about how many square miles is the mississippi river watershed?
The Mississippi River â Headwaters watershed has approximately 685.05 river miles (NHDPlus - 1:100k source scale, flowline layer) and contains more than 1,000 lakes with a total acreage of 180,375. [[nid:7633]] The Mississippi River - Headwaters watershed consists of 1,255,105 acres (1,961 square miles) in the far north part of the basin. The watershed contains the headwaters of the Mississippi River at Lake Itasca in Itasca State Park.