Magma Retarding
Magma Retarding is an earth dam located in Pinal County, Arizona, built in 1964. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Magma Retarding
The primary purpose of Magma Retarding 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 Magma Flood Control District (local government). It impounds the Gila River - Tr near Florence.
The dam stands 23 feet tall and stretches 29,290 feet across, creates a reservoir covering 935 acres, has a maximum storage capacity of 18,684 acre-feet, and collects water from a drainage area of 61 square miles. Completed in 1964, the structure is well into its service life at over 50 years old.
This dam carries a high hazard potential classification, which means that a failure or uncontrolled release of water would likely cause loss of human life. This classification reflects the consequences of failure, not the likelihood — it indicates that people live or work in the area downstream. Its condition is rated satisfactory, indicating no existing or potential dam safety deficiencies are recognized. An emergency action plan is in place for this dam. The most recent inspection on record was 01/24/2024.
Living Downstream
If you live or work downstream of this dam, consider taking these steps: learn your local evacuation routes, check whether your county emergency management office has a dam failure inundation map, and sign up for local emergency alerts. The Arizona dam safety program can provide more specific information about emergency planning for this structure.
Search for dams near your address to see all dams in your area with hazard classifications and safety data.
Location
| State | Arizona |
| County | Pinal |
| Nearest City | Florence |
| River/Stream | Gila River - Tr |
| Coordinates | 33.12083, -111.38806 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 23 ft |
| Dam Height | 23 ft |
| Dam Length | 29,290 ft |
| Year Completed | 1964 (62 years old) |
Storage & Hydraulics
| NID Storage | 18,684 acre-ft |
| Max Storage | 18,684 acre-ft |
| Normal Storage | 5,610 acre-ft |
| Surface Area | 935 acres |
| Drainage Area | 61 sq mi |
| Max Discharge | 1,000 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | MAGMA FLOOD CONTROL DISTRICT |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 01/24/2024 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | AZ00083 |
| Federal ID | AZ00083 |
| More Info | State Dam Safety Program |