Photo: Natecation · CC BY-SA 4.0Living in Big Arm, MT: what to set up and who to call
Big Arm has no town government of its own, so Lake County runs its elections and most services, and its children attend Polson Elementary School District. Tap water in Big Arm comes from Big Arm Water System, which has a clean five-year EPA record (about 23% of systems its size had a health-based violation) and a latest lead result of 1.0 ppb.
I’m new in town
What to set up in Big Arm, 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 Big Arm.
Power comes from NorthWestern Energy
NorthWestern Energy (NorthWestern Energy LLC - (MT)), an investor-owned utility, serves all of Big Arm. Its homes paid an average of 14.4¢ per kWh in 2025, about $102 a month (its average across Montana, for customers on its standard service). Montana lets you buy power from another supplier; 0% of NorthWestern Energy’s home customers do, and NorthWestern Energy still delivers it.
Start or move service: northwesternenergy.com · (888) 467-2669
Service territory: HIFLD Electric Retail Service Territories (map dated Aug 2023). Prices and customers: EIA-861, 2025.
Water comes from Big Arm Water System
Big Arm Water System supplies Big Arm: about 95% of residents live in its service area. About 5% 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 116 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 2021–Dec 2023, 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. 083090309.
4 home internet providers serve Big Arm
72% of 145 addresses can get 100/20 Mbps; 41% can get fiber.
| Provider | Technology | Addresses | Fastest (Mbps) |
|---|---|---|---|
| WesternMontanaCommunityTel | Fixed wireless, Fiber | 92% | 100/100 |
| CenturyLink | DSL | 58% | 40/3 |
| T-Mobile | Fixed wireless | 43% | 100/20 |
| Verizon | Fixed wireless | 43% | 300/20 |
FCC National Broadband Map, as of December 2025. Availability as providers report it, not speeds people get.
We don’t have Big Arm’s trash rules yet
Pickup rules, the dump and recycling in Big Arm.
Where your child goes to school
Public school districts and the school path by grade.
Big Arm is in two districts that split the grades: Polson Elementary School District and Polson High School District.
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
Big Arm is unincorporated, so Lake County is the local government.
Election office: FVAP local election office directory, updated Sep 2025; jurisdictions: EAC EAVS 2024. Registration rules and links: vote.gov, updated Nov 18, 2024.
Big Arm spans 2 ZIP codes
ZIP codes where Big Arm residents live, with the share of the town in each.
| ZIP | Post office name | Share of Big Arm | ZIP’s residents in Big Arm |
|---|---|---|---|
| 59910 | Big Arm, MT | 90% | 39% |
| 59860 | Polson, MT | 10% | 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 Big Arm
Who supplies Big Arm’s drinking water, and has it had violations?
Big Arm Water System (EPA ID 083090309). 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 1.0 ppb (Jan 2021–Dec 2023), against a 15 ppb action level.
Who provides electricity in Big Arm?
NorthWestern Energy (NorthWestern Energy LLC - (MT)), an investor-owned utility. Its homes paid about 14.4¢ per kWh in 2025 (EIA).
What internet providers serve Big Arm?
WesternMontanaCommunityTel, CenturyLink, T-Mobile, Verizon (FCC, as of December 2025).
What ZIP codes are in Big Arm?
59910 (90%), 59860 (10%), by share of residents. Census 2020 ZIP Code Tabulation Areas.
What school district is Big Arm in?
Polson Elementary School District and Polson High School District.
How do I register to vote in Big Arm?
Montana has no online registration; you can register in person up to and including Election Day or by mail (postmarked 30 days before). Elections here are run by the Lake County Election Administrator. Check your registration at prodvoterportal.mt.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 Nov 18, 2024 (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.