Boulder Lake
Boulder Lake is an earth dam located in Sublette County, Wyoming, built in 1964. It carries a Significant hazard potential classification.
About Boulder Lake
The primary purpose of Boulder Lake is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by Boulder Irrigation District (private). It impounds the Boulder Creek near Boulder.
The dam stands 25 feet tall and stretches 380 feet across, creates a reservoir covering 1,676 acres, has a maximum storage capacity of 37,800 acre-feet, and collects water from a drainage area of 126 square miles. Completed in 1964, 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. The most recent inspection on record was 06/24/2025.
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Location
| State | Wyoming |
| County | Sublette |
| Nearest City | Boulder |
| River/Stream | Boulder Creek |
| Coordinates | 42.83620, -109.70540 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 25 ft |
| Dam Height | 25 ft |
| Dam Length | 380 ft |
| Year Completed | 1964 (62 years old) |
Storage & Hydraulics
| NID Storage | 37,800 acre-ft |
| Max Storage | 37,800 acre-ft |
| Normal Storage | 22,280 acre-ft |
| Surface Area | 1,676 acres |
| Drainage Area | 126 sq mi |
| Max Discharge | 6,190 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Irrigation |
| Owner | BOULDER IRRIGATION DISTRICT |
| Owner Type | Private |
| Hazard Classification | Significant |
| Last Inspection | 06/24/2025 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | WY01195 |
| Federal ID | WY01195 |
| More Info | State Dam Safety Program |