Spring Valley is a city in Fillmore County, Minnesota, United States. The population was 2,479 at the 2010 census. Spring Valley was laid out …Spring Valley is a city in Fillmore County, Minnesota, United States. The population was 2,479 at the 2010 census. Spring Valley was laid out in 1855, and named for a spring near the town site. A post office has been in operation at Spring Valley since 1855. Spring Valley was incorporated in 1872.