UPDATED: Four Mile Run Stream Advisory Lifted

Published on October 31, 2019

Update 11/5/19: The source of the petroleum release has been mitigated and the impacted area has been cleaned up. The advisory to avoid contact with the stream has been lifted after monitoring the stream for several days. The County recommends residents resume adherence to its normal protective guidelines for interacting with urban streams. More information can be found on the Department of Environmental Services' Stream Safety page




Update 11/1/19: The source of the petroleum release on Oct. 31 has been identified. The chemical is heating oil from an improperly abandoned tank.  Cleanup is underway and the State DEQ is involved with the incident. 




Residents and visitors are advised to avoid contact with — and keep their pets out of — Four Mile Run downstream of Columbia Pike for the next 24 to 48 hours.

At 6:29 a.m. Thursday, Oct. 31, Arlington County Hazmat Crews were dispatched to the 4200 block of S. Four Mile Run Drive for a chemical odor. The Arlington County Fire Department and the Arlington Department of Environmental Services determined that the source originated at the border of Arlington County. Crews placed boom filtering devices in the water at various locations along Four Mile Run to contain the released product.

Public, pets, should stay out of Four Mile Run


People should not fish in the stream or have any contact with the water until further notice from the County. The advisory to avoid all contact is considered an extra precaution to allow the effect of the discharge to be diminished by natural flushing of the streams.

Drinking water is not affected by the incident.


Anyone who has been in Four Mile Run and is experiencing medical symptoms, such as sore throat or eye irritation, should seek medical attention.

NOTE: The public is  reminded that stream water can contain microorganisms that can make people sick, whether the stream is located in an urban area or in the middle of a forest. Even after the discharge is naturally flushed from the streams, the County's normal precautions for safe use of streams apply. You can find information and safety tips on Arlington streams, including information on reporting stream pollution incidents, on the Department of Environmental Service website.