The Big River basin is located in east-central Missouri and drains 955 square miles of the Ozark plateau in portions of six counties. Big River has eight, order five tributaries and flows northward for 138 miles until it reaches the Meramec River.
The majority of basin land use is forest and pasture with some row cropping along stream bottoms. However, urbanization is rapidly increasing in the lower basin. Only 5% of the basin is owned by state and federal agencies. Surveys have found that local-users spend much time recreating (especially fishing) on and around Big River.