Public water system · IA6739095
ActiveOnawa Municipal Water Plant
At a glance
Onawa Municipal Water Plant (PWSID IA6739095) is an active community water system in Monona County, Iowa. It reports serving 2,906 people through 1,350 service connections. Its primary water source is groundwater, and EPA lists it as owned by a local government. EPA's records list one violation for this system; it is not health-based, and the most recent began in April 1988.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
2,906
Service connections
1,350
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Onawa Municipal Water Plant compare with other water systems in Monona County?
By EPA's size categories, Onawa Municipal Water Plant is a small system (501 to 3,300 people). Monona County has 14 active public water systems, and Onawa Municipal Water Plant is the largest of them by population served. Its population served is about 6.3 times the county average of 462 people per system, and accounts for 45% of the 6,465 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 Onawa Municipal Water Plant is about 57% 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. Iowa has 1,084 active community water systems, 59% of the state's 1,828 active systems. Groundwater means the system draws its water from wells or springs fed by underground aquifers. 1,502 Iowa systems (82%) list groundwater as their primary source.
Who owns and regulates Onawa Municipal Water Plant?
EPA lists Onawa Municipal Water Plant 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. 9 of the 14 active systems in Monona County (64%) are also owned by a local government.
Does Onawa Municipal Water Plant have drinking water violations?
EPA's records list one violation for this system; it is not health-based, and the most recent began in April 1988. By type: 1 monitoring and reporting. The contaminant or rule involved is Nitrate. EPA lists 1 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 |
|---|---|---|---|---|
| 1988-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
The one violation in EPA's records.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.
Onawa Municipal Water Plant: frequently asked questions
Who runs Onawa Municipal Water Plant?
Onawa Municipal Water Plant (PWSID IA6739095) is a community water system owned by a local government. It is regulated by the IA state drinking water program.
How many people does Onawa Municipal Water Plant serve?
Onawa Municipal Water Plant reports serving 2,906 people through 1,350 service connections in Monona County, Iowa.
Where does Onawa Municipal Water Plant 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 Onawa Municipal Water Plant have any drinking water violations?
EPA's records list one violation for this system; it is not health-based, and the most recent began in April 1988. 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 Onawa Municipal Water Plant'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. EPA's records list one violation for this system; it is not health-based, and the most recent began in April 1988. For current results, consult the system's annual water quality report, EPA ECHO, or the IA state drinking water program.
Where can I find Onawa Municipal Water Plant's water quality report?
As a community water system, Onawa Municipal Water Plant 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 Monona County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Mapleton Municipal Water Plant | Monona | 1,124 | Community | Groundwater |
| Whiting Water Supply | Monona | 727 | Community | Groundwater |
| Ute Water Supply | Monona | 338 | Community | Groundwater |
| Timber Ridge Lodge Recreation, Ltd. | Monona | 250 | Transient non-community | Groundwater |
| Onawa Koa | Monona | 250 | Transient non-community | Groundwater |
| Blencoe Municipal Waterworks | Monona | 224 | 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, “Onawa Municipal Water Plant, PWSID IA6739095, Iowa”, https://aquacensus.com/water-systems/iowa/onawa-municipal-water-plant-ia6739095 (data as of October 1, 2026).