Tiny bugs disappearing from Vail’s Gore Creek

VAIL, Colorado – Something is hurting the tiny bugs in Gore Creek, but researchers aren’t sure what.

A recent study revealed certain bugs are disappearing in the East Vail stretch of the stream.

The bugs present in low numbers – certain mayflies, stoneflies and caddisflies – are especially sensitive to the effects of urbanization, said David Rees, a bug expert processing the study data.

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And their absence is a sign that something is damaging this popular trout-fishing stream, which runs through a tourist town that prides itself on its natural beauty.

“A large portion of our economy depends on this perception that this is a pristine area,” said Linn Brooks, assistant general manager for the Eagle River Water and Sanitation District.

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The water district discovered the bug problem while studying the creek and nearby Eagle River. Brooks said the bug trouble was most noticeable east of Vail.

“It seems like there is so much natural land around here and to have what appear to be urban impacts on Gore Creek, in East Vail where it’s not even than urban, just really surprised us,” she said.

Something has been causing a change in the stream’s macroinvertebrates, the tiny bugs that live in the rocks, Rees said. There are fewer types of bugs overall than one expects to see in a mountain stream, Rees said.

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While some bugs are dwindling, others are more plentiful then normal, he said. Midges and worms, which are less sensitive to environmental stress, are abundant.

“Whenever we see this change in the composition, it’s an indication there’s stress,” he said.

Although Vail is famous for its natural beauty, fishermen sometimes joke that “A Highway Runs Through it,” – referring to the cult fly-fishing movie “A River Runs Through it.”

Gore Creek runs parallel to Interstate 70. To keep Vail Pass safe, the Colorado Department of Transportation sprays traction sand on the roads, Brooks said.

Although CDOT has taken steps to prevent that sand from washing into Gore Creek, including building collection ponds, sand from years go may still be causing problems, she said.

John Woodling, a retired fish biologist familiar with the stream, agrees sand is a likely culprit.

The sand settles over the rocks and fills up the space where the bugs live, he said. Although CDOT has been working to contain the sand, there is still plenty left on the hillside, he said.

“There’s decades worth of sand that’s working its way through the system,” he said.

Brooks said the water district plans to investigate other theories, too. One holds that fertilizers and lawn chemicals are hurting the creek.

“There are places where people’s lawns literally come right up to the rocks at the edge of the water,” she said.

Another theory claims road gunk that washes into the stream has been changing its makeup.

While urbanization threatens streams everywhere, Gore Creek might be especially sensitive, Brooks said.

“It may be that Gore Creek is a more fragile stream and it just can’t handle it like other places can,” she said.

Fishermen out there might be wondering: What does all this mean for the trout?

“The situation of the bugs does raise the question of: How are the fish doing?” said Melissa Macdonald, executive director of the Eagle River Watershed Council.

There’s no direct link between the number of macroinvertebrates and the number of fish, Woodling said.

Although fish do eat the bugs in the rocks, they also snap up bugs that fall into the water. The fish could still find plenty of grub in the form of beetles, ants and other bugs that fall in the creek.

“One good grasshopper is worth a whole bunch of aquatic bugs,” Woodling said.

Indeed, John Packer, owner of Fly Fishing Outfitters in Avon, said the fishing is good on the upper stretch of Gore Creek.

“This whole past summer, people were hooking a lot of fish up there, healthy fish too,” he said.

The fishery was in good condition in 1998, the last time researchers conducted a formal survey. Kendall Bakich, aquatic biologist for the Colorado Division of Wildlife, said the state plans to study the fish in Gore Creek next summer.

Interestingly, the bug problem gets better about where the stream’s gold medal rating begins.

The division of wildlife has assigned the gold rating to Gore Creek between the Eagle River and Red Sandstone Creek (just east of Cascade Village). The rating means the stream has a high potential for trophy trout, said Randy Hampton, a spokesman for the division of wildlife.

Although the bugs could have something to do with that, Woodling points out that the gold rating starts about where the Vail wastewater plant starts discharging treated water. The nutrients in the water could help the fish, he said.

While the bug problem may not have a direct affect on the trout in Gore Creek, it’s still a compelling mystery to those who study it.

“It makes us want to figure out why the bugs are not there, what’s causing it, and is this something that’s going to get worse?” Macdonald said.

Given Gore Creek’s reputation as a trout mecca, researchers were surprised to find the bugs are actually healthier in the nearby Eagle River.

The water district discovered the bug problem while studying the effects of treated wastewater on the Eagle River. The water district runs wastewater treatment plans in Vail, Avon and Edwards, all of which discharge nutrients into the water.

The study suggests that nutrients such as nitrogen and phosphorous – which in large quantities can cause algae overgrowth that stifles the bugs – do not appear to be hurting the macroinvertebrates in the stretch of water from Vail to Edwards, Brooks said.

The state is coming up with new regulations for the nutrients wastewater treatment plants discharge, Brooks said.

The water district volunteered to do the study to help explore the complex relationship between nutrients and river health, she said. Researchers collected samples at 18 locations along Gore Creek and the Eagle River in fall 2008 and spring 2009, Brooks said. They are still processing the results of samples they took in fall 2010, she said.

Brooks expects The Colorado Water Quality Control Division to come out with new rules for nutrient discharge by June 2011. It could cost the water district $10 million to $20 million to remodel the local treatment plants to comply with the regulations, she said.

Staff Writer Sarah Mausolf can be reached at 970-748-2928 or smausolf@vaildaily.com.