Fish found dead in Arlington stream were victims of chlorinated pool water, officials say

About 100 fish that turned up dead in a stream in Arlington County, Virginia, last week were the victims of chlorinated pool water that ended up in the county’s storm drains.

The Arlington Department of Environmental Services said on Twitter Monday that investigators had determined “flawed seasonal pool care involving chlorine and overflow” led to the fish kill in Four Mile Run, between South Walter Reed Drive and South Taylor Street.

Peter Golkin, spokesman for the department, said investigators traced the incident a multi-family housing property where a large amount of chlorine that had been added to a pool as part of seasonal maintenance.

The county has been in touch with the property management company and the pool company that did the maintenance work.

The storm drain system feeds directly into the county’s streams and there are no filters in the system; the department said recent rains have now cleared the stream.

The dead fish were discovered Sept. 7 — a few days after Labor Day, which is the end of the traditional summer pool season.

The department is reminding residents not to drain their pools directly into a storm drain unless they have taken the necessary steps to remove chlorine or bromine — another pool sanitizer — either by using removal agents or by allowing the untreated water to sit for about 10 days to allow chemicals to dissipate. A pool test kit should be used to make sure there aren’t any detectable levels of chlorine or bromine left.

Pool owners should also discharge the water slowly over a grassy area over the course of several days to allow the water to soak into the ground and reduce the amount that goes into storm drains.

Pool or spa water released over land should be at least 10 feet from the property line and monitored to make sure it doesn’t lead to flooding or erosion of neighboring properties.

The department said large amounts of water from pools and spas are typically discharged into the storm drain system during the spring and the fall and that it can have “devastating effects on the health of our streams.”

Jack Moore

Jack Moore joined as a digital writer/editor in July 2016. Previous to his current role, he covered federal government management and technology as the news editor at, part of Government Executive Media Group.

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