The Horse Mesa Dam is a concrete thin arch dam located in the Superstition Mountains, northeast of Phoenix in Maricopa County, Arizona. The dam is 660 ft long, 300 ft high and was built between 1924 and 1927. The dam includes three conventional hydroelectric generating units totaling 32 megawatts (MW) and a pumped-storage unit with a capacity of 97 MW. The dam and associated infrastructure were listed on the National Register of Historic Places in 2017. A few homes are nearby for temporary employee housing. Its name is derived from when sheep-herders used to graze their saddle and pack animals on the mesa when they were driving their flocks through the area. It has an estimated elevation of 2067 ft above sea level.

Reservoir

The dam forms Apache Lake as it impounds the Salt River. The dam and reservoir are located downstream from the Theodore Roosevelt Dam, and upstream from the Mormon Flat Dam.