Elevated levels of per- and polyfluoroalkyl substances — commonly called PFAS — have been discovered in a stormwater pond and a nearby stream in Montgomery County, Maryland, prompting authorities to issue a health advisory urging residents and their pets to stay out of the affected waterways.
Where the Contamination Was Found
The affected waterways sit near the intersection of Great Seneca Highway and Key West Avenue in the Gaithersburg and Rockville area, close to where Decoverly Drive crosses Great Seneca Highway. The contaminated water runs alongside Shady Grove Hospital along Great Seneca Highway and continues past Muddy Branch Road. County crews have placed red temporary fencing around the contaminated pond to restrict access.
Officials are advising residents to avoid any contact with the impacted waterways, keep animals away from the area, and refrain from eating fish caught there. Free PFAS testing is being offered to owners of private wells in the vicinity, and additional sampling is underway to determine how far the contamination has spread.
Source Traced to Former Training Facility
County environmental officials say the PFAS likely entered the waterways through firefighting foam that was used at a former public safety training facility that operated in the area until 2015. Jennifer Macedonia, Director of the Montgomery County Department of Environmental Protection, confirmed that state testing turned up high PFAS concentrations “in an area on and adjacent to the site of the county’s former public safety training facility.”
PFAS chemicals, sometimes called “forever chemicals” because they break down very slowly in the environment and in the human body, have been the subject of growing federal and local scrutiny. Their presence in firefighting foam — particularly aqueous film-forming foam, or AFFF — has been linked to contamination at military bases, airports, and public training sites across the country.
Tap Water Declared Safe
Despite the environmental find, county officials and water utility representatives are drawing a clear distinction between the affected surface water and the public drinking supply. Laura O’Donnell, PFAS Program Manager for WSSC Water, said customers in Montgomery and Prince George’s counties can be confident that “the water we provide is safe.” County officials echoed that reassurance, stating that municipal tap water does not appear to be affected by the contamination found in the pond and stream.
County Already in Legal Battle With Manufacturers
Montgomery County filed a lawsuit in 2023 against companies that manufactured PFAS chemicals, seeking to hold them financially responsible for cleanup and related damages. The discovery of elevated PFAS levels in local waterways adds urgency to that ongoing legal action and may factor into the scope of remediation the county ultimately pursues.
Broader PFAS Concerns and Idaho Parallels
The Montgomery County situation reflects a pattern unfolding in communities across the United States, where legacy use of PFAS-containing firefighting foams at public facilities has left a long-term contamination footprint. Federal agencies including the EPA have moved in recent years to establish enforceable drinking-water limits for several PFAS compounds, a regulatory shift that has drawn both support and scrutiny.
Idaho communities have faced their own questions about water quality and chemical exposure. Decisions about what goes into — or comes out of — public water systems remain an active policy conversation across the state. Earlier this year, an Alabama city voted to halt fluoride addition to its municipal water supply, reflecting a broader public appetite for closer scrutiny of what communities allow in their drinking water.
For residents near the Gaithersburg and Rockville area, the immediate priority is avoiding contact with the flagged waterways while county and state officials work to define the full extent of the contamination and chart a remediation path forward.
Category: Toxins & Environment