Altamaha River

The third largest contributor of freshwater to the Atlantic Ocean on North America's eastern shore, the Altamaha River basin lies entirely within the state of Georgia.

The Altamaha River, formed by the confluence of the Ocmulgee and Oconee rivers near Lumber City and joined farther downstream by the Ohoopee River, flows more than 130 straight-line miles from its northernmost points to its entry into the Atlantic Ocean north of Brunswick. The Altamaha River basin drains nearly one quarter of the state of Georgia, with its 14,000-square-mile watershed reaching from the upper Piedmont to the Lower Coastal Plain and encompassing the cities of Athens, Macon, Milledgeville, and parts of Atlanta.

The river and its floodplain swamps and marshes are among the most undisturbed habitats in the state, although increasing population in the Coastal Plain and pressure from development are threatening their pristine nature. The integrity of the lower river's ecosystem can be credited in part to the absence of dams: the banks of the river as it courses through the Coastal Plain are so low-lying and broad that the river is relatively inaccessible to humans.

The Altamaha flows into the Atlantic Ocean near Darien, about midway down Georgia's coastline, carrying millions of gallons of freshwater, nutrients, and sediments to the estuary and coastal area every day. This estuary, where the freshwater from the river mixes with saltwater from the Atlantic, occupies an area of roughly twenty-six square miles in Glynn and McIntosh counties in southeastern Georgia and is arguably the largest intact, relatively undegraded estuary system on the Atlantic coast.