PlainWater
Counties → California

Mariposa County, California

Water Systems
69
Population Served
25,617
Total Violations
887
394 health-based
PFAS Detected
1
of 1 tested

Violation Analysis

88.4%
Systems with Violations
12.9
Avg Violations per System
44.4%
Health-Based Violations

Water Source Types

GW
41 systems (59%)
SW
9 systems (13%)

PFAS Contamination

1
Systems Tested
1
PFAS Detected
100.0%
Detection Rate

PFAS (per- and polyfluoroalkyl substances) are persistent chemicals found in drinking water. The EPA has set enforceable limits for several PFAS compounds under UCMR5 monitoring.

Compliance Snapshot

Mariposa California water systems by violation status, EPA SDWIS records.

No violations on record (7) One or more violations (43)

Violation history is cumulative, many flagged systems have already returned to compliance. Detail pages show per-system context.

Water Systems

System Name Population Violations PFAS
Yosemite Nps-Glacier Point 4,000 5 -
Blm-Briceburg Water System 3,196 8 -
Mariposa Public Utility Dist 2,000 184 -
Yosemite Nps-Bridalveil Fall 1,163 0 -
Mid - Mc Swain Rec Area 1,119 12 -
Yosemite Nps-Yosemite Valley 1,000 7 -
Yosemite Nps-Badger Pass 1,000 0 -
Delaware North Parks Services at Tenaya 800 24 -
Ponderosa Basin Mutual Wtr Co 798 30 Clean
Yosemite View Lodge 750 15 -
Cedar Lodge Resort 656 77 -
Yosemite Nps-El Portal 635 17 -
Yosemite Nps-Crane Flat 500 2 -
Mid - Mc Clure Point Rec Area 470 8 -
Musd - Woodland Elementary School 466 4 -
Yosemite Nps-Bridalveil Creek Cg 450 0 -
Yosemite West Water System 420 28 -
Mid - Barrett Cove 407 6 -
Yosemite Nps-May Lake Camp 300 0 -
Autocamp-Yosemite 290 8 -
McClure Boat Club, Inc. 286 10 -
Mariposa Pines Mutual 284 22 -
The Cottages at Tenaya Lodge 265 8 -
McPr-Cathey S Valley Park 250 12 -
Fishcamp Mutual Water Company 239 6 -
Camp Wawona 222 4 -
Mariposa District Fairground 200 2 -
Yosemite Nps-Arch Rock 200 2 -
New Life Christian Fellowship 200 6 -
Mpwd-Coulterville CSA 1 193 23 -
Summerdale Campground 175 2 -
Musd - Sierra Foothill Charter School 157 10 -
Yosemite Nps-Sunrise HI 150 2 -
Yosemite Nps-Wawona 150 17 -
Mid -Horseshoe Bend Rec Area 142 6 -
Musd - Mariposa Junior High School 134 6 -
Yosemite Terrace Estates 130 20 -
Yosemite Bug Hostel 122 12 -
Green Meadows Outdoor School 113 2 -
Wildhaven Yosemite Water System 100 0 -
Redwoods Main Water System 93 0 -
Mid - Bagby Recreation Area 85 8 -
North Wawona Estates (B System) 81 8 -
White Chief Mountain Lodge 73 6 -
Lds Church Mariposa 65 6 -
Yosemite's Scenic Wonders 65 0 -
Wampum Hill Trailer Village 62 1 -
Cdf & Fp - Mt. Bullion 60 12 -
Yosemite Ridge Resort 60 35 -
Mariposa Industrial Park Water Company 60 19 -

Other Counties in California

Los Angeles County
276 systems · 10,109,089 served · 3,972 violations
San Diego County
197 systems · 3,744,323 served · 4,832 violations
Orange County
46 systems · 3,201,893 served · 507 violations
Riverside County
201 systems · 2,839,125 served · 6,103 violations
San Bernardino County
318 systems · 2,830,626 served · 4,611 violations
Alameda County
27 systems · 2,249,634 served · 275 violations

Drinking Water Guides

Frequently Asked Questions

How many water violations are in Mariposa County? ▼
Mariposa County has 887 total drinking water violations across 69 water systems, of which 394 are health-based violations. 88.4% of systems have at least one violation.
How many people get water from Mariposa County systems? ▼
Water systems in Mariposa County serve approximately 25,617 people through 69 public water systems.
Has PFAS been detected in Mariposa County water? ▼
Of 1 water systems tested for PFAS in Mariposa County, 1 had PFAS detected (100.0% detection rate).
What types of water sources supply Mariposa County? ▼
Water systems in Mariposa County use GW (41 systems), SW (9 systems) as their primary water sources.
Are health-based violations serious? ▼
Health-based violations indicate that drinking water exceeded Maximum Contaminant Levels (MCLs) set by the EPA or failed treatment technique requirements. 44.4% of Mariposa County's violations are health-based. Not all violations indicate immediate health risk, but they require corrective action.
Data Sources & Methodology

Drinking water violation data from the EPA Safe Drinking Water Information System (SDWIS). PFAS testing data from the UCMR5 monitoring program. SDWIS tracks all public water systems regulated under the Safe Drinking Water Act.

Violations are categorized as health-based (Maximum Contaminant Level exceedances, treatment technique failures) or monitoring/reporting violations. Not all violations indicate an immediate health risk.

Read our methodology - how this data is sourced, computed, and verified.

Data sourced from EPA SDWIS and UCMR5 PFAS monitoring data. See our methodology for details. Retrieved and formatted by PlainWater Editorial

Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. This page draws directly on EPA SDWIS data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.