The Hartwell Project, the second in a series of multi-purpose projects planned for the Savannah River Basin, was built between October 1955 and December 1963 at a cost of about $90,000,000. Its concrete dam rises 204 feet above the streambed, and the main dam, including earth fill portions, is 3.37 miles long. At full power, the reservoir stands 660 feet above mean sea level, covers 55,950 acres, and holds enough water to cover 2,549,600 acres to a depth of one foot. The power plant was designed for five generating units; four 66,000-kilowatt units were installed, producing 264,000 kilowatts, enough to supply the needs of a quarter million people, and with a fifth unit the total capacity would be 380,000 kilowatts. For flood control, the project regulates stream flow from a drainage area of 2,086 square miles with an average annual rainfall of more than 62 inches, and 298,00 acre feet above elevation 660 is reserved for controlling floods. For recreation, the reservoir extends about 48 miles up the Tugaloo River and 34 miles up the Seneca River from the dam site, and at full power pool it has a shoreline of 962 miles, with numerous public recreation areas around it, including tent and trailer camps, marinas, launching ramps, scenic overlooks, and picnic areas, while a museum display at the reservoir management office and the powerhouse below the dam are open to the public.