County · South Dakota
Lake County, South Dakota: drinking water records
This overview covers 7 ZIP codes and 6 community water systems in Lake 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 |
|---|---|---|---|---|---|
| Madison SD4600199 | 6,191 | 120 | 0 | 0 | 2 ppb |
| Big Sioux Community Water System SD4600429 | 5,800 | 180 | 0 | 0 | 1 ppb |
| Ramona SD4600252 | 159 | 0 | 0 | 1 | 2 ppb |
| Kingbrook III Rural Water System SD4600874 | 2,888 | 0 | 0 | 0 | 3 ppb |
| Chester Sanitary District SD4600088 | 363 | 0 | 0 | 0 | 1 ppb |
| Wentworth SD4600419 | 181 | 0 | 0 | 0 | 0 ppb |
ZIP reports in Lake 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.