County · South Dakota
Dewey County, South Dakota: drinking water records
This overview covers 7 ZIP codes and 5 community water systems in Dewey County. It also stands in for 0 ZIP codes whose utility has too little EPA data for a page of its own.
System population figures are summed from EPA registry records and can overlap where wholesalers and retail systems serve the same people. They are not a Census county-population estimate.
Water systems with the most complete records
| Water system | People served | PFAS survey results | PFAS found | Health-based violations | Lead, 9 in 10 homes at or below |
|---|---|---|---|---|---|
| Eagle Butte SD4600010 | 4,000 | 120 | 0 | 2 | 0 ppb |
| Tri-County Rural Water System SD4600112 | 2,190 | 120 | 0 | 0 | 4 ppb |
| Timber Lake SD4600411 | 499 | 0 | 0 | 0 | 5 ppb |
| T C & G Rural Water System SD4600143 | 166 | 0 | 0 | 0 | 2 ppb |
| Isabel SD4600175 | 145 | 0 | 0 | 0 | 2 ppb |
ZIP reports in Dewey County
No ZIP report in this county is published yet.
Sources and scope
EPA UCMR 5 occurrence data, samples collected 2023-01-03 – 2026-06-17, final release, August 2026 (file dated Aug 28, 2026); EPA SDWIS via ECHO, 2026Q2 extract (file dated Jul 9, 2026); EPA service-area boundaries v3.0; Census 2020 ZCTAs. Page generated 2026-09-03.
Counts cover the systems that report this county to EPA. A water system may cross county lines. "Found" means at least one result at or above the laboratory reporting level; it is not a compliance finding.