Plymouth County, IA

ZIP 51031

In ZIP 51031, 7 of the 12 things we check have at least one part graded D or F.

• Drinking water: Sioux City Water Supply has 2 contaminants at or over an EPA legal limit; 22 contaminants are above health goals, led by lithium at 19× the USGS health-based screening level.
• Nearest Superfund site: Highway 3 PCE, 1.5 miles away.
• Largest share of modeled toxic air from industry: Little Sioux Corn Processors LLC (60%), mostly acrolein.
• Fine particles (PM2.5) average 6.7 µg/m³; the WHO guideline is 5 and the EPA annual standard is 9.
• About 420,419 kg of agricultural pesticides are applied in the county each year.

Grades for ZIP 51031

• Superfund sites nearbyC to F
• Factories and industrial sitesB to C
• Oil and gas wellsA
• Parks and nature nearbyD
• Air qualityA to B
• Drinking water qualityC to F
• Pesticide useF
• Neighborhood health statusB to C
• Past wildfire impactsA
• Past flood impactsC to F
• Noise levelsA to D
• Radiation signalsD

Based on 8 census tracts · compiled September 10, 2026 · how each grade works and its sources

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