Horse Mesa Dam


Located on the Salt River 65 miles northeast of Phoenix, Horse Mesa Dam is a concrete thin-arch structure 305 feet high. Constructed by the Salt River Valley Water Users' Association between 1924-1927, the dam contains 162,000 cubic yards of concrete, and forms a 245,138 acre-foot reservoir.

The spillway, as modified in 1936-1937 by the Bureau of Reclamation, includes a 50,000 cubic foot per second, concrete-lined auxiliary tunnel, 30 feet in diameter and 400 feet long; a regulating gate, gatehouse, and operating mechanism for controlling the tunnel; and a concrete discharge apron below the existing spillway. The piers on the radial-gate spillways were thickened, individual motor-driven gate hoists were installed, and two 15-kilovolt-ampere gasoline-engine driven generators were installed for emergency operation of the hoist motors.

RegionFacilities in Lower Colorado | Lower Colorado Home Page
ProjectSalt River
Dam TypeConcrete thin arch
ReservoirApache Lake
WatercourseSalt River
LocationOn the Salt River, 65 miles northeast of Phoenix
Original Construction1924-1927
Modified Construction1936-1937, 1969, 1972
National ID NumberAZ10311
Hydrologic Unit Code

Structural Height305 ft
Hydraulic Height (Normal Operating Depth at Dam)266 ft
Top Parapet (Elevation)1920 ft
Spillway Crest Elevation1891 ft (service); 1869.5 ft (auxiliary)
Crest Elevation1915 ft
Crest Length660 ft
Crest Width8 ft
Base Width57 ft
Volume of Dam Construction Materials162000 cu yd
Streambed at Dam Axis
Top of Exclusive Flood Control Pool (Elevation)
Top of Joint Use Pool (Elevation)
Top of Active Conservation Pool (Elevation)
Top of Inactive Conservation Pool (Elevation)
Top of Dead Storage Pool (Elevation)

Hydraulics & Hydrology
Total Water Storage at Elevation245,138 acre-ft at 1914
Maximum Water Surface Elevation1919.97 ft
Normal Water Surface Elevation
Spillway Type Concrete overall structures
Spillway Capacity at Elevation150,000 cfs at 1920
Auxiliary Spillway Concrete lined tunnel
Auxiliary Spillway Capacity at Elevation
Uncontrolled Spillway Capacity at Elevation
Outlet Works Capacity at Elevation 7,000 cfs at 1914
Diversion Capacity at Elevation
Drainage Area5842 sq mi
Hydrometeorological Report (HMR)
Probable Maximum Flood (PMF) Report1986 Winter Type

Contact Information
TitleArea Office Manager
OrganizationPhoenix Area Office
Address6150 West Thunderbird Road
CityGlendale, AZ 85306-6200
Phone (Fax)623 773-6480
Phone (Office)623 773-6200
OrganizationArea Office Manager
AddressPhoenix Area Office
CityPhoenix, AZ 85306-6200
Phone (Office)623 773-6200

Last updated: Jun 29, 2009