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Counties → California

Tuolumne County, California

SDWIS compliance plate

Sheet CA109 · Tuolumne County 120 sys · 1,665 viol · #666/3254

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

  • VIOL-SEVERE 92.5% flagged
  • HEALTH-MID 23.0% health
  • RANK-UPPER #666/3254
  • PHOTO-FINISH ±0.1 pp
  • PFAS-MID 40.0% detect
  • SRC-GW GW lead 76%
  • SYS-LARGE 120 systems
  • BOOK-FULL 7/7 fields

Nearest flagged-rate peer: Kern County ( -0.1 pp flagged-rate)

According to EPA SDWIS county population served used on /counties, Tuolumne County ranks #666 of 3,254 counties by people served, and #41 of 58 counties in California. See methodology · corpus placement.

Tuolumne County standing, lower-flagged corpus third

Flagged-system rate 92.5% is at or below the corpus lower third (≤ 92.7% flagged) across 2,973 counties with ≥3 SDWIS systems . Health-based share 23.0% is health-based share in the middle third (≤ 24.5%) . UCMR5 detect rate 40.0% is UCMR5 detect rate above the tested-pool upper third (> 33.3%) . Population served ranks #666 of 3,254 · #41 of 58 in California.

Flagged-rate neighbourhood around Tuolumne County

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

0% 20% 40% 60% 80% 100% Alpine · lowest Kern · near Fresno · near Sutter · highest 70% 92.2% 92.4% 92.5% 92.6% 93% 97.1%

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

Water Systems

System Name Population Violations PFAS
Tud - Upper Basin Water System 13,280 2 Clean
Tud - Sonora/Jamestown Water System 11,054 14 Clean
Tud - Columbia Water System 5,463 2 Clean
Peppery Bar and Grill, The 4,500 4 -
Cdcr - Sierra Conservation Center 3,571 30 -
Groveland Community Serv Dist 3,400 18 Detected
Lake Don Pedro Csd 3,240 58 -
Yosemite Nps-Tuolumne Meadows 2,500 5 -
Twain Harte Community Services District 2,378 5 -
MI Wuk Village Mut Wtr Co 2,163 11 -
Cold Springs Water Co 1,771 3 -
Tud - Ponderosa 1,767 23 -
Tud - Tuolumne Water System 1,761 3 -
Pinecrest Permittees Assn 1,298 10 -
Del Oro Water Company - Strawberry Div. 1,295 50 -
Phoenix Lake Estates Cc MWC 1,168 47 -
Sonora Water Resources, Inc 1,154 5 -
Sonora Meadows Mutual Wtr Co 1,123 11 -
Don Pedro Rec Ag:flem.meadows 1,041 28 -
Usbr-Tuttletown Rec Area 1,000 6 -
Tud-Apple Valley Estates 826 4 -
Usfs Clark Fork Campd 612 1 -
Jenness Park Christian Camp 507 8 -
Camp Tawonga 505 1 -
Camp Mather 500 8 -
Belleview Oaks Mutual Water Co 468 6 -
MI Wuk Heights MWC 445 15 -
Slide Inn Snowbowl Water Co 417 10 -
Yosemite Lakes Campground 413 36 -
Sierra Park Water Company Inc. 400 16 -
Berkeley Tuolumne Camp 380 30 -
Usfs Baker/Deadman Cgd 366 2 -
Sierra Village Mutual Water Co 361 12 -
Usfs Fraser Flat Campgd 348 10 -
Leisure Pines Mutual Water Co 340 10 -
Dodge Ridge Ski Resort 328 7 -
Cascade Estates 316 24 -
Heavenly Hills Christian Camp 304 10 -
Usfs Sourgrass Campgd 300 4 -
Yosemite Nps-White Wolf 300 0 -
Don Pedro Rec Ag:blue Oaks 296 2 -
Sierra Outdoor School 289 30 -
Bluebell Valley MWC 282 20 -
Peppermint Creek MHP 280 27 -
Rawhide Mutual Water Company 269 11 -
Christian Berets Conf. Center 268 6 -
Sonora Estates Mobile Home Park 235 7 -
Foothill Horizons 230 24 -
San Jose Family Camp 230 12 -
Under Canvas-Yosemite 226 0 -

Compare beyond California

Lower-flagged peers for Tuolumne County

Cross-state counties nearest Tuolumne County on flagged-system share (92.5%) and cumulative violation count (1,665). 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.