Parts of Boulder Creek still impaired because of elevated levels of E. coli

May 14—Sections of Boulder Creek are still considered "impaired" because of elevated levels of E. coli in the water and people recreating in the creek should continue to take precautions, according to state and city officials.

The Colorado Department of Public Health and Environment designated a stretch of Boulder Creek from the mouth of Boulder Canyon through Boulder's Eben G. Fine Park as impaired in December 2019, and that assessment has not changed.

"The state evaluated the data this past year and determined that Boulder Creek is still impaired. Additionally, the state found Rock Creek, a tributary downstream of the city, is also impaired," CDPHE spokesperson MaryAnn Nason said in a statement.

Boulder city officials continue to monitor the creek's water quality, said Candice Owen, program supervisor for stormwater quality.

"We see the same seasonal pattern year over year that hasn't really changed a lot," Owen said. "Later in the summer, flows are lower and temperatures are warmer and concentrations go up, and then they fall back down in the late fall, winter and spring."

The city is continuing its program to better understand sewer sheds and creek inflow, Owen said, though it continues to be a "very challenging problem" not only in Boulder, but across the state.

City officials cannot prevent people from entering the creek, but the city has installed signs cautioning people about entering the water, Owen said.

If people choose to recreate in the creek, they should avoid it after a rainstorm, avoid getting creek water in the eyes or mouth, don't go in with open wounds and wash off after swimming or recreating.

"There are actions you can take to be safe and try to mitigate risk when you're recreating," Owen said. "There are also actions we can all take, like picking up dog waste and not over-irrigating, which prevents E. coli from reaching the creek in the first place."

The state continues to monitor Boulder's progress on reducing E. coli levels, Nason said, and will likely reevaluate water quality in 2023 and updating the creek's impairment status in 2025.