Water quality in Yosemite Valley, California
Yosemite Valley is in Mariposa County. 68 active public water systems serve the county; 19 had an EPA violation in the past three years.
Most likely your provider
Your location is within the outer bounds of this system's EPA service area.
Other community water systems in Mariposa County
10 systems, nearest first| System | Serves | Status | Rules violated, 3 yr | Distance |
|---|---|---|---|---|
| Yosemite Nps-El Portal |
635 | 0 | 9.2 mi | |
| Yosemite West Water System |
420 | 1 | 10.1 mi | |
| Yosemite Nps-Wawona |
150 | 1 | 14.8 mi | |
| Cedar Lodge |
28 | 1 | 16.0 mi | |
| Mariposa Pines Mutual |
294 | 2 | 18.4 mi | |
| Ponderosa Basin Mutual Wtr CO |
798 | 1 | 21.0 mi | |
| Mariposa Public Utility Dist |
2,000 | 0 | 27.7 mi | |
| Yosemite Terrace Estates |
130 | 2 | 29.9 mi | |
| Mpwd-Coulterville Csa 1 |
193 | 0 | 33.9 mi | |
| McClure Boat Club, Inc. |
36 | 0 | 39.1 mi |
Non-community systems in Mariposa County (57: schools, campgrounds, workplaces, restaurants)
These systems serve places you visit rather than homes.
About this data
Water systems are matched to Mariposa County, nearest to Yosemite Valley first. Your exact provider depends on your address and connection; the largest community water system in a county is usually the city or town utility. Distances are measured to the centre of the service area EPA publishes for the system.
Town locations and ZIP code areas come from U.S. Census Bureau 2020 files.
Source: the U.S. EPA's Enforcement and Compliance History Online system (ECHO), which publishes the federal Safe Drinking Water Information System. EPA's terms and values are shown as published. The California records are from EPA's data refresh of Oct 7, 2026; EPA refreshes this data quarterly, and states report to EPA with a lag of three to six months, so the newest violations may not appear yet. Retrieved from ECHO on Oct 11, 2026.