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Boulder officials say an area of Boulder Creek where hundreds of fish have been killed by the spill of an unknown substance is now safe for swimmers and pets.

In the past two days, about 200 dead fish have been found in the area between Millennium Harvest House hotel and 28th Street.

Officials initially said they were keeping people away from the area, but are now confident that the spill isn’t harmful to humans or other animals.

Environmental officials are still waiting for test results to confirm what spilled into the creek, apparently near Folsom Avenue.

Initial indications, according to officials, are that a fine sediment caused oxygen levels in the water to drop. Chemicals are not suspected.

“Until we finish the investigation, we can’t say anything definitive,” city spokesman Mike Banuelos said Friday afternoon.

Banuelos said the tests should be completed sometime early next week.

Larry Rogstad, an area wildlife manager for the Colorado Division of Wildlife, said the kill seems to be isolated within a few hundred yards in both directions of the creek, centering at 28th Street.

“We have healthy fish swimming upstream and downstream from both directions” outside of the dead area, Rogstad said.

He said most of the dead fish are brown trout, along with some white suckers.

Local fishermen, Rogstad said, reported diminished water flow about a day ago when the fish began dying. The lower water flow, coupled with possible sediment increases, may have starved the fish of oxygen.

Nathan Bolser, 28, was the first to report the die-off after checking out one of his favorite fishing spots on an afternoon run.

“It’s a good hole that holds a lot of fish,” the Lyons resident said. “I am glad that the city’s looking into it.”

Contact Camera Staff Writer Heath Urie at 303-473-1328 or

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