Onaka
- County:
- Faulk County
- County Seat:
- No
- Area (mi²):
- 0.259
- State:
- South Dakota
Onaka is a town located in Faulk County, South Dakota. Onaka has a 2025 population of 15. Onaka is currently declining at a rate of 0% annually and its population has increased by 7.14% since the most recent census, which recorded a population of 14 in 2020.
The median age in Onaka is 13.5 years: 35.8 years for males, and 1.9 years for females.