- Lake Itasca (/aɪˈtæskə/ eye-TASS-kə) is a glacial lake, approximately 4.7 square kilometres (470 hectares; 1,200 acres) in area. It is located in Itasca State Park, in south-eastern Clearwater County, in the Headwaters area of north-central Minnesota, and is the headwater of the Mississippi River. It has a depth range of 20 to 35 feet (5 to 10 m) and is 1,475 feet (450 m) above sea level.