Public water system · IA6273005
ActiveOskaloosa Municipal Water Dept
At a glance
Oskaloosa Municipal Water Dept (PWSID IA6273005) is an active community water system in Mahaska County, Iowa. It reports serving 12,808 people through 5,400 service connections. Its primary water source is groundwater under influence of surface water, and EPA lists it as owned by a local government. Of the 12 most recent violations in EPA's records, 6 are health-based, and the most recent began in January 2024.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
12,808
Service connections
5,400
Primary source
GU
Groundwater under influence of surface water
System type
CWS
Community water system
System record
How does Oskaloosa Municipal Water Dept compare with other water systems in Mahaska County?
By EPA's size categories, Oskaloosa Municipal Water Dept is a large system (10,001 to 100,000 people). Mahaska County has 4 active public water systems, and Oskaloosa Municipal Water Dept is the largest of them by population served. Its population served is about twice the county average of 6,040 people per system, and accounts for 53% of the 24,159 people reported by systems filed under the county. Across Iowa, the 1,828 active systems average 1,718 people each. Nationally, the average active community water system reports serving 6,703 people, so Oskaloosa Municipal Water Dept is about twice 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. Iowa has 1,084 active community water systems, 59% of the state's 1,828 active systems. Groundwater under the influence of surface water is well or spring water that the regulator has found to be affected by nearby surface water, so it is regulated under the surface-water treatment rules. 7 Iowa systems (0.4%) list groundwater under influence of surface water as their primary source.
Who owns and regulates Oskaloosa Municipal Water Dept?
EPA lists Oskaloosa Municipal Water Dept as owned by a local government. The IA state drinking water program is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act. 2 of the 4 active systems in Mahaska County (50%) are also owned by a local government.
Does Oskaloosa Municipal Water Dept have drinking water violations?
Of the 12 most recent violations in EPA's records, 6 are health-based, and the most recent began in January 2024. The violations listed here began between May 1999 and January 2024. By type: 5 monitoring and reporting, 4 required treatment not met, 2 contaminant level above the legal limit and 1 monitoring. The contaminant or rule involved most often is Interim Enhanced Surface Water Treatment Rule (4 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 |
|---|---|---|---|---|
| 2024-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Di(2-ethylhexyl) phthalatecode 2039 | No | Resolved |
| 2023-10-01 | Monitoring and reportingMonitoring, Regular · code 03 | Di(2-ethylhexyl) phthalatecode 2039 | No | Resolved |
| 2021-02-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2015-08-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 2014-10-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Carbon, totalcode 2920 | No | Resolved |
| 2012-04-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Carbon, totalcode 2920 | No | Resolved |
| 2011-02-01 | Required treatment not metSingle Turbidity Exceed (Enhanced SWTR) · code 43 | Interim Enhanced Surface Water Treatment Rulecode 0300 | Yes | Resolved |
| 2009-09-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 2008-10-01 | Required treatment not metMonthly Turbidity Exceed (Enhanced SWTR) · code 44 | Interim Enhanced Surface Water Treatment Rulecode 0300 | Yes | Resolved |
| 2007-08-01 | Required treatment not metMonthly Turbidity Exceed (Enhanced SWTR) · code 44 | Interim Enhanced Surface Water Treatment Rulecode 0300 | Yes | Resolved |
| 2007-05-01 | Required treatment not metMonthly Turbidity Exceed (Enhanced SWTR) · code 44 | Interim Enhanced Surface Water Treatment Rulecode 0300 | Yes | Resolved |
| 1999-05-01 | Monitoring and reportingMonitoring, Routine Minor (TCR) · code 24 | Total coliform bacteria (TCR)code 3100 | 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.
Oskaloosa Municipal Water Dept: frequently asked questions
Who runs Oskaloosa Municipal Water Dept?
Oskaloosa Municipal Water Dept (PWSID IA6273005) is a community water system owned by a local government. It is regulated by the IA state drinking water program.
How many people does Oskaloosa Municipal Water Dept serve?
Oskaloosa Municipal Water Dept reports serving 12,808 people through 5,400 service connections in Mahaska County, Iowa.
Where does Oskaloosa Municipal Water Dept get its water?
EPA SDWIS lists this system's primary water source as groundwater under influence of surface water. Groundwater under the influence of surface water is well or spring water that the regulator has found to be affected by nearby surface water, so it is regulated under the surface-water treatment rules.
Does Oskaloosa Municipal Water Dept have any drinking water violations?
Of the 12 most recent violations in EPA's records, 6 are health-based, and the most recent began in January 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 Oskaloosa Municipal Water Dept's 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, 6 are health-based, and the most recent began in January 2024. For current results, consult the system's annual water quality report, EPA ECHO, or the IA state drinking water program.
Where can I find Oskaloosa Municipal Water Dept's water quality report?
As a community water system, Oskaloosa Municipal Water Dept 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 Mahaska County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Mahaska Rural Water System, Inc.. | Mahaska | 9,818 | Community | Groundwater |
| Mahaska Rural Water (New Sharon) | Mahaska | 1,368 | Community | Groundwater |
| Oak Creek MHP | Mahaska | 165 | Community | Purchased groundwater under influence |
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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, “Oskaloosa Municipal Water Dept, PWSID IA6273005, Iowa”, https://aquacensus.com/water-systems/iowa/oskaloosa-municipal-water-dept-ia6273005 (data as of October 1, 2026).