Middlesex County, MA

ZIP 01721

In ZIP 01721, 6 of the 12 things we check have at least one part graded D or F.

• Drinking water: Holliston Water Department has 1 contaminant at or over an EPA legal limit; 13 contaminants are above health goals, led by pfos at 3.7× California’s Public Health Goal.
• Nearest Superfund site: Nyanza Chemical Waste Dump, 1.3 miles away (2 within 10 miles).
• Largest share of modeled toxic air from industry: Isomedix Operations Inc. (24%), mostly chromium compounds.
• Fine particles (PM2.5) average 6.2 µg/m³; the WHO guideline is 5 and the EPA annual standard is 9.
• About 34,462 kg of agricultural pesticides are applied in the county each year.

Grades for ZIP 01721

• Superfund sites nearbyF
• Factories and industrial sitesC to D
• Oil and gas wellsA
• Parks and nature nearbyC to D
• Air qualityA
• Drinking water qualityA to F
• Pesticide useB to D
• Neighborhood health statusA to C
• Past wildfire impactsA
• Past flood impactsC
• Noise levelsA to C
• Radiation signalsD

Based on 5 census tracts · compiled September 10, 2026 · how each grade works and its sources

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