Florence Lake Dam is a concrete multiple-arch dam on the South Fork of the San Joaquin River, in Fresno County, California in the United States. The 171-foot (52 m) high dam was designed by John S. Eastwood and completed in 1926 as part of the Big Creek Hydroelectric Project, an extensive hydroelectric system in the central Sierra Nevada. Its reservoir, Florence Lake, provides for water diversion to Huntington Lake and Big Creek Powerhouses Nos. 1–3 via the 13-mile (21 km) Ward Tunnel.