As the #RoaringForkRiver and #ColoradoRiver heat up, managers try to keep fish cool — #Aspen Public Radio #runoff #COriver #aridification

Click the link to read the article on the Aspen Public Radio website (Caroline Llanes). Here’s an excerpt:

At the confluence of the Roaring Fork and the Colorado River in Glenwood Springs, it’s clear that a big, snowy winter has turned into a big spring and summer for local streamflows, too. On June 23, the water was 50 percent higher than it was at the same time last year, flowing twice as fast, according to a sensor monitored by the U.S. Geological Survey. Provisional data shows the water was colder, too, by a few degrees Celsius. That’s all good news for the fish that call these waters home — at least for now.

“My impression is that it’s a good year in a bad pattern,” said Clay Ramey, a fisheries biologist with the White River National Forest, in an interview in the U.S. Forest Service office in Aspen…

…streamflows in the Upper Basin were nearly 20% lower than the last century’s average, the worst 15-year drought on record. Researchers from the Colorado River Research Group in Boulder estimate that between one-sixth and half of that loss was due to warmer temperatures — nearly one degree Celsius hotter than averages in the 20th century. Their study reported that those higher temperatures were tied to human-caused climate change and increased greenhouse gas emissions, and that “future climate change impacts on the Colorado River will be greater than currently assumed.”

Data from the Western Water Assessment through the University of Colorado Boulder shows similar patterns on the Roaring Fork River. Since the year 2000, streamflows have been 13% lower on average than the 20th century — even though the amount of rain or snow falling didn’t change that much. Wildlife managers have seen the impacts firsthand, throughout an interconnected river system. In 2019, Ramey was counting cutthroat trout in West Divide Creek, which flows into the Colorado River near Silt. In a 100-meter stretch of stream, where fish-counters used to find 30 to 40 adult fish, Ramey said they found just one during that count. Another coldwater species, the mountain whitefish, is struggling too. They’re native to other Northwest Colorado rivers and were introduced to the Roaring Fork in the 1940s. And their populations here have plummeted in the past 15 years or so, which researchers attribute to warmer temperatures in the Roaring Fork River, along with increased sediment flushes from monsoon rain events. One of those researchers is Kendall Bakich, an aquatic biologist for Colorado Parks and Wildlife.

Map of the Roaring Fork River drainage basin in western Colorado, USA. Made using USGS data. By Shannon1 – Own work, CC BY-SA 4.0,

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