Twice a month, Metropolitan State University student biologists David Watson and Stephen Aderholdt have been slogging through contaminated Bear Creek testing the water, at work on a mystery of how its once-pure currents turned foul.
They’ve documented E.coli bacteria levels up to 19 times higher than the state health limit.
“Why is there so much E.coli? Where is it coming from?” Aderholdt, 31, said on the banks on a recent Saturday.
While government agencies have done their own testing and in 2008 deemed Bear Creek officially “impaired,” expanding data gathered by the students — trained by the Environmental Protection Agency and a community group called Groundwork Denver — may be crucial in crafting a cleanup.
Denver, Lakewood and Sheridan taxpayers would be on the hook, facing federal Clean Water Act penalties, if Bear Creek water quality isn’t improved.
This is a vexing problem because Bear Creek begins as a clear, clean trickle in wilderness snow atop 14,271-foot Mount Evans, visible to residents around metro Denver. The creek cascades through forests unsullied.
But starting in foothills near Evergreen, pristine water reaches suburban homes, roads, reservoirs, septic tanks, parks used by dog-walkers, golf courses, commercial sites. Denver Environmental Health water quality scientist Jon Novick, a public health analyst, said contamination is worst as Bear Creek approaches the South Platte River, which also is contaminated with E.coli and other pollutants.
Watson and Aderholdt have recorded E.coli contamination in Bear Creek as high as 2,400 colony-forming units (cfus) per 100 milliliters. The state health limit is 126 cfus.
The data collected by the Metro State team is useful, Novick said.
“It is helpful to understand where E.coli levels are increasing and the potential sources,” he said.
Denver conducts its own tests on the creek, four times a year, and has documented E.coli during summer as high as 770 cfu.
The Metro State students conduct tests at 18 locations twice a month. They started in May 2013. The work can be difficult, clambering up and down muddy banks, kicking through ice during winter. (Bear Creek E.coli levels during winter, when E.coli often decreases, have veered above the limit as high as 325 cfu.)
Watson and Aderholdt’s boots sink into creek-bottom muck as they stand in the creek, first measuring temperature and turbidity, then filling two clear containers. They cover an 8.2- mile stretch of the creek from the South Platte to Bear Creek Reservoir.
EPA scientists who trained them analyze the samples in a federal lab and review the data for accuracy. They occasionally accompany the students and Groundwork Denver supervisor Rachel Hansgen, who also coordinates community-driven water-sampling along other creeks and rivers.
EPA project manager Karl Hermann, a senior water quality analyst, said he’s been impressed with students’ seriousness over more than a year and sees their monitoring data as helpful in moving toward a solution that could avert penalties.
Bear Creek has remained on Colorado’s list of impaired waterways for years, Hermann said. Ramped-up EPA lab work this year, using the expanding data, may help pin-point sources of the pollution.
E.coli indicates a variety of different bacteria that come from people and animals. When E.coli levels exceed 235 cfu, the Colorado Department of Public Health and Environment orders waterways closed for swimming.
“We know dogs are involved and that humans are involved,” Hermann said. “We don’t have wastewater treatment plants along Bear Creek. If there’s a human element, it may be septic systems that are not working quite right. We have a number of other possibilities.”
University and community science groups, when trained, can make a difference, he said.
“There are protocols. Groundwork Denver and Metro State have gone through the process of learning to do things right,” Hermann said. “They’ve refined their methods and we are really happy with the collaborative approach.”
Groundwork Denver staffers also are developing a restoration plan for the Lower Bear Creek watershed, where greenway trails already are established. They’re hoping, if all goes well and the creek can be cleaned, that this plan will be a model for dealing with contaminated urban waterways, Hansgen said.
“The scientific method is something we use purposefully,” she said. “This is work that needs to be done.”