Willow Lake is an earth dam located in Sublette County, Wyoming, built in 1955. It carries a Significant hazard potential classification and has a poor condition assessment.
Dam profile
NID height · 20 ft20 ft tall and 320 ft long. Height is drawn to scale against a two-story house, about 25 ft; the profile is a generic embankment section and the water level is illustrative.
About Willow Lake
The primary purpose of Willow Lake is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by Wilson, Binning, Bayer, Jorgensen, Etal (private). It impounds the Lake Creek near Boulder.
The dam stands 20 feet tall and stretches 320 feet across, creates a reservoir covering 1,958 acres, has a maximum storage capacity of 32,125 acre-feet, and collects water from a drainage area of 32 square miles. Completed in 1955, the structure is well into its service life at over 50 years old.
This dam has a significant hazard potential classification, meaning that a failure could cause significant economic damage — flooding roads, bridges, or property downstream — but is not expected to result in loss of life. Its condition is rated poor, meaning the dam has recognized safety deficiencies that require remediation to address risks. The most recent inspection on record was 06/03/2024.
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Location
| State | Wyoming |
| County | Sublette |
| Nearest City | Boulder |
| River/Stream | Lake Creek |
| Coordinates | 42.99300, -109.90900 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 20 ft |
| Dam Height | 20 ft |
| Dam Length | 320 ft |
| Year Completed | 1955 (71 years old) |
Storage & Hydraulics
| NID Storage | 32,125 acre-ft |
| Max Storage | 32,125 acre-ft |
| Normal Storage | 22,630 acre-ft |
| Surface Area | 1,958 acres |
| Drainage Area | 32 sq mi |
| Max Discharge | 625 cfs |
| Spillway Type | Controlled |
Ownership & Safety
| Purpose | Irrigation |
| Owner | Wilson, Binning, Bayer, Jorgensen, Etal |
| Owner Type | Private |
| Hazard Classification | Significant |
| Condition Assessment | Poor |
| Last Inspection | 06/03/2024 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | WY01192 |
| Federal ID | WY01192 |
| More Info | State Dam Safety Program |