Public water system · CA5602407
ActiveRio Mesa High School/Oxnard Uhs
At a glance
Rio Mesa High School/Oxnard Uhs (PWSID CA5602407) is an active non-transient non-community water system in Ventura County, California. It reports serving 2,600 people through 13 service connections. Its primary water source is groundwater, and EPA lists it as owned by a local government. EPA's records list 4 violations for this system; 2 are health-based, and the most recent began in October 2024.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
2,600
Service connections
13
Primary source
GW
Groundwater
System type
NTNCWS
Non-transient non-community water system
System record
How does Rio Mesa High School/Oxnard Uhs compare with other water systems in Ventura County?
By EPA's size categories, Rio Mesa High School/Oxnard Uhs is a small system (501 to 3,300 people). Ventura County has 95 active public water systems. Its population served is well below the county average of 9,293 people per system, and accounts for 0.3% of the 882,799 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 Rio Mesa High School/Oxnard Uhs is about 6 times 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 Rio Mesa High School/Oxnard Uhs?
EPA lists Rio Mesa High School/Oxnard Uhs as owned by a local 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. 29 of the 95 active systems in Ventura County (31%) are also owned by a local government.
Does Rio Mesa High School/Oxnard Uhs have drinking water violations?
EPA's records list 4 violations for this system; 2 are health-based, and the most recent began in October 2024. The violations listed here began between May 1997 and October 2024. By type: 1 reporting, 1 required treatment not met, 1 monitoring and 1 contaminant level above the legal limit. The contaminant or rule involved most often is Lead and Copper Rule Revisions (2 of them). EPA lists 2 as unaddressed and 2 as resolved. Unaddressed means the violation is not resolved or archived and is not yet covered by formal enforcement. 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 |
|---|---|---|---|---|
| 2024-10-17 | ReportingLSL Reporting · code 4G | Lead and Copper Rule Revisionscode 5200 | No | Unaddressed |
| 2024-10-17 | Required treatment not metLSL Inventory · code 2E | Lead and Copper Rule Revisionscode 5200 | Yes | Unaddressed |
| 2022-09-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 1997-05-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
All 4 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.
Rio Mesa High School/Oxnard Uhs: frequently asked questions
Who runs Rio Mesa High School/Oxnard Uhs?
Rio Mesa High School/Oxnard Uhs (PWSID CA5602407) is a non-transient non-community water system owned by a local government. It is regulated by the CA state drinking water program.
How many people does Rio Mesa High School/Oxnard Uhs serve?
Rio Mesa High School/Oxnard Uhs reports serving 2,600 people through 13 service connections in Ventura County, California.
Where does Rio Mesa High School/Oxnard Uhs 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 Rio Mesa High School/Oxnard Uhs have any drinking water violations?
EPA's records list 4 violations for this system; 2 are health-based, and the most recent began in October 2024. 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 Rio Mesa High School/Oxnard Uhs' 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. EPA's records list 4 violations for this system; 2 are health-based, and the most recent began in October 2024. For current results, consult EPA ECHO, or the CA state drinking water program.
Where can I find Rio Mesa High School/Oxnard Uhs' water quality report?
The annual Consumer Confidence Report requirement applies to community water systems. Rio Mesa High School/Oxnard Uhs 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 Ventura County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Oxnard Water Dept | Ventura | 200,232 | Community | Purchased surface water |
| Ventura Water Department | Ventura | 113,500 | Community | Surface water |
| Ventura Wwd No. 8 - Simi Valley | Ventura | 94,738 | Community | Purchased surface water |
| Cal American Water Co | Ventura | 66,809 | Community | Purchased surface water |
| City of Thousand Oaks Water Department | Ventura | 53,157 | Community | Purchased surface water |
| Camarillo Water Dept | Ventura | 46,824 | 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, “Rio Mesa High School/Oxnard Uhs, PWSID CA5602407, California”, https://aquacensus.com/water-systems/california/rio-mesa-high-school-oxnard-uhs-ca5602407 (data as of October 1, 2026).