Watertown
- County:
- Codington County
- County Seat:
- No
- Area (mi²):
- 18.439
- State:
- South Dakota
Watertown is a city located in Codington County, South Dakota. Watertown has a 2026 population of 23,492. Watertown is currently growing at a rate of 1.22% annually and its population has increased by 3.57% since the most recent census, which recorded a population of 22,683 in 2020.