Adelaide
Adelaide is an earth dam located in Big Horn County, Wyoming, built in 1990. It carries a High hazard potential classification.
About Adelaide
The primary purpose of Adelaide is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by Shell Valley Watershed Improvement Dist. (private). It impounds the Adelaide Creek near Shell.
The dam stands 74 feet tall and stretches 805 feet across, creates a reservoir covering 145 acres, has a maximum storage capacity of 5,835 acre-feet, and collects water from a drainage area of 3 square miles. Completed in 1990, the structure is 36 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 10/01/2025.
At 74 feet, this dam is taller than 97% 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 Wyoming 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 | Wyoming |
| County | Big Horn |
| Nearest City | Shell |
| River/Stream | Adelaide Creek |
| Coordinates | 44.52520, -107.40460 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 74 ft |
| Dam Height | 74 ft |
| Dam Length | 805 ft |
| Year Completed | 1990 (36 years old) |
Storage & Hydraulics
| NID Storage | 5,835 acre-ft |
| Max Storage | 5,835 acre-ft |
| Normal Storage | 4,764 acre-ft |
| Surface Area | 145 acres |
| Drainage Area | 3 sq mi |
| Max Discharge | 5,431 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Irrigation |
| Owner | SHELL VALLEY WATERSHED IMPROVEMENT DIST. |
| Owner Type | Private |
| Hazard Classification | High |
| Last Inspection | 10/01/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | WY01099 |
| Federal ID | WY01099 |
| More Info | State Dam Safety Program |