Yukon-Koyukuk County, AK

ZIP 99777

In ZIP 99777, 3 of the 12 things we check have at least one part graded D or F.

• Drinking water: Nenana Municipal Water meets every EPA legal limit; 5 contaminants are above health goals, led by lead at 12× California’s Public Health Goal.
• Closer to Superfund sites than 54% 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 (98%), mostly chromium compounds.
• Fine particles (PM2.5) average 6.5 µg/m³; the WHO guideline is 5 and the EPA annual standard is 9.

Grades for ZIP 99777

• Superfund sites nearbyC
• Factories and industrial sitesA
• Oil and gas wellsA
• Air qualityA
• Drinking water qualityC to D
• Neighborhood health statusD
• Past wildfire impactsF
• Past flood impactsA
• Radiation signalsC

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

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