The South River is part of the Upper Ocmulgee River watershed and is approximately 60 miles long. The main South River tributary emerges into daylight just north of Hartsfield-Jackson International Airport along busy Norman Berry Drive in the city of East Point. From this point, it flows north for a short distance before turning southeast. It is piped under Interstate 75/85S about at the point where the Interstate highway splits; I-75S heads to Macon and I-85S to Montgomery. The river emerges on the southeast side of the city of Atlanta and from this point remains day-lighted (visible) for the entire journey to Jackson Lake Reservoir traversing six counties - DeKalb, Rockdale, Henry, Newton, Butts, and Jasper – along its route.
The South River watershed drains the entire southeast section of Atlanta which means that many of the river's creek tributaries literally crawl underground through the city’s combined sewage and stormwater system. Using the Georgia State Capitol as a reference point, rain that falls on the side of the Capitol that faces east (back) travels to the South River while rains that falls on the side of the Capitol that faces west (front) flows to the Chattahoochee River. The South, Yellow, Alcovy, and Tussahaw Rivers converge in Jasper County to form Jackson Lake Reservoir. Water flowing out of the reservoir is augmented along the way by tributaries and becomes the Ocmulgee River. Near Macon the Ocmulgee and Oconee Rivers join to form the mighty Altamaha River which flows into the Atlantic Ocean near Darien about 50 miles south of Savannah.
A watershed is the area of land where all of the water that is under it or drains off of it goes into the same place. In south DeKalb County, that “same place” is South River. The graphic below shows how a watershed works.
The quality of water in South River is determined by the number and types of activities that take place in the watershed. Human activities that pollute creeks and streams will eventually pollute the river. Today, pollution from combined sewer overflows, sanitary sewage overflows, untreated and uncontrolled stormwater runoff, and inadequately maintained residential septic systems are the greatest threat to the watershed.