Buena Vista County is a county located in the U.S. state of Iowa. As of the 2020 census, the population was 20,823. Its county seat is Storm Lake. The county is named for the final victory of Field General Zachary Taylor in the Mexican–American War.

Storm Lake is a city in and the county seat of Buena Vista County, Iowa, United States. The population was 11,269 in the 2020 census, an increase from 10,076 in the 2000 census. Located along the northern shore of the Storm Lake reservoir, the city is home to Buena Vista University, King's Pointe Waterpark Resort, the Living Heritage Tree Museum, and the Santa's Castle holiday attraction. It is the principal city of the Storm Lake micropolitan area.