F0/100
Colusa Southern System — Water Quality Report 2026
Serving 3,474 people · California
Water Source
Groundwater
County
—
System ID
090605047
Violations
147
Contaminant Test Results
1 contaminant above EPA health goals
| Contaminant | Detected | Limit (MCL) | Status |
|---|---|---|---|
Lead (90th percentile) | 0.005 mg/L | 0.015 mg/L | Above Goal |
EPA Violation History
No violations in the past 5 years
Full EPA compliance since 2005.
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 Colusa Southern System
Is Colusa Southern System water safe to drink?
Colusa Southern System water receives a grade of F (0/100), which is considered failing. 0 contaminant(s) exceed EPA legal limits and 147 violation(s) are on record. Customers may want to consider using a water filter.
What contaminants has Colusa Southern System detected?
31 contaminants were tested in Colusa Southern System's water. Notable contaminants include Lead (90th percentile). No contaminants exceed EPA legal limits. 1 exceed EPA health goals (MCLGs).
Does Colusa Southern System have any EPA violations?
Yes, Colusa Southern System has 147 EPA violation(s) on record, with the most recent in 2005. Violation types include Other, MR.
How many people does Colusa Southern System serve?
Colusa Southern System serves approximately 3,474 people, California.
What type of water does Colusa Southern System provide?
Colusa Southern System sources its water from groundwater. Groundwater is pumped from underground aquifers, which often provides natural filtration. The utility's system ID is 090605047.
How does Colusa Southern System compare to other utilities in California?
Colusa Southern System scores 0/100 with a grade of F (failing). This score suggests significant water quality concerns relative to other utilities. Visit our California state page for a full comparison of water systems.