Muddy Creek, formed by the confluence of the 11.2-mile-long (18.0 km)[2] North Branch and the 10.3-mile-long (16.6 km)[2] South Branch at the community of Muddy Creek Forks, flows for 17.2 miles (27.7 km)[3][2] to join the Susquehanna River in the backwater of Conowingo Reservoir.[1]