Ingredients in a product that leaked into a Chester County stream are toxic to aquatic life, officials say

The individual ingredients that make up the final product of a “milky white” substance that leaked into a Chester County creek last week are toxic to aquatic life, killing fish, eels, and worms, the Pennsylvania Department of Environmental Protection said.

But county health officials said the materials released into the creek are not known to have acute or chronic human health risks. The department still advised people and pets to avoid “affected areas of Goose Creek to reduce impacts on the ongoing cleanup efforts.”

The leak, which was discovered after several people called West Chester officials about “noticeable pollution” in Goose Creek, was plugged last Saturday. It stemmed from Atmos Technologies, at 216 Garfield Ave. in West Goshen Township, near Henderson High School. It is unclear how long the outfall pipe had been leaking before people reported it.

Atmos Technologies told the state agency chlorinated water was released to a containment area, mixing with a manufactured product known as “Long Duration Foam AC-645,” forming a foaming agent, DEP officials said last week. The county’s health department said 4,000 gallons of the mixture was released.

Since its discovery, DEP staff have visited Goose Creek, most recently on Wednesday, and observed cleanup efforts at Atmos and along Goose Creek. The creek was clear Wednesday, with some foam accumulation present on debris, said Robyn Briggs, a spokesperson for DEP. The outfall pipe remained plugged, she said.

People had reported a fish kill — the mass death of fish due to pollution or environmental stress — but as of Thursday, no dead fish had been seen at the end of DEP’s tracing area.

West Goshen and West Chester officials said last week that Atmos Technologies could face fines for the leak. The company said in a statement last week that the chemical is nontoxic and used in environmental cleanups.

“The material breaks down naturally and is not expected to have any long-term impact on local wildlife or the ecosystem,” the company wrote.

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