Willow Creek
Willow Creek is an earth dam located in Big Horn County, Montana, built in 1941. It carries a High hazard potential classification and has a fair condition assessment.
About Willow Creek
The primary purpose of Willow Creek is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by Bia (federal). It impounds the Lodge Grass Creek - Tr near Lodge Grass.
The dam stands 136 feet tall and stretches 2,508 feet across, creates a reservoir covering 652 acres, has a maximum storage capacity of 31,710 acre-feet, and collects water from a drainage area of 11 square miles. Completed in 1941, the structure is well-established, with more than 75 years of service.
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 01/06/2021.
At 136 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 Montana 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 | Montana |
| County | Big Horn |
| Nearest City | Lodge Grass |
| River/Stream | Lodge Grass Creek - Tr |
| Coordinates | 45.16333, -107.59639 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 136 ft |
| Dam Height | 113 ft |
| Dam Length | 2,508 ft |
| Year Completed | 1941 (85 years old) |
Storage & Hydraulics
| NID Storage | 31,710 acre-ft |
| Max Storage | 31,710 acre-ft |
| Normal Storage | 23,260 acre-ft |
| Surface Area | 652 acres |
| Drainage Area | 11 sq mi |
| Max Discharge | 22,380 cfs |
| Spillway Type | Controlled |
Ownership & Safety
| Purpose | Irrigation |
| Owner | BIA |
| Owner Type | Federal |
| Hazard Classification | High |
| Condition Assessment | Fair |
| Last Inspection | 01/06/2021 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | MT00963 |
| Federal ID | MT00963 |
| More Info | State Dam Safety Program |