Public water system · WI1110111
ActiveRio Waterworks
At a glance
Rio Waterworks (PWSID WI1110111) is an active community water system in Columbia County, Wisconsin. It reports serving 1,095 people through 405 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, one is health-based, and the most recent began in October 2024.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
1,095
Service connections
405
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Rio Waterworks compare with other water systems in Columbia County?
By EPA's size categories, Rio Waterworks is a small system (501 to 3,300 people). Columbia County has 140 active public water systems. Its population served is about 137% above the county average of 463 people per system, and accounts for 1.7% of the 64,780 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 Rio Waterworks is well below 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 Rio Waterworks?
EPA lists Rio 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. 16 of the 140 active systems in Columbia County (11%) are also owned by a local government.
Does Rio Waterworks have drinking water violations?
Of the 12 most recent violations in EPA's records, one is health-based, and the most recent began in October 2024. The violations listed here began between July 2008 and October 2024. By type: 9 monitoring and reporting, 2 public notice, recordkeeping or other and 1 required treatment not met. The contaminant or rule involved most often is Nitrate (2 of them). EPA lists 10 as resolved and 2 as unaddressed. 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. Unaddressed means the violation is not resolved or archived and is not yet covered by formal enforcement.
| Began | Violation | Contaminant or rule | Health-based | Status |
|---|---|---|---|---|
| 2024-10-17 | Public notice, recordkeeping or otherPublic Notification Violation for NPDWR Violation · code 75 | Public Noticecode 7500 | No | Unaddressed |
| 2024-10-17 | Required treatment not metLSL Inventory · code 2E | Lead and Copper Rule Revisionscode 5200 | Yes | Unaddressed |
| 2024-01-01 | Monitoring and reportingLead Consumer Notice · code 66 | Lead and Copper Rulecode 5000 | No | Resolved |
| 2018-09-13 | Public notice, recordkeeping or otherNotification, State · code 05 | Groundwater Rulecode 0700 | No | Resolved |
| 2014-01-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Total trihalomethanes (TTHM)code 2950 | No | Resolved |
| 2014-01-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Haloacetic acids (HAA5)code 2456 | No | Resolved |
| 2010-07-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
| 2009-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Gross alpha (excluding radon and uranium)code 4000 | No | Resolved |
| 2009-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Combined Radium (-226 and -228)code 4010 | No | Resolved |
| 2009-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Radium-228code 4030 | No | Resolved |
| 2009-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Radium-228code 4030 | No | Resolved |
| 2008-07-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | 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.
Rio Waterworks: frequently asked questions
Who runs Rio Waterworks?
Rio Waterworks (PWSID WI1110111) is a community water system owned by a local government. It is regulated by the WI state drinking water program.
How many people does Rio Waterworks serve?
Rio Waterworks reports serving 1,095 people through 405 service connections in Columbia County, Wisconsin.
Where does Rio 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 Rio Waterworks have any drinking water violations?
Of the 12 most recent violations in EPA's records, one is health-based, and the most recent began in October 2024. 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 Rio 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, one is health-based, and the most recent began in October 2024. For current results, consult the system's annual water quality report, EPA ECHO, or the WI state drinking water program.
Where can I find Rio Waterworks' water quality report?
As a community water system, Rio 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 Columbia County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Portage Waterworks | Columbia | 10,437 | Community | Groundwater |
| Columbus Utilities | Columbia | 5,173 | Community | Groundwater |
| Wi Dot Rest Area 12 Dekorra West Bound | Columbia | 3,255 | Transient non-community | Groundwater |
| Wisconsin Dells Waterworks | Columbia | 3,232 | Community | Groundwater |
| Lodi Waterworks | Columbia | 3,146 | Community | Groundwater |
| Poynette Waterworks | Columbia | 2,520 | Community | Groundwater |
Related pages
Working with water-system records? Pro adds alerts, change history and CSV export ($49/mo); Enterprise adds full national files, the API and an MCP server for AI tools.
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, “Rio Waterworks, PWSID WI1110111, Wisconsin”, https://aquacensus.com/water-systems/wisconsin/rio-waterworks-wi1110111 (data as of October 1, 2026).