The Safe Harbor Dam is a concrete gravity dam, with an associated hydroelectric power station, on the lower Susquehanna River. It is the most northerly and last of three Great Depression-era public electrification projects' hydroelectric dams, and was constructed between April 1, 1930, and December 7, 1931. It created a long and relatively shallow lake, …The Safe Harbor Dam is a concrete gravity dam, with an associated hydroelectric power station, on the lower Susquehanna River. It is the most northerly and last of three Great Depression-era public electrification projects' hydroelectric dams, and was constructed between April 1, 1930, and December 7, 1931. It created a long and relatively shallow lake, known as Lake Clarke, along the upper stretch of the Conejohela Valley. The creation of the lake shrank the upper Conejohela Flats in size.