The river empties into Lake Erie between Lakewood and Rocky River. Headwaters for the 35-mile East Branch and 36-mile West Branch are in Broadview Heights (Cuyahoga County) and Montville Township (Medina County), respectively. A North Branch rises in Granger Township (Medina County) and flows into the West Branch in Medina. The entire Rocky River Watershed is 294 square miles (188,160 acres) and contains portions of Cuyahoga, Lorain, Medina and Summit counties.