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Counties → California

Mariposa County, California

SDWIS compliance plate

Sheet CA043 · Mariposa County 69 sys · 887 viol · #1531/3254

VIOL-SEVERE · HEALTH-MID · RANK-MID · PHOTO-FINISH · PFAS-CLEAN · SRC-GW · SYS-MID · BOOK-FULL

  • VIOL-SEVERE 88.4% flagged
  • HEALTH-MID 44.4% health
  • RANK-MID #1531/3254
  • PHOTO-FINISH ±0.3 pp
  • PFAS-CLEAN 0.0% detect
  • SRC-GW GW lead 87%
  • SYS-MID 69 systems
  • BOOK-FULL 7/7 fields

Nearest flagged-rate peer: Napa County ( -0.3 pp flagged-rate)

According to EPA SDWIS county population served used on /counties, Mariposa County ranks #1,531 of 3,254 counties by people served, and #53 of 58 counties in California. See methodology · corpus placement.

Mariposa County standing, lower-flagged corpus third

Flagged-system rate 88.4% is at or below the corpus lower third (≤ 92.7% flagged) across 2,973 counties with ≥3 SDWIS systems . Health-based share 44.4% is health-based share above the upper third (> 24.5%) . UCMR5 detect rate 0.0% is UCMR5 detect rate at or below the tested-pool lower third (≤ 0.0%) . Population served ranks #1,531 of 3,254 · #53 of 58 in California.

Flagged-rate neighbourhood around Mariposa County

Lowest/highest poles plus in-state counties nearest Mariposa County on % of SDWIS systems with ≥1 violation. Full ladder: /counties.

0% 20% 40% 60% 80% 100% Alpine · lowest Napa · near Siskiyou · near Sutter · highest 70% 88% 88.1% 88.4% 88.9% 88.9% 97.1%

Source: EPA SDWIS (county aggregates) As of 2026-05-15

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 -

Compare beyond California

Lower-flagged peers for Mariposa County

Cross-state counties nearest Mariposa County on flagged-system share (88.4%) and cumulative violation count (887). In-state neighbours stay on the compliance plate above.

Similar flagged-system rate

Nearest cross-state counties by % of SDWIS systems with at least one violation on record.

4 peers

Similar violation load

Nearest cross-state counties by cumulative SDWIS violation count (all systems in the county).

4 peers

Read our methodology · Check your water system - 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

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.