Upper Stillwater Dam is a concrete dam located in Duchesne County, Utah, built in 1987. It carries a High hazard potential classification.
Dam profile
NID height · 292 ft292 ft tall and 2,660 ft long, taller than 99% of U.S. dams with a recorded height. Height is drawn to scale against the Statue of Liberty, 305 ft ground to torch; the profile is a generic concrete gravity section and the water level is illustrative.
About Upper Stillwater Dam
The primary purpose of Upper Stillwater Dam is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by Department of the Interior (federal). It impounds the Rock Creek near Duchesne.
The dam stands 292 feet tall and stretches 2,660 feet across, creates a reservoir covering 329 acres, has a maximum storage capacity of 35,253 acre-feet, and collects water from a drainage area of 98 square miles. Completed in 1987, the structure is 39 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. An emergency action plan is in place for this dam. The most recent inspection on record was 08/04/2021.
At 292 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 | Duchesne |
| River/Stream | Rock Creek |
| Coordinates | 40.55990, -110.69990 |
Physical Characteristics
| Dam Type | Concrete |
| NID Height | 292 ft |
| Dam Height | 285 ft |
| Dam Length | 2,660 ft |
| Year Completed | 1987 (39 years old) |
Storage & Hydraulics
| NID Storage | 35,253 acre-ft |
| Max Storage | 35,253 acre-ft |
| Normal Storage | 33,123 acre-ft |
| Surface Area | 329 acres |
| Drainage Area | 98 sq mi |
| Max Discharge | 75,000 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Irrigation |
| Owner | Department of the Interior |
| Owner Type | Federal |
| Hazard Classification | High |
| Condition Assessment | Not assessed |
| Last Inspection | 08/04/2021 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | UT00608 |
| Federal ID | UT00608 |
| More Info | State Dam Safety Program |