Buffalo Creek is a tributary of the West Branch Susquehanna River in Union County, Pennsylvania, in the United States. It is approximately 28.5 miles (45.9 km) long and flows through Hartley Township, Lewis Township, West Buffalo Township, Mifflinburg, Buffalo Township, Kelly Township, and Lewisburg. Its watershed has an area of 134 square miles (350 km2). It is in the ridge-and-valley province of the Appalachian Mountains. Some streams and parts of streams in the creek's watershed are high-quality cold-water fisheries. There are ten types of rock formations and eight types of soil series in the watershed. The forests in the Buffalo Creek watershed are mostly deciduous hardwood, hemlock, and pine.