Vail’s Gore Creek shows mixed results in bug populations

Macroinvertebrate populations improving in many places, but areas with human activity are still lagging, and populations have declined in spots

Gore Creek in 2013 landed on a state list of “impaired” streams. The good news is that the creek’s populations of macroinvertebrates are improving in many areas.
Chris Dillmann/

This story has been corrected to better reflect the source of a 2021 water spill on Vail Mountain that resulted in a fish kill in Gore Creek.

Gore Creek in 2012 landed on the state’s list of “impaired waterways.” There’s good and bad news about efforts to restore the creek’s health.

The creek’s health starts with small bugs known as macroinvertebrates. Those bugs are at the base of the food chain for other aquatic life, particularly fish. Many of those bugs can be quite sensitive to environmental changes.

The caddisfly is among the macroinvertebrate species that’s particularly sensitive to environmental changes.
Town of Vail/courtesy photo

The Vail Town Council Tuesday heard a presentation from acquatic biologist David Rees and Vail Water Quality Education Coordinator Pete Wadden about the most recent data from continuing efforts to improve water quality in the creek.

Getting off the list

The ultimate goal is to get the creek off the state’s list, and the town and the Eagle River Water & Sanitation District have been working to do that, using education about fertilizer and pesticide use near the creek and trying to contain runoff of road sand and other contaminants. The town since 2016 has spent roughly $1 million per year on those efforts.

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Gore Creek through Vail is showing water quality improvements in many areas. That quality is measured by the presence of macroinvertebrates in the stream.
Chris Dillmann/

After years of effort, bug populations are improving in spots, but there are areas where the macroinvertebrate populations are lagging.

Some areas are starting to see comebacks by very sensitive species, Rees said. But, he added, one measurement method counts those species as a percentage of all macroinvertebrate life in a study area. By that method, the creek is still below levels needed to be within acceptable levels.

Still, Rees said, there are signs of improvement along stretches of creek in East Vail. Areas with more human impact have lower scores.

And, Wadden said, the creek is still seeing increases in a form of algae in the creek. Rees said that algae, a slippery goo that sticks to rocks in the streambed, is seen almost to the confluence of the Eagle River in Dowd Junction.

Success on Red Sandstone

Red Sandstone Creek is seeing some strong improvements. Wadden said that creek is seen as a “microcosm” of aquatic life in Gore Creek. That area saw some “targeted” education outreach regarding pesticide and fertilizer use, Wadden said.

But, he added, “We’re trying to pinpoint what’s changed. Whatever it is, we want to figure it out” for use on Gore Creek, Wadden said.

While the most recent study data comes from 2020, there were measurements taken in the wake of a 2021 fish kill in Gore Creek. That fish kill was linked to the draining of Vail Mountain’s snowmaking system. Water in the snowmaking reservoir (or “pond”) contained an algaecide Water in that pond contained an algaecide. That spill badly damaged macroinvertebrate life along a stretch of Gore Creek downstream from Mill Creek.

“Below the spill, everything was pretty much wiped out,” Rees said, adding that aquatic life above Mill Creek was already low.

Wadden added that the spill is still being investigated by state officials. And, he added, while the investigation has been going on for nearly six months, the probe is “moving at the speed of government,” Wadden said.

Mayor Kim Langmaid said the trends over time are encouraging. But there’s more work to be done to get Gore Creek’s water quality to match its appearance.

Good news, bad news

Good: Macroinvertebrate numbers are improving on Black Gore Creek.

Bad: Macroinvertebrate numbers are still low in improved areas along Gore Creek.

Bad: Last summer’s snowmaking system spill damaged aquatic life along portions of Gore Creek.

Good: The Eagle River below Dowd Junction still shows decent macroinvertebrate numbers in most places.

Source: Town of Vail

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