Spearfish Post Office (Old) · Photo: Magicpiano · CC BY-SA 4.0Living in Mountain Plains, SD: what to set up and who to call
An EPA health-based violation from 2025 is still open for Mountain Plains 2 Homeowners Assoc. Mountain Plains has no town government of its own, so Lawrence County runs its elections and most services, and its children attend Spearfish School District 40-2.
I’m new in town
What to set up in Mountain Plains, 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 Mountain Plains.
Power comes from Black Hills Energy
Black Hills Energy (Black Hills Power, Inc.), an investor-owned utility, serves all of Mountain Plains. 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 Mountain Plains 2 Homeowners Assoc
Mountain Plains 2 Homeowners Assoc supplies Mountain Plains: about 75% of residents live in its service area. About 25% 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 268 people in all.
1 health-based violation reported to EPA in the five years to October 2026: a groundwater treatment requirement (Groundwater Rule), beginning Oct 2025. 77% of the 15,074 systems serving 101–500 people had none. 1 older violation is still open, since 2025: a groundwater treatment requirement (Groundwater Rule), per EPA’s records.
The latest lead result on file, the 90th percentile of homes sampled in Jan–Dec 2025, was 1.0 ppb, below the 15 ppb action level that applied. That’s higher than 52% 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. SD4602169.
5 home internet providers serve Mountain Plains
100% of 167 addresses can get 100/20 Mbps; 97% can get fiber.
| Provider | Technology | Addresses | Fastest (Mbps) |
|---|---|---|---|
| Bluepeak | Fiber, Cable | 99% | 5,000/5,000 |
| CenturyLink | DSL | 86% | 60/5 |
| Wisp West, Celerity Internet | Fixed wireless | 100% | 100/20 |
| T-Mobile | Fixed wireless | 54% | 25/3 |
| AT&T | Fixed wireless | 13% | 25/3 |
FCC National Broadband Map, as of December 2025. Availability as providers report it, not speeds people get.
We don’t have Mountain Plains’ trash rules yet
Pickup rules, the dump and recycling in Mountain Plains.
Where your child goes to school
Public school districts and the school path by grade.
Mountain Plains is in Spearfish School District 40-2.
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.
No town hall: the county runs things
Mountain Plains is unincorporated, so Lawrence County is the local government.
Election office: FVAP local election office directory, updated Jul 2023; jurisdictions: EAC EAVS 2024. Registration rules and links: vote.gov, updated Aug 3, 2026.
Mountain Plains is in ZIP code 57783
ZIP codes where Mountain Plains residents live, with the share of the town in each.
| ZIP | Post office name | Share of Mountain Plains | ZIP’s residents in Mountain Plains |
|---|---|---|---|
| 57783 | Spearfish, SD | 100% | 2% |
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 Mountain Plains
Who supplies Mountain Plains’ drinking water, and has it had violations?
Mountain Plains 2 Homeowners Assoc (EPA ID SD4602169). It reported 1 health-based violation to EPA in the five years to October 2026: a groundwater treatment requirement (Groundwater Rule). 77% of systems its size had none. Its latest lead 90th percentile was 1.0 ppb (Jan–Dec 2025), against a 15 ppb action level.
Who provides electricity in Mountain Plains?
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 Mountain Plains?
Bluepeak, CenturyLink, Wisp West, Celerity Internet, T-Mobile, AT&T (FCC, as of December 2025).
What ZIP codes are in Mountain Plains?
57783. Census 2020 ZIP Code Tabulation Areas.
What school district is Mountain Plains in?
Spearfish School District 40-2.
How do I register to vote in Mountain Plains?
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.