Public water system · WI1280108
ActiveLake Mills Waterworks
At a glance
Lake Mills Waterworks (PWSID WI1280108) is an active community water system in Jefferson County, Wisconsin. It reports serving 6,211 people through 2,607 service connections. Its primary water source is groundwater, and EPA lists it as owned by a local government. Of the 12 most recent violations in EPA's records, 3 are health-based, and the most recent began in September 2022.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
6,211
Service connections
2,607
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Lake Mills Waterworks compare with other water systems in Jefferson County?
By EPA's size categories, Lake Mills Waterworks is a medium system (3,301 to 10,000 people). Jefferson County has 195 active public water systems, and Lake Mills Waterworks is the 4th-largest of them by population served. Its population served is about 14 times the county average of 453 people per system, and accounts for 7% of the 88,343 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 Lake Mills Waterworks is roughly in line with 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 Lake Mills Waterworks?
EPA lists Lake Mills 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 195 active systems in Jefferson County (17%) are also owned by a local government.
Does Lake Mills Waterworks have drinking water violations?
Of the 12 most recent violations in EPA's records, 3 are health-based, and the most recent began in September 2022. The violations listed here began between January 2017 and September 2022. By type: 5 monitoring and reporting, 4 public notice, recordkeeping or other, 2 required treatment not met and 1 contaminant level above the legal limit. The contaminant or rule involved most often is Lead and Copper Rule (7 of them). EPA lists 12 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 |
|---|---|---|---|---|
| 2022-09-17 | Required treatment not metOCCT/SOWT Treatment Installation/Demonstration · code 58 | Lead and Copper Rulecode 5000 | Yes | Resolved |
| 2020-07-01 | Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71 | Consumer Confidence Rulecode 7000 | No | Resolved |
| 2020-07-01 | Public notice, recordkeeping or otherConsumer Confidence Report Inadequate Reporting · code 72 | Consumer Confidence Rulecode 7000 | No | Resolved |
| 2018-01-01 | Public notice, recordkeeping or otherPublic Notification Violation for NPDWR Violation · code 75 | Public Noticecode 7500 | No | Resolved |
| 2017-10-01 | Required treatment not metOCCT/SOWT Study/Recommendation · code 57 | Lead and Copper Rulecode 5000 | Yes | Resolved |
| 2017-07-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Combined Radium (-226 and -228)code 4010 | Yes | Resolved |
| 2017-07-01 | Monitoring and reportingFollow-up Or Routine LCR Tap M/R · code 52 | Lead and Copper Rulecode 5000 | No | Resolved |
| 2017-06-23 | Public notice, recordkeeping or otherPublic Notification Violation for NPDWR Violation · code 75 | Public Noticecode 7500 | No | Resolved |
| 2017-04-01 | Monitoring and reportingLead Consumer Notice · code 66 | Lead and Copper Rulecode 5000 | No | Resolved |
| 2017-01-01 | Monitoring and reportingInitial, Follow-up, or Routine Source Water M/R · code 56 | Lead and Copper Rulecode 5000 | No | Resolved |
| 2017-01-01 | Monitoring and reportingWater Quality Parameter M/R · code 53 | Lead and Copper Rulecode 5000 | No | Resolved |
| 2017-01-01 | Monitoring and reportingWater Quality Parameter M/R · code 53 | Lead and Copper Rulecode 5000 | No | Resolved |
The 12 most recent 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.
Lake Mills Waterworks: frequently asked questions
Who runs Lake Mills Waterworks?
Lake Mills Waterworks (PWSID WI1280108) is a community water system owned by a local government. It is regulated by the WI state drinking water program.
How many people does Lake Mills Waterworks serve?
Lake Mills Waterworks reports serving 6,211 people through 2,607 service connections in Jefferson County, Wisconsin.
Where does Lake Mills 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 Lake Mills Waterworks have any drinking water violations?
Of the 12 most recent violations in EPA's records, 3 are health-based, and the most recent began in September 2022. 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 Lake Mills 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. Of the 12 most recent violations in EPA's records, 3 are health-based, and the most recent began in September 2022. For current results, consult the system's annual water quality report, EPA ECHO, or the WI state drinking water program.
Where can I find Lake Mills Waterworks' water quality report?
As a community water system, Lake Mills 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 Jefferson County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Watertown Waterworks | Jefferson | 23,945 | Community | Groundwater |
| Fort Atkinson Waterworks | Jefferson | 12,390 | Community | Groundwater |
| Jefferson Waterworks | Jefferson | 7,926 | Community | Groundwater |
| Waterloo Waterworks | Jefferson | 3,520 | Community | Groundwater |
| Johnson Creek Waterworks | Jefferson | 3,318 | Community | Groundwater |
| Wi Dot Rest Area 13 Aztalan | Jefferson | 1,904 | 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, “Lake Mills Waterworks, PWSID WI1280108, Wisconsin”, https://aquacensus.com/water-systems/wisconsin/lake-mills-waterworks-wi1280108 (data as of October 1, 2026).