Arlington continues to monitor the recent sewage spills in the Potomac River, while noting that the County’s drinking water remains safe, regularly tested, and held to the highest state and federal standards.
Arlington’s water is treated at the Dalecarlia Water Treatment Plant run by the Washington Aqueduct, a division of the U.S. Army Corps of Engineers. The primary water intake to Dalecarlia (located upstream of the location of the sewage spill, near Great Falls) is not impacted by this spill.
As a precaution, Arlington Public Health (APH) Director, Dr. Deidra D. Parrish “agrees with VDH (Virginia Department of Health) that residents should avoid water recreational activity in the Potomac River."
VDH issued a recreational water advisory for the Potomac River. To prevent recreational water illnesses due to exposure to sewage spill events, people should:
* Avoid contact with water in the advisory area and observe advisory signage posted at waterbody access points.
* Avoid any area of the water body where water has a foul odor, dead or dying fish, or discolored water.
* Promptly wash skin with soap and water if you cannot avoid contact with water in the vicinity.
* Rinse or wash items that come into contact with the water, including clothing, fishing gear, life vests, ropes and paddles.
While the sewage discharge is not expected to impact Arlington’s stream water quality, the County’s bacteria monitoring program is collecting additional samples on Four Mile Run to supplement understanding of any impacts in the area. To date, this sampling has not shown an impact on Arlington streams, with low levels of E. coli bacteria.
Sewage Spill in the Potomac River
On Jan. 19, 2026, a portion of the Potomac Interceptor sewer line maintained by DC Water collapsed in Montgomery County, Md., causing an overflow of more than 200 million gallons of wastewater (raw sewage) into the Potomac River.
On Jan 27, DC Water installed a temporary bypass to reroute wastewater around the collapse and back into the District’s sewer lines. That bypass failed earlier this month when a number of pumps were clogged by “flushable” wipes flushed into the DC system. An enhanced bypass is set for completion within days, and DC Water expects to complete emergency repairs on the collapsed portion of the Potomac Interceptor in 4-6 weeks.
DC Water has published monitoring data at multiple locations along the Potomac River that show decreasing bacteria levels over time and with distance from the drainage channel. Residents should practice caution and follow advisories throughout the Potomac River corridor.
For updates on the repair status, visit DC Water https://www.dcwater.com/about-dc-water/media/potomac-interceptor-collapse For updates on Virginia impacts and to find links to the Maryland and DC agencies responding to this incident, visit VDH’s Sewage Spill in the Potomac River webpage.
Stream Safety
Arlington regularly cautions residents to use streams safely by avoiding swimming or full-body submersion for themselves and pets, due to E. coli bacteria from urban wildlife, pet waste, and other sources. Arlington stream monitoring has shown that bacteria levels are generally safe for wading and fishing and tend to be higher from May to October and in the 48 hours after a large rainstorm.