Custer County, MT

ZIP 59301

In ZIP 59301, 7 of the 12 things we check have at least one part graded D or F.

• Drinking water: Ashland Water And Sewer Dist has 1 contaminant at or over an EPA legal limit; 8 contaminants are above health goals, led by lead at 22× California’s Public Health Goal.
• Closer to Superfund sites than 0% of U.S. neighborhoods, with no listed site within 10 miles of its center.
• Largest share of modeled toxic air from industry: Colstrip Energy LP Rosebud Power Plant (90%), mostly chromium compounds.
• Fine particles (PM2.5) average 5.4 µg/m³; the WHO guideline is 5 and the EPA annual standard is 9.
• About 66,519 kg of agricultural pesticides are applied in the county each year.

Grades for ZIP 59301

• Superfund sites nearbyA
• Factories and industrial sitesA to B
• Oil and gas wellsA
• Parks and nature nearbyB to F
• Air qualityA
• Drinking water qualityD
• Pesticide useF
• Neighborhood health statusC to F
• Past wildfire impactsA to F
• Past flood impactsA
• Noise levelsA to D
• Radiation signalsD to F

Based on 11 census tracts · compiled September 10, 2026 · how each grade works and its sources

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