Living in Hamlin Township, SD: what to set up and who to call
Hamlin Township spans 4 ZIP codes; 57223 holds the most residents (67%). Hamlin-Codington Regional Library, 12.3 miles away, is the closest library to Hamlin Township.
I’m new in town
What to set up in Hamlin 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 Hamlin Township.
Power comes from NorthWestern Energy
NorthWestern Energy (NorthWestern Energy - (SD)), an investor-owned utility, serves all of Hamlin Township. Its homes paid an average of 13.3¢ per kWh in 2025, about $125 a month (its average across South Dakota).
Start or move service: northwesternenergy.com · (800) 245-6977
Service territory: HIFLD Electric Retail Service Territories (map dated Aug 2023). Prices and customers: EIA-861, 2025.
Water comes from Sioux Rural Water System
Sioux Rural Water System supplies almost all of Hamlin Township. It draws ground water and serves 4,280 people in all.
No health-based violations reported to EPA in the five years to October 2026, like 80% of the 5,012 systems serving 3,301–10,000 people.
The latest lead result on file, the 90th percentile of homes sampled in Jan–Dec 2025, was 4.0 ppb, below the 15 ppb action level that applied. That’s higher than 87% 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. SD4600866.
5 home internet providers serve Hamlin Township
100% of 101 addresses can get 100/20 Mbps; 100% can get fiber.
| Provider | Technology | Addresses | Fastest (Mbps) |
|---|---|---|---|
| ITC | Fiber | 100% | 1,000/1,000 |
| CenturyLink | DSL | 3% | 10/1 |
| T-Mobile | Fixed wireless | 44% | 100/20 |
| GigFire | Fixed wireless | 39% | 150/130 |
| Midco | Fixed wireless | 25% | 100/20 |
FCC National Broadband Map, as of December 2025. Availability as providers report it, not speeds people get.
We don’t have Hamlin Township’s trash rules yet
Pickup rules, the dump and recycling in Hamlin Township.
Where your child goes to school
Public school districts and the school path by grade.
Most of Hamlin Township (99%) is in Castlewood School District 28-1.
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.
Hamlin Township spans 4 ZIP codes
ZIP codes where Hamlin Township residents live, with the share of the town in each.
| ZIP | Post office name | Share of Hamlin Township | ZIP’s residents in Hamlin Township |
|---|---|---|---|
| 57223 | Castlewood, SD | 67% | 12% |
| 57226 | Clear Lake, SD | 21% | 3% |
| 57238 | Goodwin, SD | 9% | 5% |
| 57201 | Watertown, 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 Hamlin Township
Who supplies Hamlin Township’s drinking water, and has it had violations?
Sioux Rural Water System (EPA ID SD4600866). It reported no health-based violations to EPA in the five years to October 2026; 80% of systems its size had none. Its latest lead 90th percentile was 4.0 ppb (Jan–Dec 2025), against a 15 ppb action level.
Who provides electricity in Hamlin Township?
NorthWestern Energy (NorthWestern Energy - (SD)), an investor-owned utility. Its homes paid about 13.3¢ per kWh in 2025 (EIA).
What internet providers serve Hamlin Township?
ITC, CenturyLink, T-Mobile, GigFire, Midco (FCC, as of December 2025).
What ZIP codes are in Hamlin Township?
57223 (67%), 57226 (21%), 57238 (9%), 57201 (3%), by share of residents. Census 2020 ZIP Code Tabulation Areas.
What school district is Hamlin Township in?
Castlewood School District 28-1.
How do I register to vote in Hamlin 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 Hamlin 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.