County · California
Mariposa County, California: drinking water records
This overview covers 8 ZIP codes and 12 community water systems in Mariposa County. It also stands in for 4 ZIP codes whose utility has too little EPA data for a page of its own.
System population figures are summed from EPA registry records and can overlap where wholesalers and retail systems serve the same people. They are not a Census county-population estimate.
Water systems with the most complete records
| Water system | People served | PFAS survey results | PFAS found | Health-based violations | Lead, 9 in 10 homes at or below |
|---|---|---|---|---|---|
| Ponderosa Basin Mutual Wtr Co CA2210002 | 798 | 210 | 0 | 0 | 0 ppb |
| Mcclure Boat Club, INC. CA2210905 | 286 | 0 | 0 | 1 | 10 ppb |
| Mariposa Pines Mutual CA2210906 | 284 | 0 | 0 | 1 | 0 ppb |
| Yosemite Terrace Estates CA2210925 | 130 | 0 | 0 | 1 | 6.6 ppb |
| Mariposa Public Utility Dist CA2210001 | 2,000 | 0 | 0 | 0 | 0 ppb |
| Yosemite Nps-Yosemite Valley CA2210503 | 1,000 | 0 | 0 | 0 | 0 ppb |
| Granite Whisper Creek R.V. Resort Ll. FL5224074 | 880 | 0 | 0 | 0 | 1.8 ppb |
| Cedar Lodge CA2210900 | 656 | 0 | 0 | 0 | 3.7 ppb |
| Yosemite Nps-El Portal CA2210515 | 635 | 0 | 0 | 0 | 0 ppb |
| Yosemite West Water System CA2210924 | 420 | 0 | 0 | 0 | 2.2 ppb |
| Mpwd-Coulterville Csa 1 CA2210901 | 193 | 0 | 0 | 0 | 1.4 ppb |
| Yosemite Nps-Wawona CA2210510 | 150 | 0 | 0 | 0 | 0 ppb |
ZIP reports in Mariposa County
No ZIP report in this county is published yet.
These ZIP codes are covered by this overview because their utility has too little EPA data for a separate page: 93623, 95306, 95325, 95345.
Sources and scope
EPA UCMR 5 occurrence data, samples collected 2023-01-03 – 2026-06-17, final release, August 2026 (file dated Aug 28, 2026); EPA SDWIS via ECHO, 2026Q2 extract (file dated Jul 9, 2026); EPA service-area boundaries v3.0; Census 2020 ZCTAs. Page generated 2026-09-03.
Counts cover the systems that report this county to EPA. A water system may cross county lines. "Found" means at least one result at or above the laboratory reporting level; it is not a compliance finding.