St. Mary's County, MD

ZIP 20636

In ZIP 20636, 5 of the 12 things we check have at least one part graded D or F.

• Drinking water: Fenwick Manor has 1 contaminant at or over an EPA legal limit; 6 contaminants are above health goals, led by arsenic at 3,417× California’s Public Health Goal.
• Nearest Superfund site: Patuxent River Naval Air Station, 2.2 miles away (2 within 10 miles).
• Largest share of modeled toxic air from industry: Stella-Jones Corp (62%), mostly arsenic compounds.
• Fine particles (PM2.5) average 6.9 µg/m³; the WHO guideline is 5 and the EPA annual standard is 9.
• About 64,785 kg of agricultural pesticides are applied in the county each year.

Grades for ZIP 20636

• Superfund sites nearbyA to F
• Factories and industrial sitesA to B
• Oil and gas wellsA
• Parks and nature nearbyC to D
• Air qualityA to B
• Drinking water qualityB to F
• Pesticide useD to F
• Neighborhood health statusB to D
• Past wildfire impactsA
• Past flood impactsC
• Noise levelsA
• Radiation signalsC

Based on 6 census tracts · compiled September 10, 2026 · how each grade works and its sources

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