The Altamaha River is a major river in the U.S. state of Georgia. It flows generally eastward for 137 miles (220 km) from its origin at the confluence of the Oconee River and Ocmulgee River towards the Atlantic Ocean, where it empties into the ocean near Brunswick, Georgia. There are no dams directly on the Altamaha, though there are some on the Oconee and the Ocmulgee. Including its tributaries, the Altamaha River's drainage basin is about in size, qualifying it among the larger river basins of the US Atlantic coast. It is reportedly the third largest contributor of fresh water to the Atlantic Ocean from North America. Including its longest tributary (the Ocmulgee River) in length calculations as is standard USGS practice, its length of places it seventh on the list of U.S. rivers entirely within one state, behind only four Alaskan rivers, the Sacramento-Pit River in California, and the Trinity River in Texas. The beginning of the Colorado River of Texas is just within New Mexico. The long Mobile-Alabama-Coosa River system, mostly in Alabama, originates a short distance within Georgia.