Saint Onge State Bank · Photo: Jon Roanhaus · Public domainLiving in St. Onge Township, SD: what to set up and who to call
Most mail in St. Onge Township goes to 57779 (97% of residents), one of 2 ZIP codes in town. Grace Balloch Memorial Library, 7.4 miles away, is the closest library to St. Onge Township.
I’m new in town
What to set up in St. Onge Township, and who provides it. Tap an answer for the details and where they come from.
Power, water and internet
Who to call to start service at a new address in St. Onge Township.
Power comes from Black Hills Energy
Black Hills Energy (Black Hills Power, Inc.), an investor-owned utility, serves all of St. Onge Township. Its homes paid an average of 15.1¢ per kWh in 2025, about $106 a month (its average across South Dakota).
Start or move service: blackhillspower.com · (800) 742-8948
Service territory: HIFLD Electric Retail Service Territories (map dated Aug 2023). Prices and customers: EIA-861, 2025.
Water comes from Saint Onge Sewer & Water Co
Saint Onge Sewer & Water Co supplies St. Onge Township: about 50% of residents live in its service area. About 50% of homes are outside any mapped community water system, most likely on private wells, which EPA doesn’t regulate. It draws ground water and serves 255 people in all.
No health-based violations reported to EPA in the five years to October 2026, like 77% of the 15,074 systems serving 101–500 people.
The latest lead result on file, the 90th percentile of homes sampled in Jan–Dec 2024, was 2.0 ppb, below the 15 ppb action level that applied. The highest in five years was 5.0 ppb. That’s higher than 70% of similar systems’ latest results.
The system’s full record: EPA ECHO report
EPA SDWIS via Envirofacts (violations pulled Oct 9, 2026) and ECHO (lead samples, 2026Q3); service area: EPA Community Water System Service Area Boundaries v3.0. Violations are counted by the start of their compliance period. SD4600287.
4 home internet providers serve St. Onge Township
49% of 203 addresses can get 100/20 Mbps; 6% can get fiber.
| Provider | Technology | Addresses | Fastest (Mbps) |
|---|---|---|---|
| CenturyLink | DSL | 68% | 60/5 |
| Bluepeak | Cable, Fiber | 49% | 5,000/5,000 |
| Wisp West, Celerity Internet | Fixed wireless | 100% | 100/20 |
| T-Mobile | Fixed wireless | 50% | 25/3 |
FCC National Broadband Map, as of December 2025. Availability as providers report it, not speeds people get.
We don’t have St. Onge Township’s trash rules yet
Pickup rules, the dump and recycling in St. Onge Township.
Where your child goes to school
Public school districts and the school path by grade.
Most of St. Onge Township (50%) is in Belle Fourche School District 09-1; parts are in Spearfish School District 40-2 (50%).
Test scores and every school: see Schools →U.S. Department of Education, NCES Common Core of Data, 2024–25. Enrollment rules and registration are the district’s.
Town hall and registering to vote
Who to call, and how to register.
Election office: FVAP local election office directory, updated Jul 2023; jurisdictions: EAC EAVS 2024. Registration rules and links: vote.gov, updated Aug 3, 2026.
St. Onge Township spans 2 ZIP codes
ZIP codes where St. Onge Township residents live, with the share of the town in each.
| ZIP | Post office name | Share of St. Onge Township | ZIP’s residents in St. Onge Township |
|---|---|---|---|
| 57779 | Saint Onge, SD | 97% | 87% |
| 57793 | Whitewood, SD | 3% | 0% |
Census 2020 ZIP Code Tabulation Areas, by census block; post office names: GeoNames (CC BY 4.0). ZIPs created since 2020 are missing.
Getting around, the ER and the library
One line each; the subject pages have the rest.
ER: CMS hospital data. Library: IMLS Public Libraries Survey, FY2024.
Questions about living in St. Onge Township
Who supplies St. Onge Township’s drinking water, and has it had violations?
Saint Onge Sewer & Water Co (EPA ID SD4600287). It reported no health-based violations to EPA in the five years to October 2026; 77% of systems its size had none. Its latest lead 90th percentile was 2.0 ppb (Jan–Dec 2024), against a 15 ppb action level.
Who provides electricity in St. Onge Township?
Black Hills Energy (Black Hills Power, Inc.), an investor-owned utility. Its homes paid about 15.1¢ per kWh in 2025 (EIA).
What internet providers serve St. Onge Township?
CenturyLink, Bluepeak, Wisp West, Celerity Internet, T-Mobile (FCC, as of December 2025).
What ZIP codes are in St. Onge Township?
57779 (97%), 57793 (3%), by share of residents. Census 2020 ZIP Code Tabulation Areas.
What school district is St. Onge Township in?
Belle Fourche School District 09-1. Parts of the city are in Spearfish School District 40-2.
How do I register to vote in St. Onge Township?
South Dakota has no online registration; you can register in person until 15 days before Election Day or by mail (received 15 days before). Elections here are run by the Lawrence County Auditor. Check your registration at vip.sdsos.gov.
Sources & dates
Every answer above names its source. Here they are with their dates.
- Water: EPA SDWIS (Envirofacts, pulled Oct 9, 2026), ECHO SDWA 2026Q3, EPA CWS Service Area Boundaries v3.0.
- Power: HIFLD Electric Retail Service Territories (map Aug 2023); EIA-861 final 2025.
- Trash: OpenStreetMap, Geofabrik extract of Oct 9, 2026. © OpenStreetMap contributors (ODbL).
- ZIP codes: Census 2020 ZCTA relationship files; GeoNames postal codes (CC BY 4.0).
- Schools: NCES Common Core of Data, 2024–25.
- Registration: vote.gov, updated Aug 3, 2026 (read Oct 10, 2026). Official sites and area codes: Wikidata.
- Election office: FVAP local election office directory (fetched Oct 10, 2026; each record dated), EAC EAVS 2024 jurisdictions; registration and lookup links from vote.gov’s state data, checked Oct 10, 2026.
- Internet: FCC National Broadband Map, as of December 2025.