Dewey County, South Dakota — public water systems
At a glance
5 active public water systems are filed under Dewey County, South Dakota in EPA's SDWIS records, together reporting 7,000 people served. The largest is Eagle Butte, which reports serving 4,000 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
7K
Community systems
5
Groundwater share
40%
How does Dewey County compare with other South Dakota counties?
Dewey County has the 31st-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 7,000 people served in total, the 27th-largest county figure in the state and 0.7% of the statewide total. The average system here reports serving 1,400 people, roughly in line with 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 Dewey County's drinking water come from?
By primary water source, Dewey County's active systems draw on purchased surface water (2, 40%), groundwater (2, 40%) and surface water (1, 20%). Overall, 40% rely mainly on groundwater (including purchased groundwater) and 60% on surface water, compared with 76% and 24% across South Dakota. Purchased surface water means the system buys surface water from another public water system rather than drawing its own. The county's largest system, Eagle Butte, draws primarily on purchased surface water.
What kinds of water systems operate in Dewey County?
Dewey 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 (60%) and private (40%).
Water systems in Dewey County
🔒 Create a free account to export CSV| # | Water system | County | Population served | Type | Source |
|---|---|---|---|---|---|
| 1 | Eagle Butte | Dewey | 4,000 | Community | Purchased surface water |
| 2 | Tri-County Rural Water System | Dewey + 2 more | 2,190 | Community | Surface water |
| 3 | Timber Lake | Dewey | 499 | Community | Groundwater |
| 4 | T C & G Rural Water System | Dewey | 166 | Community | Groundwater |
| 5 | Isabel | Dewey | 145 | Community | Purchased surface water |
Dewey County water systems: frequently asked questions
How many public water systems are in Dewey County, South Dakota?
EPA's SDWIS records file 5 active public water systems under Dewey County, South Dakota: 5 community systems (100%).
Who supplies drinking water in Dewey County, SD?
The largest community water systems filed under Dewey County are Eagle Butte (4,000 people served), Tri-County Rural Water System (2,190 people served) and Timber Lake (499 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 Dewey County's drinking water come from groundwater or surface water?
Of the 5 active public water systems in Dewey County, 40% draw mainly on groundwater and 60% on surface water, counting purchased supplies. The largest system, Eagle Butte, uses purchased surface water.
Where can I find a water quality report for Dewey 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 Dewey 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 Dewey 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
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 Dewey County, South Dakota”, https://aquacensus.com/water-systems/south-dakota/dewey (data as of October 1, 2026).