Jefferson County, MT

ZIP 59631

In ZIP 59631, 6 of the 12 things we check have at least one part graded D or F.

• Drinking water: Rocky Mountain Wua has 1 contaminant at or over an EPA legal limit; 2 contaminants are above health goals, led by uranium at 4,354× California’s Public Health Goal.
• Nearest Superfund site: Basin Mining Area, 5.7 miles away.
• Largest share of modeled toxic air from industry: Ash Grove Cement Co Montana City Plant (36%), mostly chromium.
• Fine particles (PM2.5) average 5.2 µg/m³; the WHO guideline is 5 and the EPA annual standard is 9.
• About 10,384 kg of agricultural pesticides are applied in the county each year.

Grades for ZIP 59631

• Superfund sites nearbyF
• Factories and industrial sitesA
• Oil and gas wellsA
• Parks and nature nearbyB
• Air qualityA
• Drinking water qualityD to F
• Pesticide useD
• Neighborhood health statusD
• Past wildfire impactsD
• Past flood impactsA
• Noise levelsC
• Radiation signalsF

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

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