| Horse Mesa Dam | |
| Coordinates: | 33.5908°N -111.3439°W |
| Country: | United States |
| Location: | Tonto National Forest, Maricopa County, Arizona |
| Construction Began: | 1924 |
| Opening: | 1927 |
| Owner: | U.S. Bureau of Reclamation |
| Operator: | Salt River Project |
| Dam Type: | Concrete thin arch |
| Dam Height: | 305feet |
| Dam Length: | 660feet |
| Dam Width Crest: | 8feet |
| Dam Width Base: | 57feet |
| Dam Volume: | 162000yd3 |
| Dam Crosses: | Salt River |
| Spillway Count: | Gated concrete tunnel and over-the-crest |
| Spillway Capacity: | 150000cuft/s |
| Res Name: | Apache Lake |
| Res Capacity Total: | 245138acre feet |
| Res Catchment: | 5842mi2 |
| Res Surface: | 2656acres |
| Res Elevation: | 1919feet |
| Plant Turbines: | 3x 112/3MW units, 1x 97MW pumped-storage unit |
| Plant Capacity: | 129 MW |
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 660feet long, 300feet 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.[1] It has an estimated elevation of 2067feet above sea level.
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.