Big Sand Wash Dam
Big Sand Wash Dam is an earth dam located in Duchesne County, Utah, built in 1968. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Big Sand Wash Dam
The primary purpose of Big Sand Wash Dam is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by Moon Lake Water Users (private). It impounds the Big Sand Wash near Upalco.
The dam stands 142 feet tall and stretches 920 feet across, has a maximum storage capacity of 26,500 acre-feet, and collects water from a drainage area of 26 square miles. Completed in 1968, 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 05/10/2023.
At 142 feet, this dam is taller than 99% of all dams in the United States.
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 Utah 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 | Utah |
| County | Duchesne |
| Nearest City | Upalco |
| River/Stream | Big Sand Wash |
| Coordinates | 40.29519, -110.23071 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 142 ft |
| Dam Length | 920 ft |
| Year Completed | 1968 (58 years old) |
Storage & Hydraulics
| NID Storage | 26,500 acre-ft |
| Max Storage | 26,500 acre-ft |
| Normal Storage | 25,738 acre-ft |
| Drainage Area | 26 sq mi |
| Max Discharge | 595 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Irrigation |
| Owner | MOON LAKE WATER USERS |
| Owner Type | Private |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 05/10/2023 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | UT53326 |
| Federal ID | UT53326 |
| More Info | State Dam Safety Program |