Monona County, Iowa — public water systems
At a glance
14 active public water systems are filed under Monona County, Iowa in EPA's SDWIS records, together reporting 6,465 people served. The largest is Onawa Municipal Water Plant, which reports serving 2,906 people. 8 are community water systems serving people where they live; the other 6 are non-community systems, such as schools, workplaces, campgrounds and gas stations with their own supply.
Dataset updated . Source: EPA SDWIS/ECHO, refreshed quarterly.
Active systems
14
Population served
6.5K
Community systems
8
Groundwater share
100%
How does Monona County compare with other Iowa counties?
Monona County has the 46th-most active public water systems among the 114 counties listed for active Iowa systems in EPA records; among the 96 with 3 or more systems, the median has 14. Its systems report 6,465 people served in total, the 85th-largest county figure in the state and 0.2% of the statewide total. The average system here reports serving 462 people, well below the Iowa average of 1,718. Population figures are what each system reports; people served by more than one system, such as a wholesaler and the town that buys from it, are counted by each.
Where does Monona County's drinking water come from?
By primary water source, Monona County's active systems draw on groundwater (14, 100%). Overall, all rely mainly on groundwater (including purchased groundwater) and none on surface water, compared with 92% and 7.8% across Iowa. Groundwater means the system draws its water from wells or springs fed by underground aquifers. The county's largest system, Onawa Municipal Water Plant, draws primarily on groundwater.
What kinds of water systems operate in Monona County?
Monona County's active systems break down as 8 community systems (57%) and 6 transient non-community systems (43%). 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. A transient non-community water system serves places where people do not stay long, such as gas stations and campgrounds, and regularly serves at least 25 people a day for at least 60 days a year. EPA lists their owner types as local government (64%), private (29%) and state government (7.1%).
Water systems in Monona County
🔒 Create a free account to export CSV| # | Water system | County | Population served | Type | Source |
|---|---|---|---|---|---|
| 1 | Onawa Municipal Water Plant | Monona | 2,906 | Community | Groundwater |
| 2 | Mapleton Municipal Water Plant | Monona | 1,124 | Community | Groundwater |
| 3 | Whiting Water Supply | Monona | 727 | Community | Groundwater |
| 4 | Ute Water Supply | Monona | 338 | Community | Groundwater |
| 5 | Timber Ridge Lodge Recreation, Ltd. | Monona | 250 | Transient non-community | Groundwater |
| 6 | Onawa Koa | Monona | 250 | Transient non-community | Groundwater |
| 7 | Blencoe Municipal Waterworks | Monona | 224 | Community | Groundwater |
| 8 | Moorhead Water Supply | Monona | 189 | Community | Groundwater |
| 9 | Soldier Water Supply | Monona | 180 | Community | Groundwater |
| 10 | Castana Municipal Water Supply | Monona | 103 | Community | Groundwater |
| 11 | Lewis and Clark State Park | Monona | 67 | Transient non-community | Groundwater |
| 12 | Divide Hill Bar & Grill | Monona | 50 | Transient non-community | Groundwater |
| 13 | Peters Park | Monona | 32 | Transient non-community | Groundwater |
| 14 | Sunset at the Oasis Rv Campground | Monona | 25 | Transient non-community | Groundwater |
Monona County water systems: frequently asked questions
How many public water systems are in Monona County, Iowa?
EPA's SDWIS records file 14 active public water systems under Monona County, Iowa: 8 community systems (57%) and 6 transient non-community systems (43%).
Who supplies drinking water in Monona County, IA?
The largest community water systems filed under Monona County are Onawa Municipal Water Plant (2,906 people served), Mapleton Municipal Water Plant (1,124 people served) and Whiting Water Supply (727 people served). Which system serves a particular address depends on its service area, which EPA's SDWIS records do not include; a water bill or the local utility can confirm it.
Does Monona County's drinking water come from groundwater or surface water?
Of the 14 active public water systems in Monona County, all draw mainly on groundwater and none on surface water, counting purchased supplies. The largest system, Onawa Municipal Water Plant, uses groundwater.
Where can I find a water quality report for Monona County?
Each community water system must deliver an annual water quality report, called a Consumer Confidence Report, to its customers by July 1, covering the previous calendar year. 8 community systems are filed under Monona County, so the report to look for is the one from the system that supplies your address.
How can I check violations for a water system in Monona County?
Open the system's profile from the list on this page. Each profile shows the most recent Safe Drinking Water Act violations in EPA's records, with plain-English labels and whether each one is resolved. For current compliance status, EPA ECHO is the primary source.
More Iowa water systems
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, “Public water systems in Monona County, Iowa”, https://aquacensus.com/water-systems/iowa/monona (data as of October 1, 2026).