Overview
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.
General
| Project | Salt River |
| Dam Type | Concrete thin arch |
| Location | On the Salt River, 65 miles northeast of Phoenix |
| Longitude | -111.3438 |
| Latitude | 33.5908 |
| Reservoir | Apache Lake |
| Original Construction | 1924-1927 |
| National ID Number | AZ10311 |
| Base Width | 57 ft |
| Watercourse | Salt River |
| Modified Construction | 1936-1937, 1969, 1972 |
Dimensions
| Crest Elevation | 1915 ft |
| Structural Height | 305 ft |
| Crest Length | 660 ft |
| Crest Width | 8 ft |
| Volume of Dam Construction Materials | 162000 cu yd |
| Spillway Crest Elevation | 1891 ft (service); 1869.5 ft (auxiliary) |
| Top Parapet (Elevation) | 1920 ft |
| Hydraulic Height (Normal Operating Depth at Dam) | 266 ft |
Hydraulics & Hydrology
| Spillway Type | Concrete overall structures |
| Auxiliary Spillway | Concrete lined tunnel |
| Total Water Storage at Elevation | 245,138 acre-ft at 1914 |
| Spillway Capacity at Elevation | 150,000 cfs at 1920 |
| Outlet Works Capacity at Elevation | 7,000 cfs at 1914 |
| Drainage Area | 5842 sq mi |
| Maximum Water Surface Elevation | 1919.97 ft |
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