Powerline
Powerline is an earth dam located in Pinal County, Arizona, built in 1967. It carries a High hazard potential classification and has a fair condition assessment.
About Powerline
The primary purpose of Powerline 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 Flood Control District Of Maricopa County (local government). It impounds the Magma Wash near Mesa / Apache Junction.
The dam stands 42 feet tall and stretches 13,398 feet across, creates a reservoir covering 456 acres, has a maximum storage capacity of 5,100 acre-feet, and collects water from a drainage area of 61 square miles. Completed in 1967, 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 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 01/22/2024.
At 42 feet, this dam is taller than 89% of dams nationwide.
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 | Mesa / Apache Junction |
| River/Stream | Magma Wash |
| Coordinates | 33.36161, -111.55087 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 42 ft |
| Dam Height | 32 ft |
| Dam Length | 13,398 ft |
| Year Completed | 1967 (59 years old) |
Storage & Hydraulics
| NID Storage | 5,100 acre-ft |
| Max Storage | 5,100 acre-ft |
| Normal Storage | 4,194 acre-ft |
| Surface Area | 456 acres |
| Drainage Area | 61 sq mi |
| Max Discharge | 25,000 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | FLOOD CONTROL DISTRICT OF MARICOPA COUNTY |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Fair |
| Last Inspection | 01/22/2024 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | AZ00082 |
| Federal ID | AZ00082 |
| More Info | State Dam Safety Program |