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Counties → California

Stanislaus County, California

SDWIS compliance plate

Sheet CA099 · Stanislaus County 195 sys · 3,426 viol · #136/3254

VIOL-SEVERE · HEALTH-HIGH · RANK-TOP · PHOTO-FINISH · PFAS-LOW · SRC-GW · SYS-LARGE · BOOK-FULL

  • VIOL-SEVERE 90.3% flagged
  • HEALTH-HIGH 66.4% health
  • RANK-TOP #136/3254
  • PHOTO-FINISH ±0.2 pp
  • PFAS-LOW 13.3% detect
  • SRC-GW GW lead 95%
  • SYS-LARGE 195 systems
  • BOOK-FULL 7/7 fields

Nearest flagged-rate peer: San Benito County (+ 0.2 pp flagged-rate)

According to EPA SDWIS county population served used on /counties, Stanislaus County ranks #136 of 3,254 counties by people served, and #16 of 58 counties in California. See methodology · corpus placement.

Stanislaus County standing, lower-flagged corpus third

Flagged-system rate 90.3% is at or below the corpus lower third (≤ 92.7% flagged) across 2,973 counties with ≥3 SDWIS systems . Health-based share 66.4% is health-based share above the upper third (> 24.5%) . UCMR5 detect rate 13.3% is UCMR5 detect rate in the tested-pool middle third (≤ 33.3%) . Population served ranks #136 of 3,254 · #16 of 58 in California.

Flagged-rate neighbourhood around Stanislaus County

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

0% 20% 40% 60% 80% 100% Alpine · lowest Butte · near San Benito · near Sutter · highest 70% 89.1% 89.8% 90.3% 90.5% 91.4% 97.1%

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

Water Systems

System Name Population Violations PFAS
Modesto, City Of 218,771 25 Detected
Turlock, City Of 72,682 20 Clean
Ceres, City Of 54,513 28 Detected
Riverbank, City Of 24,834 34 Clean
Patterson, City Of 23,304 8 Clean
Oakdale, City Of 23,235 19 Clean
City of Modesto - Salida 14,537 25 Clean
City of Newman-Water Department 12,207 19 Clean
City of Waterford 8,788 7 Clean
Hughson, City Of 7,481 87 Clean
Keyes Community Services Dist. 5,672 122 Clean
Denair Community Services District 5,090 25 Clean
Joe's Travel Plaza (Eh) 5,026 18 Clean
Department of Transportation 4,375 17 -
Gregori High School 2,000 0 -
Western Hills Water District/Diablo Gran 2,000 87 -
Oid-Oakdale Rural Water System #1 1,570 3 -
City of Modesto - del Rio 1,327 7 -
City of Modesto - South Turlock 1,099 1 -
Waterford-River Pointe 1,079 0 -
Our Lady of Assumption Church 1,000 12 -
City of Modesto - Grayson 914 14 -
Hillsview Homes 887 25 -
Mesa Elementary School 860 0 -
Hart- Ransom Union School & District 650 30 -
Riverdale Park Tract Csd 610 23 -
Waterford - Hickman 597 4 -
Riverview Mobile Home Estates 540 32 -
Woodward Reservoir Water System 537 39 -
Crows Landing Comm Svc District 500 15 -
River Oak Grace-Water System 500 7 -
Jehovah's Witness Sierra Vista Cong 500 6 -
River Oaks/Kingdom Hall 500 3 -
Ceres Unified/Westport School 450 30 -
Bronco Winery 400 19 -
Stanislaus Union School Dist 390 20 -
Chatom School (Eh) 385 12 -
Sunrise Village MHP 353 15 -
5033 Pentecost 302 5 -
Nmip Fire & Water System, LLC 300 17 -
Covenant Grove Church 300 0 -
Oid #51 - Sunset Oaks #10 287 7 -
Oid #46 - Sunset Oaks 269 4 -
Park Heights Mutual Water Co 250 8 -
Ram Naam Mandali Church of Modesto 250 2 -
North Oaks Mutual Water Co 234 14 -
Paradise School 218 10 -
Casa de Amigos Manufactured Housing Comm 204 10 -
The Morning Star Company 200 25 -
Grizzly Rock Cafe 199 7 -

Compare beyond California

Lower-flagged peers for Stanislaus County

Cross-state counties nearest Stanislaus County on flagged-system share (90.3%) and cumulative violation count (3,426). 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.