Lake County, South Dakota

Lake County
Lake County Courthouse
Location within the U.S. state of South Dakota
South Dakota's location within the U.S.
Coordinates: 44°01′N 97°07′W / 44.02°N 97.12°W / 44.02; -97.12
Country United States
State South Dakota
Founded1873
SeatMadison
Largest cityMadison
Area
  Total
575 sq mi (1,490 km2)
  Land563 sq mi (1,460 km2)
  Water12 sq mi (30 km2)  2.1%
Population
 (2020)
  Total
11,059
  Estimate 
(2024)
11,006
  Density19/sq mi (7.4/km2)
Time zoneUTC−6 (Central)
  Summer (DST)UTC−5 (CDT)
Congressional districtAt-large
Websitewww.lake.sd.gov

Lake County is a county in the U.S. state of South Dakota. As of the 2020 census, the population was 11,059. Its county seat is Madison. The county was formed in 1873.