Ponca Creek is a stream that flows from southern South Dakota and into northern Nebraska. It is 139 miles (224 km) long. Its source is about 4 miles (6.4 km) west of U.S. 183, near Colome. It flows into the Missouri River 6 miles (9.7 km) northwest of Niobrara. Ponca Creek starts out going east, then takes a southeast direction, which continues until around Bristow, Nebraska, where it turns east again until it flows into the Missouri River. The entire Ponca Creek watershed drains 520,000 acres (2,100 km2). The watershed stretches from central Tripp County to central Gregory County.