Transient Non-Community Water System · PWS CA4200539
Rancho Oso
Santa Barbara, California 93105 - drinking water served from surface water sources to 416 people, tracked in EPA SDWIS and UCMR5.
- 416
- People served
- 12
- EPA violations
- 12
- Health-based
- Untested
- UCMR5 result
The verdict
EPA records 12 drinking-water violations at Rancho Oso, 100% of them health-based - below the California per-system average.
- 12
- Total EPA violations on record
- 100%
- Health-based (MCL / treatment failure)
- 416
- People served by this system
- N/A
- PFAS compounds detected (UCMR5)
Water Quality Snapshot: Rancho Oso
Rancho Oso is a private-owned transient non-community water system that delivers drinking water to 416 residents in Santa Barbara, California (Santa Barbara County) through 3 service connections. Its water is drawn from surface water sources. EPA's Safe Drinking Water Information System records 12 total violations for this system , of which 12 (100%) are health-based, meaning a contaminant exceeded an EPA Maximum Contaminant Level or a required treatment technique failed. The most recent violation on record dates to 2008.
The most frequently cited contaminant at this system is Coliform (TCR), recorded in 12 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, 447 of 694 UCMR5-tested systems have reported PFAS detections (64.4%).
Rancho Oso's 12 violations sit below 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.
System Details
- System Type
- Transient Non-Community
- Owner Type
- Private
- Connections
- 3
- County
- Santa Barbara
- School/Daycare
- No
- MCL Violations
- 12
- Monitoring Violations
- 0
- Treatment Tech Violations
- 0
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| Coliform (TCR) | MCL | 12 | 2008 |
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 Rancho Oso.
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 CA4200539 on SDWISSource: EPA SDWIS Federal Reports Search
California Drinking Water Authority
California State Water Resources Control Board, Division of Drinking Water is the primacy agency that licenses and inspects Rancho Oso under EPA-delegated authority.
Open CA regulator portalSource: 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 |
|---|---|---|---|---|
| 2008 | Coliform (TCR) | MCL | 12 | SDWIS / CA4200539 / 3100 |
How Rancho Oso Compares
Cross-reference this system's record against state averages and the federal MCL framework for context.
| Metric | Rancho Oso | California avg | Federal benchmark |
|---|---|---|---|
| Total violations | 12 | 21.1 | SDWA compliance, any non-zero count is a recorded breach |
| Health-based violations | 12 | 8.8 | Indicates a contaminant exceeded a federal MCL |
| PFAS detection | None | 64.4% | EPA final rule (2024): PFOA/PFOS MCL = 4.0 ppt |
| Population served | 416 | 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 Rancho Oso water safe to drink? ▼
How many people does Rancho Oso serve? ▼
What type of violations does Rancho Oso have? ▼
Has PFAS been detected in Rancho Oso water? ▼
What water source does Rancho Oso use? ▼
Where does this data come from? ▼
Read our methodology - how this data is sourced, computed, and verified.
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.