Boulder County, CO

ZIP 80305

In ZIP 80305, 7 of the 12 things we check have at least one part graded D or F.

• Drinking water: Eldorado Municipal System meets every EPA legal limit; 4 contaminants are above health goals, led by arsenic at 1,900× California’s Public Health Goal.
• Nearest Superfund site: Marshall Landfill, 0.5 miles away (2 within 10 miles).
• Largest share of modeled toxic air from industry: Terumo Bct Sterilization Services Inc (87%), mostly ethylene oxide.
• Fine particles (PM2.5) average 6.7 µg/m³; the WHO guideline is 5 and the EPA annual standard is 9.
• About 17,327 kg of agricultural pesticides are applied in the county each year.

Grades for ZIP 80305

• Superfund sites nearbyD to F
• Factories and industrial sitesC to D
• Oil and gas wellsA to B
• Parks and nature nearbyB to D
• Air qualityA to B
• Drinking water qualityC to D
• Pesticide useC to D
• Neighborhood health statusA to B
• Past wildfire impactsA
• Past flood impactsC to D
• Noise levelsA to B
• Radiation signalsD

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

Loading the full report, with every source…