The Tennessee-Tombigbee Waterway has three main parts. The largest section, from Demopolis, Alabama, north to Amory, Mississippi, uses the Tombigbee River but alters and shortens the existing channel with dams, locks, and short cuts. From Amory, a canal section built with a chain-of-lakes construction extends to the Bay Springs Lock and Dam. The final section cuts deeply through high ground to the Tennessee River. The waterway has a total length of 234 miles, including 149 miles of river section, 46 miles of canal section, and 39 miles of divide cut section. Its standard width is 300 feet, its divide cut width is 280 feet, its minimum channel depth is 9 feet, and its lock dimensions are 110 feet by 600 feet. Construction excavated 307 million cubic yards of material. In lock operation, the upper gates and fill valve are closed while the lower gates are opened so a towboat enters the lock; then the lower gates and drain valve are closed, the fill valve is opened, and the water level in the lock rises; finally the upper gates are opened and the towboat proceeds upstream, with the process reversed for downstream travel.
