Williamson County, TX

ZIP 78664

In ZIP 78664, 7 of the 12 things we check have at least one part graded D or F.

• Drinking water: Jonah Water Sud has 3 contaminants at or over an EPA legal limit; 19 contaminants are above health goals, led by pfos at 5.4× 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: Tesla Giga Texas (73%), mostly polycyclic aromatic compounds.
• Fine particles (PM2.5) average 8.7 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 78664

• Superfund sites nearbyA
• Factories and industrial sitesC
• Oil and gas wellsC to D
• Parks and nature nearbyD
• Air qualityC to F
• Drinking water qualityC to F
• Pesticide useC to F
• Neighborhood health statusA to C
• Past wildfire impactsA
• Past flood impactsB
• Noise levelsA to D
• Radiation signalsC to D

Based on 20 census tracts · compiled September 10, 2026 · how each grade works and its sources

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