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Public water system record

City of Stockton

Serves Stockton, San Joaquin County, CA · 191,302 people served

Federal records show 2 health-based violations and 2 monitoring/reporting issues for City of Stockton in the last ten years. The most serious issue in this window was a resolved Total Trihalomethanes (TTHMs) violation.

  • CA3910012
  • STOCKTON
  • CA
  • 191,302 served

System profile

Source water Surface water
ZIP 95206
EPA system ID CA3910012

Verify this system on EPA ECHO →

Health-based violations, last 10 years
2
Resolved
2
Unresolved
0
Any acute record
No
Monitoring issues, last 10 years
2

Key facts

  • City of Stockton draws water from 16 wells and 2 surface water intakes (4 of them for emergency, seasonal or other part-time use).
  • Highest measured level in the last 10 years: Total Trihalomethanes (TTHMs), 0.083 mg/L, federal limit 0.08 mg/L (at or just above the limit), 2023.
  • Most recent formal enforcement: compliance order (no penalty) by California, March 2025.
  • Record on file since 1999, with 3 health-based violations before October 19, 2016.

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Health-based violations

Since October 2016

Violation data reflects EPA records through March 2026. For the most current status, visit the EPA ECHO database.

Contaminant Rule family Start date Status Acute
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.083 mg/L, federal limit 0.08 mg/L (at or just above the limit)
 220 Apr 1, 2023 Resolved No
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.081 mg/L, federal limit 0.08 mg/L (at or just above the limit)
 220 Jan 1, 2023 Resolved No

Monitoring and reporting issues

Since October 2016

Missed tests or reports, not contaminants found above a limit.

Issue Start date Status
Nitrate
Monitoring and reporting
 Jan 1, 2024 Resolved
Lead and Copper Rule
Monitoring and reporting
 Oct 1, 2021 Resolved

Full record since 1999

EPA's records for City of Stockton go back to 1999. Before October 19, 2016 they list 3 health-based violations (3 resolved) and 2 monitoring or reporting violations.

Violations that began in Health-based Monitoring and reporting
1990s 1 0
2000s 0 2
2010 to October 18, 2016 2 0
2020s 2 2

Most recent health-based violation before October 19, 2016: Surface Water Treatment Rule, began March 2016, Resolved.

Show all 3 health-based violations before October 19, 2016
Contaminant Start date Status
Surface Water Treatment Rule
Treatment technique failure
 Mar 1, 2016 Resolved
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.096 mg/L, federal limit 0.08 mg/L (1.2 times the limit)
 Jan 1, 2013 Resolved
Total Coliform
Contaminant limit exceeded
 Dec 1, 1999 Resolved

Enforcement actions

California regulators took 8 formal enforcement actions against City of Stockton between 2000 and 2025. The most recent was a compliance order (no penalty) in March 2025.

Date By Action Violations covered
Mar 4, 2025 California Compliance order (no penalty) 1 violation: Nitrate
Oct 19, 2023 California Compliance order (no penalty) 1 violation: Lead and Copper Rule
Apr 27, 2023 California Compliance order (no penalty) 2 violations (2 health-based): Total Trihalomethanes (TTHMs)
Apr 14, 2016 California Compliance order (no penalty) 1 violation (1 health-based): Surface Water Treatment Rule
Mar 7, 2013 California Compliance order (no penalty) 1 violation (1 health-based): Total Trihalomethanes (TTHMs)
Dec 14, 2005 California Compliance order (no penalty) 1 violation: Total Coliform
Nov 21, 2001 California Compliance order (no penalty) 1 violation: Consumer Confidence Rule
Jan 27, 2000 California Compliance order (no penalty) 1 violation (1 health-based): Total Coliform

What the violations mean

Total Trihalomethanes (TTHMs)

2 incidents

Disinfection byproduct levels exceeded the federal limit

Long-term TTHM exposure may increase bladder cancer risk

Where the water comes from

City of Stockton draws water from 16 wells and 2 surface water intakes (4 of them for emergency, seasonal or other part-time use). It also buys water from Stockton East Water District. 1 other community water system buys water from City of Stockton.

Buys water from

Community systems that buy water from it

Annual water quality report

City of Stockton must give its customers an annual water quality report (Consumer Confidence Report) by July 1, with the levels its tests found in the previous year.

Systems serving 10,000 or more people must mail or deliver the report to every customer, and from 2027 they must send it twice a year.

Find a posted report with EPA's Consumer Confidence Report search

Testing your own water

To test the water at your tap, or a private well this record does not cover, use a laboratory certified for drinking water by California.

Certified drinking water labs by state EPA guidance for private wells