Hesperus Wash (no. 36)
Hesperus Wash (no. 36) is an earth dam located in Maricopa County, Arizona, built in 1973. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Hesperus Wash (no. 36)
The primary purpose of Hesperus Wash (no. 36) 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 Town Of Fountain Hills (local government). It impounds the Verde River - Tr near Fountain Hills.
The dam stands 49 feet tall and stretches 1,060 feet across, creates a reservoir covering 28 acres, has a maximum storage capacity of 482 acre-feet, and collects water from a drainage area of 2 square miles. Completed in 1973, 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 02/14/2024.
At 49 feet, this dam is taller than 92% 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 | Maricopa |
| Nearest City | Fountain Hills |
| River/Stream | Verde River - Tr |
| Coordinates | 33.63667, -111.74667 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 49 ft |
| Dam Height | 36 ft |
| Dam Length | 1,060 ft |
| Year Completed | 1973 (53 years old) |
Storage & Hydraulics
| NID Storage | 482 acre-ft |
| Max Storage | 482 acre-ft |
| Normal Storage | 280 acre-ft |
| Surface Area | 28 acres |
| Drainage Area | 2 sq mi |
| Max Discharge | 11,800 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | TOWN OF FOUNTAIN HILLS |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 02/14/2024 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | AZ00074 |
| Federal ID | AZ00074 |
| More Info | State Dam Safety Program |