West Lebanon, New Hampshire, within the 03784 zip code, currently carries a critical environmental hazard designation. This severe classification stems primarily from its extreme proximity to the Mahan Street Site, an active Environmental Protection Agency remediation zone located just 0.6 miles from residential centers. A second active facility, the US Army Cold Regions Research and Engineering Laboratory, lies 5.5 miles away, compounding regional exposure profiles.

The primary pollutants at the Mahan Street Site are currently classified as unspecified hazardous substances. When environmental regulators designate contaminants as unspecified, it indicates a complex mixture of industrial or chemical waste. Exposure to these undefined toxic aggregates poses severe, unpredictable health risks to the local population. Depending on the exact chemical composition, residents face potential systemic health impacts ranging from acute respiratory irritation and neurological impairment to long-term carcinogenic effects. These compounds typically migrate through subterranean groundwater aquifers or become airborne during soil disturbance.

The Mahan Street Site maintains an active National Priorities List status, indicating that the EPA is presently conducting ongoing investigation, containment, or active cleanup operations. Because remediation is incomplete, the risk of ambient exposure remains elevated. Residents should immediately test private well water for volatile organic compounds and heavy metals through a certified state laboratory. Individuals relying on municipal water should install high-efficiency reverse osmosis filtration systems at the point of use to intercept potential pipeline infiltration. Finally, property owners should strictly avoid deep soil excavation or unauthorized land disturbance, which could aerosolize dormant chemical particulate matter.