Barkley Dam was created on the Cumberland River, only a couple of miles from Kentucky Dam. The dam was created for several purposes, but most importantly, flood control and to generate hydroelectric power. Eddyville and Kuttawa, located on the Cumberland River, were both flooded by the river often. The US Army Corps of Engineers decided that the small locks and dams up and down the Cumberland weren't enough for flood control, so the construction of Barkley Dam began in 1959 and completed five years later.
Two major communities were relocated when Lake Barkley was built in the 1960s. Kuttawa and Eddyville, with a combined population of 3500, were about to be flooded permanently. Eddyville in particular was completely relocated to its present location on US 62/641. A striking characteristic of Eddyville today is that none of the buildings there were built prior to the 1960s.
Before that time, the present location of Eddyville was just a big field. Lake Barkley is somewhat young, only about 50 years old, unlike Kentucky Lake's age of over 70 years. One of the neat things about Lake Barkley is that you can still see old foundations, sidewalks, and streets of Old Eddyville during Barkley's winter pool (when the lake is five feet lower).
Just like Kentucky Lake, the creation of Lake Barkley forced the re-routing of several roads including US 62, US 68, Kentucky 80, Kentucky 93, and several others. And just like with Kentucky Lake, the Illinois Central Railroad was relocated, which you can still see under water from high above.