Complex sentence: Lake Productions, LLC. The lowermost mainstream project--designated the Lower Cumberland Project--was completed in 1966; the dam and the lake it forms were later redesignated Barkley Dam and Lake Barkley in Barkley's honor.
Split into simpler sentences: Lake Productions, LLC. The lowermost mainstream project, the "Lower Cumberland Project," was completed in 1966. The dam and the lake formed by the dam were redesignated Barkley Dam and Lake Barkley in Barkley's honor.