Public water system · CA4200539
ActiveRancho Oso
At a glance
Rancho Oso (PWSID CA4200539) is an active transient non-community water system in Santa Barbara County, California. It reports serving 416 people through 3 service connections. Its primary water source is groundwater, and EPA lists it as privately owned. EPA's records list 6 violations for this system; all are health-based, and the most recent began in September 2008.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
416
Service connections
3
Primary source
GW
Groundwater
System type
TNCWS
Transient non-community water system
System record
How does Rancho Oso compare with other water systems in Santa Barbara County?
By EPA's size categories, Rancho Oso is a very small system (500 people or fewer). Santa Barbara County has 150 active public water systems. Its population served is well below the county average of 3,255 people per system, and accounts for less than 0.1% of the 488,317 people reported by systems filed under the county. Across California, the 7,479 active systems average 5,706 people each. Nationally, the average active transient non-community water system reports serving 144 people, so Rancho Oso is about 189% above that figure.
What does “transient non-community water system” mean?
A transient non-community water system serves places where people do not stay long, such as gas stations and campgrounds, and regularly serves at least 25 people a day for at least 60 days a year. California has 3,016 active transient non-community water systems, 40% 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 Rancho Oso?
EPA lists Rancho Oso 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. 121 of the 150 active systems in Santa Barbara County (81%) are also privately owned.
Does Rancho Oso have drinking water violations?
EPA's records list 6 violations for this system; all are health-based, and the most recent began in September 2008. The violations listed here began between August 1996 and September 2008. By type: 6 contaminant level above the legal limit. The contaminant or rule involved most often is Total coliform bacteria (TCR) (6 of them). EPA lists 6 as resolved. 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 |
|---|---|---|---|---|
| 2008-09-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 1999-06-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 1997-08-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 1997-02-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 1996-09-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 1996-08-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
All 6 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.
Rancho Oso: frequently asked questions
Who runs Rancho Oso?
Rancho Oso (PWSID CA4200539) is a transient non-community water system privately owned. It is regulated by the CA state drinking water program.
How many people does Rancho Oso serve?
Rancho Oso reports serving 416 people through 3 service connections in Santa Barbara County, California.
Where does Rancho Oso 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 Rancho Oso have any drinking water violations?
EPA's records list 6 violations for this system; all are health-based, and the most recent began in September 2008. 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 Rancho Oso'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. EPA's records list 6 violations for this system; all are health-based, and the most recent began in September 2008. For current results, consult EPA ECHO, or the CA state drinking water program.
Where can I find Rancho Oso's water quality report?
The annual Consumer Confidence Report requirement applies to community water systems. Rancho Oso is a 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 Santa Barbara County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| City of Santa Maria Utilities Department | Santa Barbara | 109,477 | Community | Purchased surface water |
| City of Santa Barbara Water Department | Santa Barbara | 99,323 | Community | Surface water |
| Goleta Water District | Santa Barbara | 84,462 | Community | Surface water |
| Lompoc-City Water Utility Div | Santa Barbara | 40,473 | Community | Surface water |
| Golden State Water Company - Orcutt | Santa Barbara | 34,102 | Community | Purchased surface water |
| Carpinteria Valley Water District | Santa Barbara | 15,996 | 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, “Rancho Oso, PWSID CA4200539, California”, https://aquacensus.com/water-systems/california/rancho-oso-ca4200539 (data as of October 1, 2026).