Test results revealed a fungicide was present in Chartiers Creek on July 15, when neighbors reported a fish kill along a stretch of the creek in Washington and Allegheny counties, according to the state Department of Environmental Protection.
The DEP initially suspected a pesticide or herbicide application as the cause of the fish kill, which resulted in deaths of thousands of fish that encompassed a 10-mile stretch of Chartiers Creek that started at Valley Brook Road in Peters Township and continued downstream.
Results from initial sampling taken on July 15 showed no traces of pesticide, but tested positive for fungicide, a chemical used to kill or prevent the growth of fungus.
The Washington County Watershed Alliance estimates tens of thousands of fish, including small mouth bass, died in the event.
DEP spokeswoman Lauren Fraley said the agency is waiting for results from samples taken between July 19 and 26 to help assess the creek’s recovery and any lasting impacts the spill might have.
“However, during inspections of the stream the weeks of July 19 and 26, DEP observed fish and aquatic life starting to repopulate the affected area,” Fraley said in an email.
She said no evidence of fungicide or other pollutants remains in Chartiers Creek in the area of the spill that indicate any further impact on aquatic life.
“It will, however, take time for the stream to restore the aquatic community that existed before the spill,” Fraley said in the email.
The DEP declined to comment on the potential source or sources of the fungicide.
The fish kill was reported July 15, but the DEP believes the fungicide entered the water the day before.
Fraley said a delay between the time the incident reportedly occurred and the time it was reported “has been a significant impediment to DEP’s investigation.”
DEP encourages the public to report fish kills, pollution events, or other issues of concern on waterways directly to DEP.
Those who observe environmental problems are asked to call the DEP Southwest Regional Office at 412-442-4000.