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Community Water System · PWS CA3400138

Locke Water Works Co [Sws]

Walnut Grove, California 95690 - drinking water served from groundwater sources to 80 people, tracked in EPA SDWIS and UCMR5.

80
People served
104
EPA violations
87
Health-based
Untested
UCMR5 result

The verdict

EPA records 104 drinking-water violations at Locke Water Works Co [Sws], 84% of them health-based - above the California per-system average.

104
Total EPA violations on record
84%
Health-based (MCL / treatment failure)
80
People served by this system
N/A
PFAS compounds detected (UCMR5)

Water Quality Snapshot: Locke Water Works Co [Sws]

Locke Water Works Co [Sws] is a private-owned community water system that delivers drinking water to 80 residents in Walnut Grove, California (Sacramento County) through 44 service connections. Its water is drawn from groundwater sources. EPA's Safe Drinking Water Information System records 104 total violations for this system , of which 87 (84%) are health-based, meaning a contaminant exceeded an EPA Maximum Contaminant Level or a required treatment technique failed. A further 6 monitoring and reporting violations are on file. The most recent violation on record dates to 2024.

The most frequently cited contaminant at this system is Arsenic, recorded in 71 violations (MCL, health-based). This system has not yet been sampled under EPA's UCMR5 PFAS monitoring program, so no PFAS detection data is available here.

Across California, EPA tracks 7,249 public water systems serving 42,404,883 people, with 153,308 cumulative violations and 63,983 health-based violations on record. About 89% of systems in the state carry at least one violation, and state-wide the average per system is 21.1 violations. Statewide, 231 of 694 UCMR5-tested systems have reported PFAS detections (33.3%).

Locke Water Works Co [Sws]'s 104 violations sit above the California average.

All figures above are sourced directly from EPA SDWIS and UCMR5 public data releases and are updated as EPA publishes new reporting cycles.

Population Served
80
Total Violations
104
Health-Based Violations
87
Water Source
Groundwater

System Details

System Type
Community
Owner Type
Private
Connections
44
County
Sacramento
School/Daycare
No
MCL Violations
87
Monitoring Violations
6
Treatment Tech Violations
0

Violation History

Contaminant violations recorded by EPA.

Contaminant Category Count Latest
Arsenic MCL 71 2021
Coliform (TCR) MCL 16 2001
Consumer Confidence Rule Other 8 2015
Lead and Copper Rule MR 3 2024
Gross Alpha, Excl. Radon and U MR 2 1981
Nitrite MR 1 2005

Verify This Water System

The figures above are aggregated from EPA's public databases. To verify the underlying records, or to file a complaint, request a Consumer Confidence Report, or check current monitoring status, go directly to the federal and state regulators that enforce the Safe Drinking Water Act for Locke Water Works Co [Sws].

Federal Source of Truth

EPA SDWIS, Federal Reports

EPA's Safe Drinking Water Information System (SDWIS) holds the federal compliance record for every regulated public water system. Open the system-level report by PWS ID:

View PWS ID CA3400138 on SDWIS

Source: EPA SDWIS Federal Reports Search

State Regulator

California Drinking Water Authority

California State Water Resources Control Board, Division of Drinking Water is the primacy agency that licenses and inspects Locke Water Works Co [Sws] under EPA-delegated authority.

Open CA regulator portal

Source: California State Water Resources Control Board, Division of Drinking Water

Violation Timeline

Each row links to the EPA SDWIS public record for verification. Cross-reference the contaminant code on EPA's federal report to see violation dates, return-to-compliance status, and enforcement actions.

Year (latest) Contaminant Category Count EPA Record
2024 Lead and Copper Rule MR 3 SDWIS / CA3400138 / 5000
2021 Arsenic MCL 71 SDWIS / CA3400138 / 1005
2015 Consumer Confidence Rule Other 8 SDWIS / CA3400138 / 7000
2005 Nitrite MR 1 SDWIS / CA3400138 / 1041
2001 Coliform (TCR) MCL 16 SDWIS / CA3400138 / 3100
1981 Gross Alpha, Excl. Radon and U MR 2 SDWIS / CA3400138 / 4000

How Locke Water Works Co [Sws] Compares

Cross-reference this system's record against state averages and the federal MCL framework for context.

Metric Locke Water Works Co [Sws] California avg Federal benchmark
Total violations 104 21.1 SDWA compliance, any non-zero count is a recorded breach
Health-based violations 87 8.8 Indicates a contaminant exceeded a federal MCL
PFAS detection None 33.3% EPA final rule (2024): PFOA/PFOS MCL = 4.0 ppt
Population served 80 5,850 Sizing context for compliance burden

Sources: EPA SDWIS and EPA National Primary Drinking Water Regulations (40 CFR Part 141). State averages computed across 7,249 regulated public water systems in California.

Federal MCL reference, Safe Drinking Water Act thresholds ▼
Contaminant Federal MCL / Action Level Note
Lead 0 mg/L (Action Level: 0.015 mg/L) Lead and Copper Rule treatment technique
Arsenic 0.010 mg/L (10 ppb) Health-based MCL since 2006
Total Coliform Treatment technique (RTCR) Indicator organism, monitoring trigger
PFOA / PFOS (PFAS) 4.0 ppt each (final 2024 rule) Compliance deadline 2029 (EPA proposed extending to 2031, not yet final as of May 2026)
Nitrate (as N) 10 mg/L Acute health risk for infants

Frequently Asked Questions

Is Locke Water Works Co [Sws] water safe to drink? ▼
Locke Water Works Co [Sws] (PWS ID: CA3400138) has 104 recorded violations in the EPA SDWIS database. No PFAS contamination was detected in UCMR5 testing. This system serves 80 people using Groundwater sources.
How many people does Locke Water Works Co [Sws] serve? ▼
Locke Water Works Co [Sws] serves 80 people in Walnut Grove, California. It is a Private-owned system using Groundwater water sources with 44 service connections.
What type of violations does Locke Water Works Co [Sws] have? ▼
Locke Water Works Co [Sws] has 104 total violations: 87 health-based violations (MCL exceedances or treatment failures), 6 monitoring/reporting violations, and 0 treatment technique violations. Health-based violations indicate contaminant levels exceeded EPA safe limits.
Has PFAS been detected in Locke Water Works Co [Sws] water? ▼
No PFAS testing data is available for Locke Water Works Co [Sws] under the EPA's UCMR5 monitoring program.
What water source does Locke Water Works Co [Sws] use? ▼
Locke Water Works Co [Sws] uses Groundwater as its primary water source. It is classified as a Community Water System (CWS), serving residential populations year-round.
Where does this data come from? ▼
All data comes from the EPA Safe Drinking Water Information System (SDWIS) and the UCMR5 PFAS monitoring program. SDWIS tracks compliance for all public water systems regulated under the Safe Drinking Water Act.
Data Sources: EPA Safe Drinking Water Information System (SDWIS), Q4 2025. This data is provided for informational purposes only.

Read our methodology - 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 Editorial

Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. This system's figures are rendered directly from 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.