The Pennsylvania Department of Environmental protections suspects that a pesticide or herbicide is responsible for killing thousands of fish and other aquatic life along a portion of Chartiers Creek.
The DEP says they received a report of a "fish kill" in the creek near McMurray in Washington County last week.
Working with the PA Fish and Boat Commission, the DEP sent out inspectors and a biologist to the scene the day after the report.
The DEP says that the large number of dead fish happened along a 10-mile length of the creek.
Water samples were collected and while a pesticide is suspected, official results will not be available until July 30.
