A water main break on Columbia Pike resulted in a mass fish kill in Four Mile Run this weekend.
The infrastructure failure took place on Saturday at Columbia Pike and S. Dinwiddie Street, county spokesperson Peter Golkin told ARLnow.
A tipster described cloudy water and at least hundreds of dead fish near the Shirlington dog park, about a mile and a half downstream of the Pike.
“The stream level is quite low, with very warm water, which is already stressful for fish because of diminished dissolved oxygen,” Golkin said. “A massive discharge of chlorinated water at a different temperature and oxygen level shocks and kills the fish very quickly.”
DES posted on social media about work on a 20-inch feeder main on the Pike, affecting about 100 water customers and blocking traffic in the area.
Emergency Water Main Repairs: Crew working on a 20-inch feeder main at Columbia Pike at S Dinwiddie. Some 100 customers could be affected. Traffic diverted around work site. Estimated time for completion: 2am. Questions: 703-228-6555. https://t.co/8YbKyxDQSg pic.twitter.com/NjZUHwFITd
— Arlington Department of Environmental Services (@ArlingtonDES) August 9, 2025
Repairs were completed early Sunday, Golkin said. He estimated that the break killed over a thousand fish.
“The state Department of Environmental Quality has been notified of this incident,” he said.
Golkin said that the water main break “was isolated in a little over an hour, having occurred at approximately 1:15 p.m. Saturday with service restored roughly an hour later when the pressure in the system had returned to normal ranges.”
“That’s super-fast work with kudos belonging to the Water, Sewer, Streets Bureau,” he noted.
