Gillespie
Gillespie is a multi-arch dam located in Maricopa County, Arizona, built in 1921. It carries a Significant hazard potential classification and has a fair condition assessment.
About Gillespie
The primary purpose of Gillespie is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by Gillespie Dam Investments, Llc (private). It impounds the Gila River near Gila Bend.
The dam stands 66 feet tall and stretches 1,768 feet across, creates a reservoir covering 80 acres, has a maximum storage capacity of 3,600 acre-feet, and collects water from a drainage area of 4,965 square miles. Completed in 1921, the structure is over a century old.
This dam has a significant hazard potential classification, meaning that a failure could cause significant economic damage — flooding roads, bridges, or property downstream — but is not expected to result in 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. An emergency action plan is in place for this dam. The most recent inspection on record was 10/25/2023.
At 66 feet, this dam is taller than 96% of all dams in the United States.
Search for dams near your address to see all dams in your area with hazard classifications and safety data.
Location
| State | Arizona |
| County | Maricopa |
| Nearest City | Gila Bend |
| River/Stream | Gila River |
| Coordinates | 33.22944, -112.78306 |
Physical Characteristics
| Dam Type | Multi-Arch |
| NID Height | 66 ft |
| Dam Height | 21 ft |
| Dam Length | 1,768 ft |
| Year Completed | 1921 (105 years old) |
Storage & Hydraulics
| NID Storage | 3,600 acre-ft |
| Max Storage | 3,600 acre-ft |
| Surface Area | 80 acres |
| Drainage Area | 4,965 sq mi |
| Max Discharge | 130,000 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Irrigation |
| Owner | GILLESPIE DAM INVESTMENTS, LLC |
| Owner Type | Private |
| Hazard Classification | Significant |
| Condition Assessment | Fair |
| Last Inspection | 10/25/2023 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | AZ00106 |
| Federal ID | AZ00106 |
| More Info | State Dam Safety Program |