King County, WA

ZIP 98166

In ZIP 98166, 5 of the 12 things we check have at least one part graded D or F.

• Drinking water: Highline Water District has 1 contaminant at or over an EPA legal limit; 14 contaminants are above health goals, led by pfos at 5.1× California’s Public Health Goal.
• Nearest Superfund site: Seattle Municipal Landfill (kent Highlands), 4.3 miles away (3 within 10 miles).
• Largest share of modeled toxic air from industry: Puget Sound Coatings (52%), mostly diisocyanates.
• Fine particles (PM2.5) average 6.8 µg/m³; the WHO guideline is 5 and the EPA annual standard is 9.
• About 17,223 kg of agricultural pesticides are applied in the county each year.

Grades for ZIP 98166

• Superfund sites nearbyF
• Factories and industrial sitesD to F
• Oil and gas wellsB to C
• Parks and nature nearbyC to F
• Air qualityB
• Drinking water qualityC to F
• Pesticide useB to C
• Neighborhood health statusC
• Past wildfire impactsA
• Past flood impactsA
• Noise levelsA to D
• Radiation signalsB

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

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