Mahanoy Creek is a 51.6-mile-long (83.0 km) tributary of the Susquehanna River in Northumberland and Schuylkill counties, Pennsylvania. There are at least 35 sources of acid mine drainage in the creek's watershed. Anthracite was mined in the upper part of the Mahanoy Creek watershed in the 19th and 20th centuries. Mahanoy Creek's tributaries include Schwaben Creek, Zerbe Run, Little Mahanoy Creek, Shenandoah Creek, and North Mahanoy Creek. Little Mahanoy Creek and Schwaben Creek are two streams in the watershed that are unaffected by acid mine drainage. Schwaben Creek has a higher number and diversity of fish species than the main stem.