Coolidge Dam

Picture of Coolidge Dam



  • Dam type: Reinforced concrete multiple dome and buttress, similar to multiple arch and buttress
  • Location: 31 miles east of Globe, Arizona
  • Watercourse: Gila River
  • Reservoir: San Carlos
  • Original construction: 1924-28
  • Modified: 1992-94



  • Total storage to El. 2511: 910,000 acre-ft
  • Hydraulic height: 220 ft
  • Total spillway capacity at El. 2557: 295,170 cfs
  • Dam crest capacity at El. 2557: 163,590 cfs
  • Outlet works capacity at El. 2511: 5,000 cfs


  • Drainage area: 12,870 sq mi
  • HMR: N/A
  • PMF: 1987 Summer Type
  • Volume: 2,143,000 acre-ft over 17 days
  • Peak inflow: 800,000 cfs
  • Maximum water surface: 2557 ft


  • Foundation: Precumbrian granite is most widely exposed unit. Ten rock units have been identified along with faults in the dam site.

Dynamic Loads


Coolidge Dam is a multiple-dome concrete structure. The dam was designed and constructed, and is owned and operated, by the Bureau of Indian Affairs (BIA), and was completed in 1928. The dam consists of three domes, which are supported by massive buttresses on 100-foot centers. Two uncontrolled ogee crest spillways are concrete lined and located on each abutment.

In 1990 the BIA requested that the Bureau of Reclamation mitigate an identified safety of dams issue associated with the probable maximum flood overtopping and failing the dam. The modification included a stability buttress placed on the left abutment and overtopping protection placed on both abutments. Of note, this overtopping protection consisted of concrete blocks placed with joints at 20-foot centers each way and with a 2.5-foot minimum thickness. Reinforcement was placed in the top face of the blocks and extends through the joints. Waterstops were placed in all of the joints and anchor bars and drains were constructed in each placement; armor-stone was added in the channel to prevent popping (hydraulic jacking) and eroding of rock immediately downstream of the dam; and concrete lining was placed on the floors of both spillways to prevent erosion of the existing deteriorated concrete. These modifications were made between 1992 and 1994.


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| 1992 Satelite image of Coolidge Dam |

Last Modified:
Bureau of Reclamation, Department of the Interior