High Quality Content by WIKIPEDIA articles! The Cahaba River is the longest free-flowing river in Alabama and is among the most scenic and biologically diverse rivers in the United States. The Cahaba River is a major tributary of the Alabama River and part of the larger Mobile River Basin. With headwaters near Birmingham, the Cahaba meanders to the southwest, then at Heiberger turns southeast and joins the Alabama River at Cahaba, in Dallas County. Contained entirely within central Alabama, the Cahaba River is 194 miles (312 km) long and drains an area of 1,870 square miles (4,800 km2).