Public water system · CA1710001
ActiveClearlake Oaks County Water District
At a glance
Clearlake Oaks County Water District (PWSID CA1710001) is an active community water system in Lake County, California. It reports serving 2,359 people through 2,161 service connections. Its primary water source is surface water, and EPA lists it as owned by a local government. EPA's records list 9 violations for this system; 4 are health-based, and the most recent began in October 2023.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
2,359
Service connections
2,161
Primary source
SW
Surface water
System type
CWS
Community water system
System record
How does Clearlake Oaks County Water District compare with other water systems in Lake County?
By EPA's size categories, Clearlake Oaks County Water District is a small system (501 to 3,300 people). Lake County has 81 active public water systems. Its population served is about 164% above the county average of 895 people per system, and accounts for 3.3% of the 72,454 people reported by systems filed under the county. Across California, the 7,479 active systems average 5,706 people each. Nationally, the average active community water system reports serving 6,703 people, so Clearlake Oaks County Water District is about 65% below that figure.
What does “community water system” mean?
A community water system serves at least 15 connections used by year-round residents, or regularly serves at least 25 year-round residents. Homes, apartments and mobile-home parks are served by these. California has 2,997 active community water systems, 40% of the state's 7,479 active systems. Surface water means the system draws its water from rivers, lakes, streams or reservoirs. 609 California systems (8.1%) list surface water as their primary source.
Who owns and regulates Clearlake Oaks County Water District?
EPA lists Clearlake Oaks County Water District 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. 17 of the 81 active systems in Lake County (21%) are also owned by a local government.
Does Clearlake Oaks County Water District have drinking water violations?
EPA's records list 9 violations for this system; 4 are health-based, and the most recent began in October 2023. The violations listed here began between July 1993 and October 2023. By type: 5 monitoring and reporting, 3 contaminant level above the legal limit and 1 required treatment not met. The contaminant or rule involved most often is Total trihalomethanes (TTHM) (3 of them). EPA lists 9 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 |
|---|---|---|---|---|
| 2023-10-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Total trihalomethanes (TTHM)code 2950 | Yes | Resolved |
| 2021-04-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Total trihalomethanes (TTHM)code 2950 | Yes | Resolved |
| 2019-10-01 | Monitoring and reportingFollow-up Or Routine LCR Tap M/R · code 52 | Lead and Copper Rulecode 5000 | No | Resolved |
| 2019-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
| 2017-10-01 | Monitoring and reportingMonitoring of Treatment (SWTR-Filter) · code 36 | Surface Water Treatment Rulecode 0200 | No | Resolved |
| 2006-07-01 | Required treatment not metTreatment Technique (SWTR and GWR) · code 41 | Surface Water Treatment Rulecode 0200 | Yes | Resolved |
| 2006-06-01 | Monitoring and reportingFollow-up Or Routine LCR Tap M/R · code 52 | Lead and Copper Rulecode 5000 | No | Resolved |
| 2005-10-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Total trihalomethanes (TTHM)code 2950 | Yes | Resolved |
| 1993-07-01 | Monitoring and reportingInitial Tap Sampling for Pb and Cu · code 51 | Lead and Copper Rulecode 5000 | No | Resolved |
All 9 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.
Clearlake Oaks County Water District: frequently asked questions
Who runs Clearlake Oaks County Water District?
Clearlake Oaks County Water District (PWSID CA1710001) is a community water system owned by a local government. It is regulated by the CA state drinking water program.
How many people does Clearlake Oaks County Water District serve?
Clearlake Oaks County Water District reports serving 2,359 people through 2,161 service connections in Lake County, California.
Where does Clearlake Oaks County Water District get its water?
EPA SDWIS lists this system's primary water source as surface water. Surface water means the system draws its water from rivers, lakes, streams or reservoirs.
Does Clearlake Oaks County Water District have any drinking water violations?
EPA's records list 9 violations for this system; 4 are health-based, and the most recent began in October 2023. 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 Clearlake Oaks County Water District'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 9 violations for this system; 4 are health-based, and the most recent began in October 2023. For current results, consult the system's annual water quality report, EPA ECHO, or the CA state drinking water program.
Where can I find Clearlake Oaks County Water District's water quality report?
As a community water system, Clearlake Oaks County Water District must deliver an annual water quality report, called a Consumer Confidence Report, to its customers by July 1 each year, covering the previous calendar year. The system can provide a copy on request.
Other water systems in Lake County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Highlands Mutual Water Company | Lake | 7,772 | Community | Surface water |
| Hidden Valley Lake Csd | Lake | 6,235 | Community | Groundwater |
| Konocti County Water District | Lake | 5,928 | Community | Surface water |
| Lakeport, City of | Lake | 4,762 | Community | Surface water |
| Golden State Water Co.-Clearlake System | Lake | 4,644 | Community | Surface water |
| Mt. Konocti Mutual Water Company | Lake | 4,360 | 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, “Clearlake Oaks County Water District, PWSID CA1710001, California”, https://aquacensus.com/water-systems/california/clearlake-oaks-county-water-district-ca1710001 (data as of October 1, 2026).