Lake County, South Dakota — public water systems
At a glance
5 active public water systems are filed under Lake County, South Dakota in EPA's SDWIS records, together reporting 9,782 people served. The largest is Madison, which reports serving 6,191 people. All 5 are community water systems serving people where they live.
Dataset updated . Source: EPA SDWIS/ECHO, refreshed quarterly.
Active systems
5
Population served
9.8K
Community systems
5
Groundwater share
100%
How does Lake County compare with other South Dakota counties?
Lake County has the 33rd-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 9,782 people served in total, the 19th-largest county figure in the state and 1% of the statewide total. The average system here reports serving 1,956 people, about 41% above 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 Lake County's drinking water come from?
By primary water source, Lake County's active systems draw on purchased groundwater (3, 60%) and groundwater (2, 40%). Overall, all rely mainly on groundwater (including purchased groundwater) and none on surface water, compared with 76% and 24% across South Dakota. Purchased groundwater means the system buys groundwater from another public water system rather than drawing its own. The county's largest system, Madison, draws primarily on groundwater.
What kinds of water systems operate in Lake County?
Lake County's active systems break down as 5 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 (80%) and private (20%).
Water systems in Lake County
🔒 Create a free account to export CSV| # | Water system | County | Population served | Type | Source |
|---|---|---|---|---|---|
| 1 | Madison | Lake | 6,191 | Community | Groundwater |
| 2 | Kingbrook Iii Rural Water System | Lake | 2,888 | Community | Groundwater |
| 3 | Chester Sanitary District | Lake | 363 | Community | Purchased groundwater |
| 4 | Wentworth | Lake | 181 | Community | Purchased groundwater |
| 5 | Ramona | Lake | 159 | Community | Purchased groundwater |
Also serving Lake County
These systems serve several counties, including Lake County. EPA lists another county first for them, so they are not included in the counts above.
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Big Sioux Community Water System | Moody + 2 more | 5,800 | Community | Groundwater |
Lake County water systems: frequently asked questions
How many public water systems are in Lake County, South Dakota?
EPA's SDWIS records file 5 active public water systems under Lake County, South Dakota: 5 community systems (100%). At least 1 more system is listed under another county but also serve Lake County.
Who supplies drinking water in Lake County, SD?
The largest community water systems filed under Lake County are Madison (6,191 people served), Kingbrook Iii Rural Water System (2,888 people served) and Chester Sanitary District (363 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 Lake County's drinking water come from groundwater or surface water?
Of the 5 active public water systems in Lake County, all draw mainly on groundwater and none on surface water, counting purchased supplies. The largest system, Madison, uses groundwater.
Where can I find a water quality report for Lake 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. 5 community systems are filed under Lake 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 Lake 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
- Charles Mix County· 6 systems
- Grant County· 5 systems
- Dewey County· 5 systems
- Douglas County· 5 systems
- Sanborn County· 5 systems
- Gregory 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 Lake County, South Dakota”, https://aquacensus.com/water-systems/south-dakota/lake (data as of October 1, 2026).