Day County is a county in the U.S. state of South Dakota. As of the 2020 census, the population was 5,449. Its county seat is Webster. The county is named for Merritt H. Day, pioneer and 1879 Dakota Territory legislator.
Geography
thumb|right|Native Vegetation based on NRCS soils information
The terrain of Day County consists of rolling hills, partly devoted to agriculture. It is dotted with numerous lakes and ponds, especially its eastern portion. The terrain slopes to the west; its highest point is the northeast corner, at ASL.
The county has a total area of , of which is land and (5.8%) is water.
Lakes
- Amsden
- Antelope
- Bitter
- Blue Dog
- Enemy Swim
- Horseshoe
- Lynn
- Minnewaste
- Pickerel Lake
- Reetz
- Rush
- Sweetwater
- Waubay
Major highways
- 20px U.S. Highway 12
- 20px South Dakota Highway 25
- 20px South Dakota Highway 27
Adjacent counties
- Marshall County – north
- Roberts County – east
- Grant County – southeast
- Codington County – southeast
- Clark County – south
- Spink County – southwest
- Brown County – west
Protected areas
- Buchner Slough State Public Shooting Area
- Holmquist Slough State Public Shooting Area
- Lily State Public Shooting Area
- Myland Pass State Public Shooting Area
- Nelson Slough State Public Shooting Area
- Pickerel Lake State Recreation Area
- Pierpont Lake Recreation Area
- Waubay National Wildlife Refuge