Arsenic
Unresolved Phase I/II/V Inorganic Chemical Rules violation cited in 2025 (arsenic).
PWSID CA3600123 · GroundwaterPrivate
112 people served. 9 health-based SDWIS violations recorded in the past 5 years. 14 remain unresolved. Last cited 1 year ago.
Unresolved Phase I/II/V Inorganic Chemical Rules violation cited in 2025 (arsenic).
Unresolved Phase I/II/V Inorganic Chemical Rules violation cited in 2025 (arsenic).
Unresolved Phase I/II/V Synthetic Organic Chemical Rules violation cited in 2025 (contaminant 7000).
Unresolved Phase I/II/V Inorganic Chemical Rules violation cited in 2025 (arsenic).
Health-based violations exceed an MCL or treatment-technique standard. Monitoring violations are reporting failures with no measured exceedance — they tell you the system isn't fully transparent, not that the water is unsafe today.
Maximum contaminant level exceeded
Maximum contaminant level exceeded
OTHER
Maximum contaminant level exceeded
Maximum contaminant level exceeded
OTHER
Maximum contaminant level exceeded
Maximum contaminant level exceeded
Maximum contaminant level exceeded
Maximum contaminant level exceeded
Treatment technique violation
Reporting failure
OTHER; returned to compliance
Failure to monitor as scheduled
Failure to monitor as scheduled
Barstow, California (Census place; block-group disparity scores aggregated by centroid containment): a service population of 25,235. Local disparity score for pm2.5 (fine particulate) sits moderately above the reference (135). Why we surface this →
Low-income
People of color
Under age 5
Over age 64
| Indicator | Disparity score | Reading |
|---|---|---|
| PM2.5 (fine particulate) | 135 | moderately above the reference |
| Ozone | 210 | severely above the reference burden |
| Nitrogen dioxide (NO₂) | 166 | well above the reference burden |
| Diesel particulate | 127 | moderately above the reference |
| Toxic releases (RSEI) | 20 | well below the reference |
| Traffic proximity | 98 | near the reference |
| Lead-paint risk (pre-1960 housing) | 110 | moderately above the reference |
| Superfund site proximity | 164 | well above the reference burden |
| RMP-facility proximity | 0 | well below the reference |
| Hazardous-waste site proximity | 114 | moderately above the reference |
| Underground storage tanks | 0 | well below the reference |
| NPDES wastewater proximity | 170 | well above the reference burden |
| Drinking-water non-compliance | 7 | well below the reference |
Source: Census ACS 2018-2022 (5-year) + USEPA-clone EJ blockgroup stats (raw indicators + EJ disparity mirror).
Source. EPA Safe Drinking Water Information System · retrieved 2026-05-07. Reporting period 2021-01-01 → 2026-05-07.
What this is not. SDWIS records compliance against federal MCLs — not a direct readout of tap-water concentrations. Active health-based violations are not the same as a current crisis; we link to the EPA record so you can verify return-to-compliance status before forming a conclusion.