Humboldt County, CA

ZIP 95521

In ZIP 95521, 4 of the 12 things we check have at least one part graded D or F.

• Drinking water: Mckinleyville C.s.d. meets every EPA legal limit; 6 contaminants are above health goals, led by bromodichloromethane at 82× 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: Pg&E Humboldt Bay Power Plant (100%), mostly acetaldehyde.
• Fine particles (PM2.5) average 9.5 µg/m³; the WHO guideline is 5 and the EPA annual standard is 9.
• About 15,274 kg of agricultural pesticides are applied in the county each year.

Grades for ZIP 95521

• Superfund sites nearbyA
• Factories and industrial sitesB to C
• Oil and gas wellsA
• Parks and nature nearbyA to C
• Air qualityD to F
• Drinking water qualityB to C
• Pesticide useB to D
• Neighborhood health statusA to D
• Past wildfire impactsA
• Past flood impactsA
• Noise levelsA to D
• Radiation signalsA to B

Based on 8 census tracts · compiled October 25, 2026 · how each grade works and its sources

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