A81/100
ONALASKA WATERWORKS — Water Quality Report 2026
Serving 18,000 people · Wisconsin
Water Source
Groundwater
County
—
System ID
WI6320327
Violations
3
Contaminant Test Results
1 contaminant above EPA health goals
| Contaminant | Detected | Limit (MCL) | Status |
|---|---|---|---|
Copper (90th percentile) | 1.53 mg/L | 1.30 mg/L | Over Limit |
EPA Violation History
No violations in the past 5 years
Full EPA compliance since 2010.
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 ONALASKA WATERWORKS
Is ONALASKA WATERWORKS water safe to drink?
ONALASKA WATERWORKS water receives a grade of A (81/100), which is considered excellent. Out of 67 contaminants tested, 1 exceed EPA legal limits. 1 contaminant(s) exceed non-enforceable health goals. The water meets federal safety standards.
What contaminants has ONALASKA WATERWORKS detected?
67 contaminants were tested in ONALASKA WATERWORKS's water. Notable contaminants include Copper (90th percentile). 1 exceed EPA legal limits (MCLs). 1 exceed EPA health goals (MCLGs).
Does ONALASKA WATERWORKS have any EPA violations?
Yes, ONALASKA WATERWORKS has 3 EPA violation(s) on record, with the most recent in 2010. Violation types include MCL, MR. 2 are health-based violations.
How many people does ONALASKA WATERWORKS serve?
ONALASKA WATERWORKS serves approximately 18,000 people, Wisconsin. The system provides water to 1 community: Onalaska.
What type of water does ONALASKA WATERWORKS provide?
ONALASKA WATERWORKS sources its water from groundwater. Groundwater is pumped from underground aquifers, which often provides natural filtration. The utility's system ID is WI6320327.
How does ONALASKA WATERWORKS compare to other utilities in Wisconsin?
ONALASKA WATERWORKS scores 81/100 with a grade of A (excellent). This places it among the higher-performing utilities in the state. Visit our Wisconsin state page for a full comparison of water systems.