Public water system · CA3901354
ActiveLarsen Ranch 39-40/Water System
At a glance
Larsen Ranch 39-40/Water System (PWSID CA3901354) is an active non-transient non-community water system in San Joaquin County, California. It reports serving 30 people through 11 service connections. Its primary water source is groundwater, and EPA lists it as privately owned. Of the 12 most recent violations in EPA's records, one is health-based, and the most recent began in July 2025.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
30
Service connections
11
Primary source
GW
Groundwater
System type
NTNCWS
Non-transient non-community water system
System record
How does Larsen Ranch 39-40/Water System compare with other water systems in San Joaquin County?
By EPA's size categories, Larsen Ranch 39-40/Water System is a very small system (500 people or fewer). San Joaquin County has 302 active public water systems. Its population served is well below the county average of 2,571 people per system, and accounts for less than 0.1% of the 776,334 people reported by systems filed under the county. Across California, the 7,479 active systems average 5,706 people each. Nationally, the average active non-transient non-community water system reports serving 430 people, so Larsen Ranch 39-40/Water System is well below that figure.
What does “non-transient non-community water system” mean?
A non-transient non-community water system regularly serves at least 25 of the same people for more than six months a year, but not where they live. Schools, factories, office buildings and hospitals with their own supply are typical examples. California has 1,466 active non-transient non-community water systems, 20% of the state's 7,479 active systems. Groundwater means the system draws its water from wells or springs fed by underground aquifers. 6,179 California systems (83%) list groundwater as their primary source.
Who owns and regulates Larsen Ranch 39-40/Water System?
EPA lists Larsen Ranch 39-40/Water System as privately owned. The CA state drinking water program is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act. 225 of the 302 active systems in San Joaquin County (75%) are also privately owned.
Does Larsen Ranch 39-40/Water System have drinking water violations?
Of the 12 most recent violations in EPA's records, one is health-based, and the most recent began in July 2025. The violations listed here began between July 2022 and July 2025. By type: 7 monitoring, 2 public notice, recordkeeping or other, 1 required treatment not met, 1 reporting and 1 monitoring and reporting. The contaminant or rule involved most often is Revised Total Coliform Rule (7 of them). EPA lists 6 as resolved, 3 as addressed, 2 as unaddressed and 1 as archived. Resolved means at least one resolving action is on record: the system returned to compliance, the rule no longer applies, or no further action was needed. Addressed means the violation is not resolved or archived and is covered by formal enforcement. Unaddressed means the violation is not resolved or archived and is not yet covered by formal enforcement. Archived means the violation was not marked resolved but is more than five years past the end of the noncompliance period, so it no longer counts toward current compliance status.
| Began | Violation | Contaminant or rule | Health-based | Status |
|---|---|---|---|---|
| 2025-07-01 | Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71 | Consumer Confidence Rulecode 7000 | No | Addressed |
| 2024-10-17 | Required treatment not metLSL Inventory · code 2E | Lead and Copper Rule Revisionscode 5200 | Yes | Unaddressed |
| 2024-10-17 | ReportingLSL Reporting · code 4G | Lead and Copper Rule Revisionscode 5200 | No | Unaddressed |
| 2024-03-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Archived |
| 2023-02-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2023-01-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2022-12-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2022-11-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2022-10-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2022-10-01 | Monitoring and reportingFollow-up Or Routine LCR Tap M/R · code 52 | Lead and Copper Rulecode 5000 | No | Addressed |
| 2022-07-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2022-07-01 | Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71 | Consumer Confidence Rulecode 7000 | No | Addressed |
The 12 most recent violations in EPA's records, newest first.Labels and codes come from EPA's SDWIS reference tables. A monitoring or reporting violation means a required test or report was missed or late; it does not by itself mean a contaminant was found. "Health-based" marks violations of a legal limit or required treatment.
Larsen Ranch 39-40/Water System: frequently asked questions
Who runs Larsen Ranch 39-40/Water System?
Larsen Ranch 39-40/Water System (PWSID CA3901354) is a non-transient non-community water system privately owned. It is regulated by the CA state drinking water program.
How many people does Larsen Ranch 39-40/Water System serve?
Larsen Ranch 39-40/Water System reports serving 30 people through 11 service connections in San Joaquin County, California.
Where does Larsen Ranch 39-40/Water System get its water?
EPA SDWIS lists this system's primary water source as groundwater. Groundwater means the system draws its water from wells or springs fed by underground aquifers.
Does Larsen Ranch 39-40/Water System have any drinking water violations?
Of the 12 most recent violations in EPA's records, one is health-based, and the most recent began in July 2025. A monitoring or reporting violation means a required test or report was missed or late; it does not by itself mean a contaminant was found.
Is Larsen Ranch 39-40/Water System's water safe to drink?
AquaCensus shows EPA compliance records, not current water test results, so it cannot say whether the water is safe at a given moment. Of the 12 most recent violations in EPA's records, one is health-based, and the most recent began in July 2025. For current results, consult EPA ECHO, or the CA state drinking water program.
Where can I find Larsen Ranch 39-40/Water System's water quality report?
The annual Consumer Confidence Report requirement applies to community water systems. Larsen Ranch 39-40/Water System is a non-transient non-community water system, so it is not required to publish one; like every public water system, it must notify the people it serves about violations under EPA's public notification rules.
Other water systems in San Joaquin County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| City of Stockton | San Joaquin | 191,302 | Community | Surface water |
| California Water Service - Stockton | San Joaquin | 176,266 | Community | Purchased surface water |
| Tracy, City of | San Joaquin | 96,609 | Community | Surface water |
| Manteca, City of | San Joaquin | 84,928 | Community | Purchased surface water |
| Lodi, City of | San Joaquin | 68,272 | Community | Surface water |
| City of Lathrop | San Joaquin | 35,080 | Community | Purchased surface water |
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About this data
Source: U.S. EPA Safe Drinking Water Information System (SDWIS) and SDWA violation records, via EPA ECHO, as published October 1, 2026 — AquaCensus refreshes it quarterly. See the methodology for how records are matched, cleaned and scored.
Cite as: AquaCensus, “Larsen Ranch 39-40/Water System, PWSID CA3901354, California”, https://aquacensus.com/water-systems/california/larsen-ranch-39-40-water-system-ca3901354 (data as of October 1, 2026).