Watertown
- Country: United States
- State: South Dakota
- Population: 22,172 (2016)
- Latitude: 44° 54' N (44.89941°)
- Longitude: 97° 6.9' W (-97.11507°)
- Elevation: 528 m/1,732 ft. above sea level
- Time zone: America/Chicago (UTC -06:00); DST observed (UTC -05:00)