Long before Lake Jocassee existed, the Blue Ridge Escarpment around today's reservoir was a network of Cherokee places, river valleys and mountain communities. SCDNR's Jocassee Gorges history notes that names such as Jocassee, Keowee, Toxaway, Eastatoee and Oconee reflect the region's Native American history. The old Vale of Jocassee lay near the meeting of the Toxaway and Whitewater rivers; homes, roads, farms and community sites from the valley now lie beneath the reservoir.
The landscape changed repeatedly before the lake was built. A catastrophic 1916 failure of the Toxaway Dam in North Carolina sent flooding down the Toxaway River and damaged farmland. Timber became a major industry, and Poinsett Lumber Company, a Singer Sewing Machine subsidiary, controlled large tracts beginning around 1939. In 1963 Duke Power formed Carolina Land and Timber Company and acquired a large Horsepasture-area tract; Duke announced the Keowee-Toxaway Project in 1965 and began development in 1967.
The Keowee-Toxaway Project created both Lake Keowee and Lake Jocassee. SCDNR identifies Jocassee as a Duke Energy reservoir impounding the Whitewater, Thompson, Toxaway and Horsepasture rivers and dates the modern lake/pumped-storage facility to 1973. The larger engineering complex later received major recognition: Duke notes that the Keowee-Toxaway Project was selected in 1975 for an American Society of Civil Engineers award recognizing outstanding civil-engineering achievement.
The modern story is also one of conservation. Lake Jocassee is bordered by a large expanse of protected mountain land, and the state acquired the Jocassee Gorges property in 1998 to protect its unusual biology and recreational resources. Today the reservoir is both working energy infrastructure and the centerpiece of one of South Carolina's most distinctive mountain landscapes, with deep cold water, waterfalls, trout fisheries and the only public lake access at Devils Fork State Park.