in, and let them go back into the water slowly,” Trowbridge said.
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Imagine Glenwood and The City of Glenwood Springs is slated to host a virtual town hall at 5:30 p.m. Thursday, March 11.