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Show Chapter 2 The River and Its Tributaries The Alabama River and its main tributary, the Coosa, form the main stem of the Alabama-Coosa River system, one of the two great river systems which drain to the Gulf of Mexico through the Mo- bile River. Its headwater streams rise along die crest of the Blue Ridge of the Appalachians and flow south and west, becoming the Oostanaula and Etowah Rivers. These unite at Rome to form the Goosa River. The Goosa flows west and southwest for 286 miles through a wide valley bordered by steep hills which sharply constrict the flood plain in places. The stream varies in width from 300 to 500 feet and has numerous rapids and shoals where the river flows over underlying hard rock structures as it descends 450 feet in its course. It enters the Coastal Plain and, just above Montgomery, joins the Tallapoosa River, which drains an extensive Piedmont section in eastern Alabama and western Georgia, to form the Alabama River. The Ala- bama River meanders west, southwest, and south through the Gulf Coastal Plain to its confluence with the Tombigbee River, 45 miles above Mobile Bay. The river system's longest watercourse flows 752 miles. Total fall in the main stem of the river be- tween Rome and the river mouth, a distance of 600 miles3 is 556 feet. Average annual flow of the Alabama River at the mouth is 36,600 cubic feet per second. This is equivalent to 22 inches of runoff from the water- shed as a whole, or 26,850,000 acre-feet annually. Significant variations in flow occur. Flooding has occurred in all months except September, with March the peak flood month. Maximum recorded discharge near the mouth of the Alabama River is 227,000 second-feet. The lowest flow recorded at the same location is 5,320 second-feet. Between 1892 and 1942 there were six extended dry periods, three of which were more than a year long. The power lakes on the Coosa and Tallapoosa Rivers and the Allatoona Reservoir regulate river flow to some extent. The Alabama Power Co. is required to release sufficient water through its power dams to maintain a minimum flow of 6,000 cubic feet per second at Montgomery. This release has provided for satisfactory dilution of waste dis- charged into the river from that city. However, the power company is not required to release more than 5,000 cubic feet a second, nor more than the natural river flow it receives at any given time. In 1941, a low flow of 2,180 second-feet occurred at Mont- gomery because of the low flows above the power installations. 911610-51- 531 |