Grayhorse Detention Dam
Grayhorse Detention Dam is a gravity dam located in Greenlee County, Arizona, built in 1956. It carries a Low hazard potential classification and has a fair condition assessment.
About Grayhorse Detention Dam
The primary purpose of Grayhorse Detention 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 Round Mountain Draw Tributary near Duncan, Az.
The dam stands 28 feet tall and stretches 603 feet across, creates a reservoir covering 20 acres, and has a maximum storage capacity of 120 acre-feet. Completed in 1956, 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 fair — the dam has minor deficiencies that are being addressed or do not pose an immediate safety threat. The most recent inspection on record was 08/12/2015. That was over 10 years ago.
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Location
| State | Arizona |
| County | Greenlee |
| Nearest City | Duncan, Az |
| River/Stream | Round Mountain Draw Tributary |
| Coordinates | 32.54085, -109.07489 |
Physical Characteristics
| Dam Type | Gravity |
| NID Height | 28 ft |
| Dam Length | 603 ft |
| Year Completed | 1956 (70 years old) |
Storage & Hydraulics
| NID Storage | 120 acre-ft |
| Max Storage | 120 acre-ft |
| Normal Storage | 100 acre-ft |
| Surface Area | 20 acres |
| Max Discharge | 890 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | DOI BLM |
| Owner Type | Federal |
| Hazard Classification | Low |
| Condition Assessment | Fair |
| Last Inspection | 08/12/2015 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | AZ20012 |
| Federal ID | AZ20012 |
| More Info | State Dam Safety Program |