Horse Mesa Dam

Horse Mesa Dam
Country	United States
Location	Tonto National Forest, Maricopa County, Arizona
Coordinates	33°35′27″N 111°20′38″W
Construction began	1924
Opening date	1927
Owner(s)	U.S. Bureau of Reclamation
Operator(s)	Salt River Project
Dam and spillways
Type of dam	Concrete thin arch
Impounds	Salt River
Height	305 ft (93 m)
Length	660 ft (200 m)
Width (crest)	8 ft (2.4 m)
Width (base)	57 ft (17 m)
Dam volume	162,000 cu yd (124,000 m3)
Spillways	Gated concrete tunnel and over-the-crest
Spillway capacity	150,000 cu ft/s (4,200 m3/s)
Reservoir
Creates	Apache Lake
Total capacity	245,138 acre⋅ft (0.302373 km3)
Catchment area	5,842 sq mi (15,130 km2)
Surface area	2,656 acres (1,075 ha)
Normal elevation	1,919 ft (585 m)
Power Station
Turbines	3x 112/3MW units, 1x 97MW pumped-storage unit
Installed 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 660 feet (200 m) long, 300 feet (91 m) 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 2,067 feet (630 m) 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.

Downstream view of Horse Mesa Dam.

Water flowing out of a spillway at Horse Mesa, circa 1940

Salt River below the dam.

External links

• SRP Horse Mesa Dam
• Historic American Engineering Record (HAER) No. AZ-15, "Horse Mesa Dam, Salt River, 65 miles East of Phoenix, Phoenix vicinity, Maricopa County, AZ"