Codington County is a county in the U.S. state of South Dakota. As of the 2020 census, the population was 28,325, making it the 7th most populous county in South Dakota. Its county seat is Watertown. The county was created in 1877 and organized in 1878. It is named for Rev. George S. S. Codington, Dakota Territory legislator.

Watertown is a city in and the county seat of Codington County, South Dakota, United States. Watertown is home to the Redlin Art Center, which houses many of the works of Terry Redlin, one of the nation's most popular wildlife artists. Watertown is between Pelican Lake and Lake Kampeska, from which Redlin derived inspiration for his artwork.