Yukon-Koyukuk County, AK

ZIP 99788

In ZIP 99788, 3 of the 12 things we check have at least one part graded D or F.

• Drinking water: Beaver Water System meets every EPA legal limit; 6 contaminants are above health goals, led by lead at 35× 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: Fort Knox Mine (99%), mostly chromium compounds.
• Fine particles (PM2.5) average 7.8 µg/m³; the WHO guideline is 5 and the EPA annual standard is 9.

Grades for ZIP 99788

• Superfund sites nearbyA
• Factories and industrial sitesA
• Oil and gas wellsA
• Air qualityC
• Drinking water qualityD to F
• Neighborhood health statusF
• Past wildfire impactsF
• Past flood impactsA

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

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