State officials are investigating what killed thousands of fish in Chartiers Creek in Washington and Allegheny counties last week.
Lauren Fraley, a spokesperson for the Southwest Regional Office of the state Department of Environmental Protection, said Monday that the DEP has not determined a cause, but suspects pesticide or herbicide application.
Investigators estimate that thousands of fish of many species, including carp, crayfish, minnows and suckers, have died along an approximately 10-mile stretch of Chartiers Creek near McMurray.
The DEP and the Pennsylvania Fish and Boat Commission began an investigation Thursday after the DEP received a phone call earlier in the afternoon about a fish kill. The investigation continued Friday, when the DEP collected water samples.
Lab results are expected by July 30, according to Fraley.