Ocotillo Oasis, Llc Water Quality — San Marcos, California

Who Drinks This Water

San Marcos, California (Census place; block-group disparity scores aggregated by centroid containment): a service population of 94,360. Local disparity score for pm2.5 (fine particulate) sits moderately above the reference (139). Why we surface this →

NATIONAL PERCENTILE · vs all US block groups (population-weighted; ranked against the national EJScreen indicator distribution)

• PM2.5 (fine particulate)iHealth riskFine inhalable particles 2.5 micrometers or smaller. They travel deep into the lungs and into the bloodstream — linked to asthma, heart disease, stroke, and premature death.93in the highest 10% nationally
• OzoneiHealth riskGround-level ozone (smog) inflames the airways. Even short exposures trigger asthma attacks and worsen chronic lung and heart disease.82in the highest 20% nationally
• Nitrogen dioxide (NO₂)iHealth riskA tailpipe and combustion gas. Concentrates near busy roads and industrial sites; raises risk of airway inflammation, asthma, and lower respiratory infections in children.44near the national median
• Diesel particulateiHealth riskSoot from diesel engines (trucks, trains, ports, construction). EPA classifies it as a likely human carcinogen and a major driver of childhood asthma near freight corridors.59near the national median
• Toxic releases (RSEI)iHealth riskEPA's Risk-Screening Environmental Indicators score — weights TRI chemical releases by toxicity, where they go, and how many people are nearby. Higher means greater modeled cancer and chronic-health risk.20below the national median
• Traffic proximityiHealth riskPopulation-weighted distance to high-volume roads. Living close to heavy traffic raises exposure to PM2.5, NO₂, and diesel exhaust — and the cardiovascular and asthma risks that follow.73above the national median
• Lead-paint risk (pre-1960 housing)iHealth riskShare of housing built before 1960, when lead-based paint was common. Dust from deteriorating paint is the leading cause of childhood lead poisoning, which permanently impairs cognitive development.27below the national median
• Superfund site proximityiHealth riskPopulation-weighted distance to NPL Superfund sites — the most contaminated waste sites in the country. Nearby groundwater, soil, and air can carry industrial solvents, metals, and other long-lived contaminants.56near the national median
• RMP-facility proximityiHealth riskDistance to facilities holding chemicals at quantities large enough to require an EPA Risk Management Plan (refineries, fertilizer plants, etc.). These pose acute exposure risk during accidental releases.42near the national median
• Hazardous-waste site proximityiHealth riskDistance to RCRA hazardous-waste handlers (treatment, storage, disposal facilities). Indicates potential exposure to industrial chemicals in air, soil, and groundwater.88in the highest 20% nationally
• Underground storage tanksiHealth riskDensity of underground tanks (gasoline, heating oil, industrial fluids). Leaking tanks are a leading source of benzene and other volatile organic compounds in groundwater drinking-water supplies.28below the national median
• NPDES wastewater proximityiHealth riskDistance to permitted industrial wastewater dischargers. Closer proximity raises exposure to pollutants released into surface waters used for fishing, recreation, and downstream drinking-water intakes.69above the national median
• Drinking-water non-complianceiHealth riskEPA score for public water systems with health-based Safe Drinking Water Act violations. Higher means more residents on systems that recently exceeded safe limits for contaminants like lead, arsenic, or nitrate.76above the national median