Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. WAseca County is a county located in the U.S. State of Minnesota. AS of 2000, the population was 19,526. ITs county seat is Waseca. ACcording to the U.S. CEnsus Bureau, the county has a total area of 433 square miles (1,121 km²), of which 423 square miles (1,096 km²) is land and 10 square miles (25 km²) (2.21%) is water. THe Le Sueur River flows through a part of the county.AS of the census of 2000, there were 19,526 people, 7,059 households, and 4,990 families residing in the county. THe population density was 46 people per square mile (18/km²).