Public water system · CA3710707
ActiveUsn San Clemente Island
At a glance
Usn San Clemente Island (PWSID CA3710707) is an active non-transient non-community water system in San Diego County, California. It reports serving 800 people through 221 service connections. Its primary water source is purchased surface water, and EPA lists it as owned by the federal government. Of the 12 most recent violations in EPA's records, 10 are health-based, and the most recent began in June 2025.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
800
Service connections
221
Primary source
SWP
Purchased surface water
System type
NTNCWS
Non-transient non-community water system
System record
How does Usn San Clemente Island compare with other water systems in San Diego County?
By EPA's size categories, Usn San Clemente Island is a small system (501 to 3,300 people). San Diego County has 191 active public water systems. Its population served is well below the county average of 19,427 people per system, and accounts for less than 0.1% of the 3,710,459 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 Usn San Clemente Island is about 86% above 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. Purchased surface water means the system buys surface water from another public water system rather than drawing its own. 506 California systems (6.8%) list purchased surface water as their primary source.
Who owns and regulates Usn San Clemente Island?
EPA lists Usn San Clemente Island as owned by the federal government. 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. 16 of the 191 active systems in San Diego County (8.4%) are also owned by the federal government.
Does Usn San Clemente Island have drinking water violations?
Of the 12 most recent violations in EPA's records, 10 are health-based, and the most recent began in June 2025. The violations listed here began between October 2013 and June 2025. By type: 6 contaminant level above the legal limit, 4 required treatment not met and 2 monitoring. The contaminant or rule involved most often is Surface Water Treatment Rule (4 of them). EPA lists 10 as archived and 2 as resolved. 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. 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.
| Began | Violation | Contaminant or rule | Health-based | Status |
|---|---|---|---|---|
| 2025-06-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Archived |
| 2025-03-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Archived |
| 2025-02-01 | Required treatment not metTreatment Technique (SWTR and GWR) · code 41 | Surface Water Treatment Rulecode 0200 | Yes | Archived |
| 2025-01-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Haloacetic acids (HAA5)code 2456 | Yes | Archived |
| 2024-11-01 | Required treatment not metTreatment Technique (SWTR and GWR) · code 41 | Surface Water Treatment Rulecode 0200 | Yes | Archived |
| 2024-10-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Haloacetic acids (HAA5)code 2456 | Yes | Archived |
| 2024-09-01 | Required treatment not metTreatment Technique (SWTR and GWR) · code 41 | Surface Water Treatment Rulecode 0200 | Yes | Archived |
| 2024-07-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Haloacetic acids (HAA5)code 2456 | Yes | Archived |
| 2024-04-01 | Required treatment not metTreatment Technique (SWTR and GWR) · code 41 | Surface Water Treatment Rulecode 0200 | Yes | Archived |
| 2024-04-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Haloacetic acids (HAA5)code 2456 | Yes | Archived |
| 2014-01-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Total trihalomethanes (TTHM)code 2950 | Yes | Resolved |
| 2013-10-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Total trihalomethanes (TTHM)code 2950 | Yes | Resolved |
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.
Usn San Clemente Island: frequently asked questions
Who runs Usn San Clemente Island?
Usn San Clemente Island (PWSID CA3710707) is a non-transient non-community water system owned by the federal government. It is regulated by the CA state drinking water program.
How many people does Usn San Clemente Island serve?
Usn San Clemente Island reports serving 800 people through 221 service connections in San Diego County, California.
Where does Usn San Clemente Island get its water?
EPA SDWIS lists this system's primary water source as purchased surface water. Purchased surface water means the system buys surface water from another public water system rather than drawing its own.
Does Usn San Clemente Island have any drinking water violations?
Of the 12 most recent violations in EPA's records, 10 are health-based, and the most recent began in June 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 Usn San Clemente Island'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, 10 are health-based, and the most recent began in June 2025. For current results, consult EPA ECHO, or the CA state drinking water program.
Where can I find Usn San Clemente Island's water quality report?
The annual Consumer Confidence Report requirement applies to community water systems. Usn San Clemente Island 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 Diego County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| San Diego, City of | San Diego | 1,385,379 | Community | Surface water |
| Helix Water District | San Diego | 277,668 | Community | Surface water |
| Otay Water District | San Diego | 238,008 | Community | Purchased surface water |
| Sweetwater Authority | San Diego | 191,282 | Community | Surface water |
| Oceanside, City of | San Diego | 171,483 | Community | Purchased surface water |
| Escondido, City of | San Diego | 137,044 | Community | 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, “Usn San Clemente Island, PWSID CA3710707, California”, https://aquacensus.com/water-systems/california/usn-san-clemente-island-ca3710707 (data as of October 1, 2026).