Lewis and Clark County, MT

ZIP 59623

In ZIP 59623, 4 of the 12 things we check have at least one part graded D or F.

• Drinking water: Helena Water System has 3 contaminants at or over an EPA legal limit; 18 contaminants are above health goals, led by lead at 13× California’s Public Health Goal.
• Nearest Superfund site: East Helena Site, 8.0 miles away (2 within 10 miles).
• Largest share of modeled toxic air from industry: American Chemet Corp (89%), mostly copper compounds.
• Fine particles (PM2.5) average 5.7 µg/m³; the WHO guideline is 5 and the EPA annual standard is 9.
• About 26,812 kg of agricultural pesticides are applied in the county each year.

Grades for ZIP 59623

• Superfund sites nearbyD
• Factories and industrial sitesB
• Oil and gas wellsA
• Parks and nature nearbyB
• Air qualityA
• Drinking water qualityC to D
• Pesticide useD
• Neighborhood health statusB
• Past wildfire impactsA
• Past flood impactsA
• Noise levelsA
• Radiation signalsF

Based on 1 census tract · compiled September 10, 2026 · how each grade works and its sources

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