About This Place
Eureka is a city in McPherson County, South Dakota, United States. The population was 868 at the 2010 census.
Eureka is located at 45°46′9″N 99°37′19″W / 45.76917°N 99.62194°W / 45.76917; -99.62194 (45.769069, -99.621953).
According to the United States Census Bureau, the city has a total area of 1.0 square miles (2.6 km²), of which, 0.9 square miles (2.4 km²) of it is land and 0.1 square miles (0.2 km²) of it (7.00%) is water.