This study of the Savannah River extended from July 1951 into July of 1952. Most of the work was confined to the area just downstream (mile 230.7) from Clark Hill Dam to the river's mouth (mile 0.0). Situated in this reach of the Savannah River is the tract of land that was selected for the Savannah River plant of the Atomic Energy Commission. This tract comprises 250,000 acres in Aiken, Allendale and Barnwell Counties, South Carolina, about 25 miles downstream from Augusta, Georgia. Data were gathered for the most part before the impoundment of the Savannah River by Clark Hill Dam. The principal objectives of the survey were to determine: (a) the water quality characteristics of the stream, (b) the background radioactivity of water and biota and (c) the ecology of the biota and its economic importance before initiation of operations at the Savannah River plant of the Atomic Energy Commission and before impoundment of water by Clark Hill Dam.