DENVER – Colorado on Tuesday lifted some fishing restrictions along a portion of the Colorado River, but biologists warn that droughts, high water temperatures and wildfire sediments in the US West have led to historically low waters. flow, which could force future restrictions on oxygen-starved trout. .
on 7th July Colorado Parks and Wildlife banned the rare 120-mile voluntary fishing. Tuesday’s changes allow anglers — a key driver of Colorado’s summer tourist economy — to fish anytime between midnight and afternoon on the river’s 27-mile stretch, when the waters are cooler. Restrictions have also been partially lifted for 50 miles upstream.
Parks and Wildlife aquatic biologist Kendall Bakich said the release of the Apivar Reservoir, recent rains and a small amount of the cold Colorado River headwaters are being driven into the Denver metro area on the eastern side of the Continental Divide.
Bakich said the smoke from wildfires in western states has also deflected solar radiation that warms the river, slightly lowering the temperature.
“It’s crazy, but every little bit helps,” she said. “Early this spring there have been so few flows that the Colorado River looks more like a creek than a river.”
Several factors, almost all linked to climate change, have left the fish in the Colorado River and many of its tributaries in a precarious position. Climate change has made the American West much hotter and drier over the past 30 years. While cold-water trout thrive in temperatures below 65 degrees Fahrenheit, biologists have recorded temperatures as high as 75 degrees.
Bakich said Colorado’s western slope also experienced minimal spring runoff this year from high Rocky Mountain snowpack — runoff that typically swells the river and replenishes high-quality habitat for fish.
“The second phenomenon we’ve never seen is the warming of the Colorado River’s tributaries,” he said.
In recent weeks, sediments have been flushed into waterways by microscopic bursts of rainfall. This is especially the case in Glenwood Canyon, much of which was burned by the 640-square-mile Grizzly Creek fire last year. Bakich said the debris depletes the oxygen level in the water and scorches the trout’s gills.
Affected species include brown and rainbow trout, mountain whitefish and sculpin which are a food source for larger fish.
Over the years, several environmental groups have opposed the diversion of water in the Denver area, arguing that it is damaging to the drought-stricken Colorado River.
The state’s largest water agency, Denver Water, taps some of that water to serve its 1.5 million residents, about a quarter of Colorado’s population. It is also exploring ways to meet demand while conserving water amid drought.
Bakich said authorities have yet to enforce a mandatory fishing shutdown in large part due to a responsible local angling community.
“Our anglers are very smart. They know when conditions are good and not good. The challenge is with people coming from outside the area,” she said.
Earlier this month the voluntary shutdown was moving from the city of Kremling in north-central Colorado to the city of Rifle in the western part of the state. Now, anglers can fish between midnight and noon from the State Bridge on the Upper Colorado River to Red Dirt Creek west of Glenwood Springs.