Public water system record
Clearlake Oaks County Water District
Serves an area of Lake County, CA that includes Clearlake Oaks · 2,359 people served
Federal records show 2 health-based violations and 3 monitoring/reporting issues for Clearlake Oaks County Water District in the last ten years. The most serious issue in this window was a resolved Total Trihalomethanes (TTHMs) violation.
System profile
- Health-based violations, last 10 years
- 2
- Resolved
- 2
- Unresolved
- 0
- Any acute record
- No
- Monitoring issues, last 10 years
- 3
Key facts
- Clearlake Oaks County Water District draws water from 1 surface water intake.
- Highest measured level in the last 10 years: Total Trihalomethanes (TTHMs), 0.087 mg/L, federal limit 0.08 mg/L (1.1 times the limit), 2021.
- Most recent formal enforcement: compliance order (no penalty) by California, March 2023.
- Record on file since 1993, with 2 health-based violations before October 19, 2016.
- Lead pipe inventory: 0 lead and 0 unknown out of 1,887 service lines.
Check whether Clearlake Oaks County Water District serves your address
Health-based violations
Since October 2016Violation data reflects EPA records through March 2026. For the most current status, visit the EPA ECHO database.
| Contaminant | Rule family | Start date | Status | Acute |
|---|---|---|---|---|
|
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 83.5 µg/L, federal limit 80 µg/L (at or just above the limit)
|
220 | Oct 1, 2023 | Resolved | No |
|
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.087 mg/L, federal limit 0.08 mg/L (1.1 times the limit)
|
220 | Apr 1, 2021 | Resolved | No |
Monitoring and reporting issues
Since October 2016Missed tests or reports, not contaminants found above a limit.
| Issue | Start date | Status |
|---|---|---|
|
Lead and Copper Rule
Monitoring and reporting
|
Oct 1, 2019 | Resolved |
|
Nitrate
Monitoring and reporting
|
Jan 1, 2019 | Resolved |
|
Surface Water Treatment Rule
Monitoring and reporting
|
Oct 1, 2017 | Resolved |
Full record since 1993
EPA's records for Clearlake Oaks County Water District go back to 1993. Before October 19, 2016 they list 2 health-based violations (2 resolved) and 2 monitoring or reporting violations.
| Violations that began in | Health-based | Monitoring and reporting |
|---|---|---|
| 1990s | 0 | 1 |
| 2000s | 2 | 1 |
| October 19, 2016 to 2019 | 0 | 3 |
| 2020s | 2 | 0 |
Most recent health-based violation before October 19, 2016: Surface Water Treatment Rule, began July 2006, Resolved.
Show all 2 health-based violations before October 19, 2016
| Contaminant | Start date | Status |
|---|---|---|
|
Surface Water Treatment Rule
Treatment technique failure
|
Jul 1, 2006 | Resolved |
|
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.082 mg/L, federal limit 0.08 mg/L (at or just above the limit)
|
Oct 1, 2005 | Resolved |
Enforcement actions
California regulators took 7 formal enforcement actions against Clearlake Oaks County Water District between 2006 and 2023. The most recent was a compliance order (no penalty) in March 2023.
| Date | By | Action | Violations covered |
|---|---|---|---|
| Mar 14, 2023 | California | Compliance order (no penalty) | 1 violation (1 health-based): Total Trihalomethanes (TTHMs) |
| Sep 20, 2021 | California | Compliance order (no penalty) | 1 violation (1 health-based): Total Trihalomethanes (TTHMs) |
| May 11, 2020 | California | Compliance order (no penalty) | 1 violation: Nitrate |
| Feb 11, 2020 | California | Compliance order (no penalty) | 1 violation: Lead and Copper Rule |
| Oct 4, 2017 | California | Compliance order (no penalty) | 1 violation: Surface Water Treatment Rule |
| Nov 27, 2006 | California | Compliance order (no penalty) | 1 violation (1 health-based): Total Trihalomethanes (TTHMs) |
| Aug 15, 2006 | California | Compliance order (no penalty) | 1 violation (1 health-based): Surface Water Treatment Rule |
What the violations mean
Total Trihalomethanes (TTHMs)
2 incidentsDisinfection byproduct levels exceeded the federal limit
Long-term TTHM exposure may increase bladder cancer risk
Where the water comes from
Clearlake Oaks County Water District draws water from 1 surface water intake.
Annual water quality report
Clearlake Oaks County Water District must give its customers an annual water quality report (Consumer Confidence Report) by July 1, with the levels its tests found in the previous year.
Where the state allows it, systems serving fewer than 10,000 people may publish the report in a local newspaper or news site instead of mailing it, and must provide a copy on request.
Find a posted report with EPA's Consumer Confidence Report search
Testing your own water
To test the water at your tap, or a private well this record does not cover, use a laboratory certified for drinking water by California.
Certified drinking water labs by state EPA guidance for private wells