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Counties → California

San Joaquin County, California

SDWIS compliance plate

Sheet CA077 · San Joaquin County 310 sys · 5,057 viol · #84/3254

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

  • VIOL-SEVERE 93.2% flagged
  • HEALTH-HIGH 58.9% health
  • RANK-TOP #84/3254
  • PHOTO-FINISH ±0.1 pp
  • PFAS-HIGH 53.8% detect
  • SRC-GW GW lead 95%
  • SYS-LARGE 310 systems
  • BOOK-FULL 7/7 fields

Nearest flagged-rate peer: Los Angeles County ( -0.1 pp flagged-rate)

According to EPA SDWIS county population served used on /counties, San Joaquin County ranks #84 of 3,254 counties by people served, and #14 of 58 counties in California. See methodology · corpus placement.

San Joaquin County standing, mid-flagged corpus third

Flagged-system rate 93.2% is in the corpus middle third (≤ 100.0% flagged) across 2,973 counties with ≥3 SDWIS systems . Health-based share 58.9% is health-based share above the upper third (> 24.5%) . UCMR5 detect rate 53.8% is UCMR5 detect rate above the tested-pool upper third (> 33.3%) . Population served ranks #84 of 3,254 · #14 of 58 in California.

Flagged-rate neighbourhood around San Joaquin County

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

0% 20% 40% 60% 80% 100% Alpine · lowest Los Angeles · near Humboldt · near Sutter · highest 70% 93% 93.1% 93.2% 93.4% 93.5% 97.1%

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

Water Systems

System Name Population Violations PFAS
City of Stockton 191,302 24 Detected
California Water Service - Stockton 176,266 2 Detected
Tracy, City Of 96,609 10 Clean
Manteca, City Of 84,928 77 Detected
Lodi, City Of 68,272 16 Detected
City of Lathrop 35,080 124 Detected
City of Mountain House 24,948 3 Clean
Ripon, City Of 15,741 30 Detected
Escalon, City Of 7,429 35 Clean
San Joaquin County - Lincoln Village 5,990 5 Clean
Cdcr California Health Care Facility 5,551 6 -
San Joaquin County-Mokelumne Acres 3,802 0 Detected
Lockeford Community Serv. Dist. 3,572 20 -
Jimmys One Stop 2,505 27 -
San Joaquin County - Colonial Heights 1,841 1 -
Linden County Water District 1,784 12 -
Little Potato Slough Mutual 1,510 29 -
Oakwood Lake Water District-Subdivision 1,479 12 -
Starbucks 1,200 0 -
Defense Distrib. Depot - Tracy Site 1,200 9 -
Fairoaks PWS #44 1,172 1 -
Family Market Water System 1,105 0 -
San Joaquin County-Raymus Village 1,086 12 -
Sjc Micke Grove Park 1,025 38 -
Escalon Golf Course WS 1,010 16 -
King Island Resort PWS 1,000 28 -
Smk Chevron 1,000 2 -
Jahant Food N Fuel Stop 1,000 12 -
Horizon Christian Fellowship 1,000 37 -
San Joaquin County - Thornton 964 7 -
St Marys High School 950 11 -
San Joaquin County - Wilkinson Manor 851 8 -
Navarra Water System 730 26 -
Stockton Verde Mobile Home Park 711 20 -
Lodi Usd-Davis School 630 18 -
Rodeway Inn 600 7 -
San Joaquin River Club Inc 600 13 Clean
Central Valley Baptist Church WS 556 32 -
Harney Lane Migrant Center WS 500 66 -
Defense Distrib. Depot, Sharpe Site 500 15 -
Sutter Home Winery Inc. 463 4 -
Delicato Vineyards 430 39 -
Morada Estates N PWS #46 426 1 -
Lodi Usd-Houston School 405 11 -
Wienerschnitzel 400 0 -
Oak View Union Elementary Sch 350 23 -
Musco Family Olive Co 348 5 -
Arbor Mobile Home Park WS 340 26 -
Phillips Farms 330 56 -
French Camp Golf Course 327 37 -

Compare beyond California

Mid-flagged peers for San Joaquin County

Cross-state counties nearest San Joaquin County on flagged-system share (93.2%) and cumulative violation count (5,057). 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.