Four Mile Run Safe After Overnight Fish Kill

Published on March 13, 2024

Water quality levels in Four Mile Run are returning to normal near Route 1 in Arlington after a fish kill – a sudden, unexpected death of a number of fish over a short period of time – occurred overnight.

An investigation found a manual operation error at the County’s Water Pollution Control Plant released higher-than-usual levels of sodium hypochlorite into the waterway late on March 12, 2024, as part of the regular wastewater treatment process. A correction was made in less than 90 minutes.

There is no ongoing threat to Four Mile Run.

Officials at the plant will review and refine procedures working with the Virginia Department of Environmental Quality.

Visit the County's Stream Safety page for more information.