The Olentangy River Watershed consists of 88.5 miles of the Olentangy River and the surrounding 565 square-mile area drained by the river and its network of tributary streams. The river has its source in highlands in the southwest corner of Richland County at an elevation of 1189 feet above sea level. It has an average gradient of 5.5 feet / mile as it flows south to its confluence with the Scioto River in Columbus in Franklin County (elevation = 702 feet). The watershed itself is part of the larger Scioto River Basin that drains south to the Ohio River. A distinctive feature of the rivers in central Ohio, especially in Franklin and Delaware counties, is the peculiar, sub-parallel, nearly straight, north-south trend of four of the five major streams: the Scioto River, the Olentangy River, Alum Creek, and Big Walnut Creek.