Public water system · WI6320327
ActiveOnalaska Waterworks
At a glance
Onalaska Waterworks (PWSID WI6320327) is an active community water system in La Crosse County, Wisconsin. It reports serving 18,000 people through 5,110 service connections. Its primary water source is groundwater, and EPA lists it as owned by a local government. EPA's records list 3 violations for this system; 2 are health-based, and the most recent began in July 2010.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
18,000
Service connections
5,110
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Onalaska Waterworks compare with other water systems in La Crosse County?
By EPA's size categories, Onalaska Waterworks is a large system (10,001 to 100,000 people). La Crosse County has 122 active public water systems, and Onalaska Waterworks is the 2nd-largest of them by population served. Its population served is about 22 times the county average of 811 people per system, and accounts for 18% of the 98,888 people reported by systems filed under the county. Across Wisconsin, the 11,056 active systems average 469 people each. Nationally, the average active community water system reports serving 6,703 people, so Onalaska Waterworks is about 169% above 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. Wisconsin has 1,053 active community water systems, 9.5% of the state's 11,056 active systems. Groundwater means the system draws its water from wells or springs fed by underground aquifers. 10,978 Wisconsin systems (99%) list groundwater as their primary source.
Who owns and regulates Onalaska Waterworks?
EPA lists Onalaska Waterworks as owned by a local government. The WI state drinking water program is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act. 34 of the 122 active systems in La Crosse County (28%) are also owned by a local government.
Does Onalaska Waterworks have drinking water violations?
EPA's records list 3 violations for this system; 2 are health-based, and the most recent began in July 2010. The violations listed here began between August 1997 and July 2010. By type: 2 contaminant level above the legal limit and 1 monitoring and reporting. The contaminant or rule involved most often is Total coliform bacteria (TCR) (2 of them). EPA lists 3 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 |
|---|---|---|---|---|
| 2010-07-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 2001-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
| 1997-08-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
All 3 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.
Onalaska Waterworks: frequently asked questions
Who runs Onalaska Waterworks?
Onalaska Waterworks (PWSID WI6320327) is a community water system owned by a local government. It is regulated by the WI state drinking water program.
How many people does Onalaska Waterworks serve?
Onalaska Waterworks reports serving 18,000 people through 5,110 service connections in La Crosse County, Wisconsin.
Where does Onalaska Waterworks get its water?
EPA SDWIS lists this system's primary water source as groundwater. Groundwater means the system draws its water from wells or springs fed by underground aquifers.
Does Onalaska Waterworks have any drinking water violations?
EPA's records list 3 violations for this system; 2 are health-based, and the most recent began in July 2010. 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 Onalaska Waterworks' 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 3 violations for this system; 2 are health-based, and the most recent began in July 2010. For current results, consult the system's annual water quality report, EPA ECHO, or the WI state drinking water program.
Where can I find Onalaska Waterworks' water quality report?
As a community water system, Onalaska Waterworks 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 La Crosse County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| La Crosse Waterworks | La Crosse | 53,000 | Community | Groundwater |
| Holmen Waterworks | La Crosse | 10,147 | Community | Groundwater |
| West Salem Waterworks | La Crosse | 5,045 | Community | Groundwater |
| Bangor Waterworks | La Crosse | 1,520 | Community | Groundwater |
| Shelby Tn of Wedgewood Vly | La Crosse | 1,020 | Community | Groundwater |
| Celebrations on the River | La Crosse | 815 | Non-transient non-community | Groundwater |
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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, “Onalaska Waterworks, PWSID WI6320327, Wisconsin”, https://aquacensus.com/water-systems/wisconsin/onalaska-waterworks-wi6320327 (data as of October 1, 2026).