Kentucky Dam, the lowermost and the largest of the multiple-purpose projects of the Tennessee River system, is the key to effective control of discharges from the Tennessee, the largest tributary of the Ohio River. Located at river mile 22.4, Kentucky Dam is only 67.4 river-miles above Cairo, Illinois, and its large reservoir with more than 4,000,000 acre-feet of flood storage capacity occupies as strategic position for the reduction of flood crests on the lower Ohio and Mississippi Rivers. The navigation lock at this project forms the lower gateway to the 184-mile long Kentucky Reservoir, one of a chain of nine reservoirs extending a year-round 9-foot navigation channel more than 600 miles to Knoxville, Tennessee, and connects this system of reservoirs to the major inland waterways of the great central Mississippi Valley with outlets for navigation to the Great Lakes and the Gulf of Mexico.