Potomac River fish kill: Thousands of dead fish found; officials say no link to sewage leak

MONTGOMERY COUNTY, Md. - Thousands of dead and dying fish were found along a several‑mile stretch of the Potomac River upstream from the massive sewage pipe rupture that sent millions of gallons of raw waste into the river in January.

The Maryland Department of the Environment says the fish kill is not connected to the Potomac Interceptor rupture and says there is no evidence of pollution. Officials believe the event is temperature‑related, noting water temperatures reached the mid‑90s when the die‑off began Friday and continued through the weekend.

They say extreme heat can create lethal conditions for some fish species and can also promote secondary bacterial infections in heat‑stressed fish. River flow in the area is about half of what is typical for July, but officials say they do not believe oxygen levels played a role.

One species, the golden redhorse suckers, accounted for most of the dead fish. The fish kill began Friday and by Sunday had either ended or significantly subsided.

To report a fish kill:

During Normal Work Hours: All incoming fish kill reports should be directed to the Maryland Department of the Environment's Fish Kill Investigation Section (443-482-2731) or (800-285-8195)

During Evenings, Weekends and Holidays: Calls should be directed to MEMA (1-866-633-4686). The dispatcher then immediately contacts the on call Duty Biologist from the MDE Fish Kill Response Program.