Williamson County, TX

ZIP 78642

In ZIP 78642, 3 of the 12 things we check have at least one part graded D or F.

• Drinking water: Durham Park Wsc meets every EPA legal limit; 8 contaminants are above health goals, led by lead at 36× 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: Samsung Austin Semiconductor (77%), mostly chlorine.
• Fine particles (PM2.5) average 7.3 µg/m³; the WHO guideline is 5 and the EPA annual standard is 9.
• About 204,705 kg of agricultural pesticides are applied in the county each year.

Grades for ZIP 78642

• Superfund sites nearbyA
• Factories and industrial sitesA
• Oil and gas wellsA to C
• Parks and nature nearbyB to C
• Air qualityB to C
• Drinking water qualityD to F
• Pesticide useC to F
• Neighborhood health statusB to D
• Past wildfire impactsA
• Past flood impactsA
• Noise levelsA to B
• Radiation signalsB to C

Based on 7 census tracts · compiled September 10, 2026 · how each grade works and its sources

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