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Macroinvertebrates study shows overall good quality of area rivers

April E. Clark
Post Independent Contributor
Glenwood Springs, Colorado CO

BASALT, Colorado – The results of a 2011 study of aquatic insects in the Roaring Fork and Crystal river basins show overall healthy conditions in the river and many of its tributaries.

The Roaring Fork Conservancy, a watershed conservation organization, has released results of its 2011 study on macroinvertebrates, or aquatic insects, in the Roaring Fork Valley.

The study was a collaboration between the conservancy and the Colorado Water Quality Control Division, an agency within the Colorado Department of Public Health and Environment.



“Overall, we live in an area with healthy streams and rivers,” said Chad Rudow, water quality coordinator for Roaring Fork Conservancy. “With a few exceptions, with what the study overall shows, we have met the state’s standards for healthy creek conditions.”

Rudow said 17 of the 20 sites sampled in the Roaring Fork and Crystal watersheds showed scores indicating healthy conditions.



Of the 20 sites, only two, Cattle Creek at the Highway 82 culvert and the Roaring Fork at Slaughterhouse Bridge in Aspen, were considered impaired. Farther upstream in Aspen, the Roaring Fork at the Mill Street Bridge fell into a gray area between healthy and impaired.

The study sampled a variety of aquatic insects, such as mayflies, caddisflies and stoneflies, and used the results to evaluate the health of rivers and streams.

The aquatic insects are seen as good indicators of river health because they have limited mobility, high population densities, and spend a relatively long time in their aquatic life stage before hatching out into adults. They are also highly sensitive to disturbance.

“In layman’s terms, these aquatic insects are like the canary in the coal mine of how the rivers are doing,” Rudow said. “They are very intolerant of pollution and are some of the first insects to disappear. They are a good marking point, as they reflect the quality and quantity of the water.”

According to the study, macroinvertebrate populations illustrated the best water conditions at Thompson Creek above the headgate for the Sweet Jessup Canal, and in the Crystal River at and below Redstone.

Rudow said the positive results regarding the Thompson Creek area, where gas drilling is being pursued, may be of interest to those concerned about potential water pollution.

“The study looked at the overall conditions of the water, and the highest score in its biotype was Thompson Creek,” he said. “There is limited human impact in those areas, and there has been a lot of talk about Thompson Creek lately. The study just so happens to show Thompson Creek as a high-quality stream.”

Upper Four Mile Creek south of Glenwood Springs also showed high scores in overall stream health.

“Just in general, a stream will show good results with less human impact and more natural conditions,” Rudow said.

The study was conducted in late September and early October 2011, a key time of year to study macroinvertebrates, according to Rudow. High snowpack the previous winter led to high streamflows well into the summer of 2011 and likely had a positive effect on the study’s collected data.

Rudow said the study will be repeated during the same period this year, and it may show how much the 2012 drought conditions have impacted streams, rivers and aquatic habitat.

“This year we are moving forward with the study and continuing our research,” he said. “Here we are one year later with exact opposite conditions. We’re working hard to conduct another study showing the two very different conditions that just happen to be one year apart.”

Rudow said this year’s work will pay particular attention to low-scoring spots in the 2011 study.

“Although 2011 exhibited strong, healthy results for Roaring Fork Rivers, the story does not end there,” said Rick Lofaro, Roaring Fork Conservancy executive director. “Continued monitoring is needed over extended periods of time to evaluate changes in the ecosystem, such as increasing water demands or changes in land use practices.”

This year, the Roaring Fork Conservancy has enlisted the help of about 50 valley volunteers in its new Hot Spots for Trout citizen temperature monitoring project. Many of the volunteers are fly fishing guides and anglers in the area who are closely tuned in to water levels, which impact water temperature as they rise or fall.

Fishing guide Tony Fotopulos of Roaring Fork Anglers in Glenwood Springs said his outfit also monitors water temperatures, levels and the aquatic insects featured in Roaring Fork Conservancy’s study.

“The cycle of the hatch can change daily,” he said. “We like to know what we have and what we are seeing out there.”

“As the flows drop, the temperatures go up, and that can be quite stressful on the aquatic insects we study,” Rudow said. “A lot of people in this valley are very tuned into the water levels, so it’s pretty easy to get input from them.

“This is just one of the ways we can monitor the drought conditions we’re experiencing this year,” he added.


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