Shortly before 10:00 am today, the City of Alexandria's Department of Transportation and Environmental Services (T&ES) received notification from Arlington County’s Department of Environmental Services concerning a fish kill event at Four Mile Run, located between Mount Vernon Avenue and Route 1. Witnesses reported a significant number of dead fish alongside live fish, reptiles, and waterfowl.

An investigation found a manual operation error at the County’s Water Pollution Control Plant that released higher-than-usual levels of sodium hypochlorite into the waterway late on March 12 as part of the regular wastewater treatment process. A correction was made in less than 90 minutes.

As of 2:00 pm today, water quality levels in Four Mile Run are returning to normal. There is no ongoing threat to Four Mile Run. Officials at the plant will review and refine procedures in coordination with the Virginia Department of Environmental Quality.

City staff responded to the area and are coordinating with the City’s Fire Marshal, HazMat, Arlington County, and the Virginia Department of Environmental Quality’s (DEQ) Northern Regional Office, which was contacted by Arlington staff. Arlington officials are addressing the Plant’s procedures in coordination with DEQ.