We found 16 public water systems in Dewey county (ordered by population size).
| Name | Areas served | Population served | Contaminant count | Violation count |
|---|---|---|---|---|
| Eagle Butte | Eagle Butte | 4,000 | 0 | 18 |
| Tri-county Rural Water System | Eagle Butte, Ridgeview | 2,880 | 0 | 64 |
| Timber Lake | Timber Lake | 435 | 0 | 103 |
| T C & G Rural Water System | Glencross, Mobridge | 170 | 0 | 9 |
| Cheyenne River Water Authority | Swift Bird | 150 | 0 | 0 |
| Isabel | Isabel | 135 | 0 | 103 |
| Cheyenne River Water Authority | Blackfoot | 94 | 0 | 0 |
| Cheyenne River Water Authority | Thunder Butte | 75 | 0 | 0 |
| Cheyenne River Bia Agency | Whitehorse Sch | 70 | 0 | 0 |
| Cheyenne River Water Authority | Bear Creek | 65 | 0 | 0 |
| Harding Motel | County of Dewey | 64 | 0 | 0 |
| Cheyenne River Water Authority | Bridger | 60 | 0 | 0 |
| Cheyenne River Bia Agency | Bridger School | 28 | 0 | 0 |
| Cheyenne River Water Authority | Iron Lightning | 26 | 0 | 0 |
| Gfp 14-a/little Moreau Rec Area | County of Dewey | 25 | 0 | 0 |
| Gfp 14-b/little Moreau Lake | County of Dewey | 25 | 0 | 0 |