San Luis Obispo County, CA

ZIP 93409

In ZIP 93409, 4 of the 12 things we check have at least one part graded D or F.

• Drinking water: California Mens Colony has 1 contaminant at or over an EPA legal limit; 16 contaminants are above health goals, led by nitrate at 20× https://journals.plos.org/water/article?id=10.1371/journal.pwat.0000329, https://www.polkcountyiowa.gov/media/lixlchbz/ciswra-currents-of-change_final-scientific-assessment-of-source-water-research-report_jun272025.pdf#page=222.
• 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: Phillips 66 Co-Santa Maria Refinery (97%), mostly benzene.
• Fine particles (PM2.5) average 5.4 µg/m³; the WHO guideline is 5 and the EPA annual standard is 9.
• About 901,427 kg of agricultural pesticides are applied in the county each year.

Grades for ZIP 93409

• Superfund sites nearbyA
• Factories and industrial sitesB
• Oil and gas wellsA
• Parks and nature nearbyD
• Air qualityA
• Drinking water qualityD
• Pesticide useF
• Neighborhood health statusC
• Past wildfire impactsF
• Past flood impactsC
• Noise levelsB
• Radiation signalsC

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

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