B67/100
CLEARLAKE OAKS COUNTY WATER DISTRICT — Water Quality Report 2026
Serving 2,359 people · California
Water Source
Surface Water
County
—
System ID
CA1710001
Violations
9
Contaminant Test Results
1 contaminant above EPA health goals
| Contaminant | Detected | Limit (MCL) | Status |
|---|---|---|---|
Copper (90th percentile) | 2.80 mg/L | 1.30 mg/L | Over Limit |
EPA Violation History
1
Violation (last 5yr)
0
Unresolved
1
Health-Related
TIER 2Resolved
Exceeded the Maximum Contaminant Level (running average)
When: October 1, 2023 – December 31, 2023Rule: Stage 2 DBPREnforcement: Formal — state order issued
Understanding violation severity
Tier 1Urgent health risk. Utility must notify all customers within 24 hours.Tier 2Important health or treatment issue. Customers notified within 30 days.Tier 3Administrative or monitoring issue. Reported in the annual water quality report.
Source: EPA Safe Drinking Water Information System (SDWIS) · Updated quarterly
Frequently Asked Questions About CLEARLAKE OAKS COUNTY WATER DISTRICT
Is CLEARLAKE OAKS COUNTY WATER DISTRICT water safe to drink?
CLEARLAKE OAKS COUNTY WATER DISTRICT water receives a grade of B (67/100), which is considered good. Out of 9 contaminants tested, 1 exceed EPA legal limits. 1 contaminant(s) exceed non-enforceable health goals. The water meets federal safety standards.
What contaminants has CLEARLAKE OAKS COUNTY WATER DISTRICT detected?
9 contaminants were tested in CLEARLAKE OAKS COUNTY WATER DISTRICT's water. Notable contaminants include Copper (90th percentile). 1 exceed EPA legal limits (MCLs). 1 exceed EPA health goals (MCLGs).
Does CLEARLAKE OAKS COUNTY WATER DISTRICT have any EPA violations?
Yes, CLEARLAKE OAKS COUNTY WATER DISTRICT has 9 EPA violation(s) on record, with the most recent in 2023. Violation types include MCL, MR, TT. 4 are health-based violations.
How many people does CLEARLAKE OAKS COUNTY WATER DISTRICT serve?
CLEARLAKE OAKS COUNTY WATER DISTRICT serves approximately 2,359 people, California.
What type of water does CLEARLAKE OAKS COUNTY WATER DISTRICT provide?
CLEARLAKE OAKS COUNTY WATER DISTRICT sources its water from surface water. Surface water comes from rivers, lakes, or reservoirs and typically requires more extensive treatment. The utility's system ID is CA1710001.
How does CLEARLAKE OAKS COUNTY WATER DISTRICT compare to other utilities in California?
CLEARLAKE OAKS COUNTY WATER DISTRICT scores 67/100 with a grade of B (good). This is an above-average performance for utilities statewide. Visit our California state page for a full comparison of water systems.