The Presumpscott River is one of Maine's largest rivers. It is 25.8 miles long. Flowing from Sebago Lake to the sea at Casco Bay, it is the main outlet of Sebago Lake. It naturally divides the towns of Gorham and Windham.

The river provided an early transportation corridor and reliable water power for industrial development.

A series of dams and locks were completed in 1830 to form the Cumberland and Oxford Canal. Read about the Cumberland and Oxford