Nickajack Dam is a hydroelectric dam in Marion County in the U.S. state of Tennessee. It is one of nine dams on the Tennessee River owned and operated by the Tennessee Valley Authority, which built the dam in the mid-1960s to replace the outdated Hales Bar Dam upstream. The dam impounds the Nickajack Lake and feeds into Guntersville Lake. Nickajack Dam is named for a Cherokee village once located just upstream from the dam (the site is now submerged). The village was the namesake for Nickajack Cave, which was partially flooded by the reservoir. Location Nickajack Dam is located above the mouth of the Tennessee River, near the point where the states of Tennessee, Georgia, and Alabama meet. This stretch of the river marks a region where the river begins to exit the once treacherous Tennessee River Gorge en route to the flatlands around Guntersville, Alabama. The Sequatchie River empties into the dam's tailwaters, and the city of South Pittsburg is just over downstream from the dam. Nickajack Lake stretches northeast for over , all the way to the base of Chickamauga Dam in Chattanooga. Tennessee State Highway 156 passes just south of Nickajack Dam, and Interstate 24 passes a few miles to the north. Capacity Nickajack Dam is high and long. Its reservoir has of shoreline and of water surface. The dam's 10 spillway bays have a combined discharge of . The electrical generating capacity of Nickajack is 104 megawatts. Nickajack is serviced by a auxiliary lock that can lift or lower as many as nine large barges at a time between Guntersville Lake and Nickajack Lake. The dam's original design allowed for an main lock beside the auxiliary, but it was never completed. This lock, as well as every lock on the Tennessee River, is operated and maintained by the U.S. Army Corps of Engineers. Background and construction Before the completion of Hales Bar Dam in 1913, the Tennessee River Gorge was one of the major impediments— along with Muscle Shoals and the Elk River shoals— to year-round navigation on the Tennessee River. Along with unpredictable water levels, the gorge was filled with numerous water hazards, some of which had been given nicknames such as "The Suck", "The Skillet", and "The Pan." In the early 1900s, the U.S. Army Corps of Engineers realized that a dam near the southwestern end of the gorge would flood the water hazards