river formed southeast of Tallulah Falls, Ga., U.S., at the confluence of the Chattooga and Tallulah rivers (which are there dammed to form Tugaloo and Yonah lakes). The river then flows southeast, serving as a portion of the Georgia–South Carolina state boundary. After a course of 45 miles (72 km), the Tugaloo joins the Seneca River to form the Savannah River, which in its upper course is called the Keowee. The name Tugaloo probably derives from an early Cherokee settlement called Dugiluyi, referring to the forks of a stream.