Illinois River watershed
The Illinois River watershed stretched from the Illinois border in northwest Indiana and up into Michigan in St. Joseph County.
This drainage area include most of the state known as the Lake Region, including the city of La Porte but excluding the area around the Indiana Dunes and the Grand Calumet River, which drains into Lake Michigan.
Lake Michigan watersheds
There are two watersheds in the state that drain into Lake Michigan. In the northwest part of the state, it includes the Grand Calumet River area in Lake and Porter counties and includes the cities of Gary and Hammond, which includes the cities of .
The second, and larger Lake Michigan watershed lies in the north central and northeastern part of the state. It includes the cities of South Bend, Elkhart, Mishawaka and Goshen.
Maumee River watershed
The smallest watershed in the state is the Maumee River watershed in the northeast part of the state on the border with Ohio. It includes most of the city of Fort Wayne as well as the cities of New Haven and Auburn. The Maumee eventually empties into Lake Erie at Toledo, Ohio.
Ohio River watershed
The Ohio River watershed includes the extreme southern part of the state as well as the extreme southwestern Indiana counties. This drainage area includes the cities of Evansville, Richmond and New Albany as well as the Indiana suburbs of Cincinnati, Ohio.
Wabash River watershed
By far the largest watershed in the state, the Wabash River drainage area contains the several large cities, including Indianapolis and the extreme western part of Fort Wayne. Other cities included in the area are Bloomington, Muncie, Lafayette, Anderson and Terre Haute. This watershed also includes most of Indiana's prime farm land.