Oso Largo Dam
Oso Largo Dam is a gravity dam located in Graham County, Arizona, built in 1971. It carries a Low hazard potential classification and has a unsatisfactory condition assessment.
About Oso Largo Dam
The primary purpose of Oso Largo Dam is flood risk reduction. The dam is designed to control downstream flooding by temporarily storing excess water during storms and releasing it at a controlled rate. The dam is owned by Doi Blm (federal). It impounds the Gila River near Fort Thomas, Az.
The dam stands 26 feet tall and stretches 4,625 feet across, creates a reservoir covering 241 acres, has a maximum storage capacity of 616 acre-feet, and collects water from a drainage area of 93 square miles. Completed in 1971, the structure is well into its service life at over 50 years old.
This dam has a low hazard potential classification, meaning that failure would cause minimal damage, limited primarily to the dam owner's property, with no expected loss of life. Its condition is rated unsatisfactory, indicating serious safety deficiencies exist that require immediate attention or remedial action. The most recent inspection on record was 08/20/2010. That was over 15 years ago.
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Location
| State | Arizona |
| County | Graham |
| Nearest City | Fort Thomas, Az |
| River/Stream | Gila River |
| Coordinates | 32.91561, -109.91031 |
Physical Characteristics
| Dam Type | Gravity |
| NID Height | 26 ft |
| Dam Length | 4,625 ft |
| Year Completed | 1971 (55 years old) |
Storage & Hydraulics
| NID Storage | 616 acre-ft |
| Max Storage | 616 acre-ft |
| Normal Storage | 120 acre-ft |
| Surface Area | 241 acres |
| Drainage Area | 93 sq mi |
| Max Discharge | 5,442 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | DOI BLM |
| Owner Type | Federal |
| Hazard Classification | Low |
| Condition Assessment | Unsatisfactory |
| Last Inspection | 08/20/2010 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | AZ20020 |
| Federal ID | AZ20020 |
| More Info | State Dam Safety Program |