The Ocmulgee River (ok-MUHL-gee) is a western tributary of the Altamaha River, approximately 255 mi (410 km) long, in the U.S. state of Georgia. It is the westernmost major tributary of the Altamaha. The Ocmulgee River and its tributaries provide drainage for some 6,180 square miles in parts of 33 Georgia counties, a large section of the Piedmont and coastal plain of central Georgia. The name of the river may have come from a Hitchiti words oki ("water") plus molki ("bubbling" or "boiling"), possibly meaning "where the water boils up."