Clay County, South Dakota — public water systems
At a glance
4 active public water systems are filed under Clay County, South Dakota in EPA's SDWIS records, together reporting 17,173 people served. The largest is Vermillion, which reports serving 11,695 people. All 4 are community water systems serving people where they live.
Dataset updated . Source: EPA SDWIS/ECHO, refreshed quarterly.
Active systems
4
Population served
17.2K
Community systems
4
Groundwater share
75%
How does Clay County compare with other South Dakota counties?
Clay County has the 39th-most active public water systems among the 73 counties listed for active South Dakota systems in EPA records; among the 48 with 3 or more systems, the median has 6. Its systems report 17,173 people served in total, the 13th-largest county figure in the state and 1.8% of the statewide total. The average system here reports serving 4,293 people, about 3.1 times the South Dakota average of 1,387. 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 Clay County's drinking water come from?
By primary water source, Clay County's active systems draw on groundwater (2, 50%), purchased surface water (1, 25%) and purchased groundwater (1, 25%). Overall, 75% rely mainly on groundwater (including purchased groundwater) and 25% on surface water, compared with 76% and 24% across South Dakota. Groundwater means the system draws its water from wells or springs fed by underground aquifers. The county's largest system, Vermillion, draws primarily on groundwater.
What kinds of water systems operate in Clay County?
Clay County's active systems break down as 4 community systems (100%). 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. EPA lists their owner types as local government (75%) and private (25%).
Water systems in Clay County
🔒 Create a free account to export CSV| # | Water system | County | Population served | Type | Source |
|---|---|---|---|---|---|
| 1 | Vermillion | Clay | 11,695 | Community | Groundwater |
| 2 | Clay Rural Water System | Clay + 1 more | 4,780 | Community | Groundwater |
| 3 | Irene | Clay + 2 more | 422 | Community | Purchased surface water |
| 4 | Wakonda | Clay | 276 | Community | Purchased groundwater |
Clay County water systems: frequently asked questions
How many public water systems are in Clay County, South Dakota?
EPA's SDWIS records file 4 active public water systems under Clay County, South Dakota: 4 community systems (100%).
Who supplies drinking water in Clay County, SD?
The largest community water systems filed under Clay County are Vermillion (11,695 people served), Clay Rural Water System (4,780 people served) and Irene (422 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 Clay County's drinking water come from groundwater or surface water?
Of the 4 active public water systems in Clay County, 75% draw mainly on groundwater and 25% on surface water, counting purchased supplies. The largest system, Vermillion, uses groundwater.
Where can I find a water quality report for Clay 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. 4 community systems are filed under Clay 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 Clay 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 South Dakota water systems
- All South Dakota public water systems· 699 active
- Gregory County· 4 systems
- Davison County· 4 systems
- Hutchinson County· 4 systems
- Potter County· 4 systems
- Walworth County· 4 systems
- Aurora County· 4 systems
- How to find out who supplies your drinking water
- How to find and read your annual water quality report
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 Clay County, South Dakota”, https://aquacensus.com/water-systems/south-dakota/clay (data as of October 1, 2026).