Mosier No. 1 is an earth dam located in Niobrara County, Wyoming, built in 1974. It carries a Low hazard potential classification and has a fair condition assessment.
Dam profile
NID height · 26 ft26 ft tall and 350 ft long, taller than 55% of U.S. dams with a recorded height. 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 Mosier No. 1
The primary purpose of Mosier No. 1 is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by M & M Cattle LLC (private). It impounds the Little Boggy Creek.
The dam stands 26 feet tall and stretches 350 feet across, creates a reservoir covering 5 acres, has a maximum storage capacity of 60 acre-feet, and collects water from a drainage area of 7 square miles. Completed in 1974, the structure is well into its service life at over 50 years old.
This dam has a low hazard potential classification, meaning that failure would cause minimal damage, limited primarily to the dam owner's property, with no expected loss of life. Its condition is rated fair — the dam has minor deficiencies that are being addressed or do not pose an immediate safety threat. The most recent inspection on record was 08/25/2022.
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Location
| State | Wyoming |
| County | Niobrara |
| River/Stream | Little Boggy Creek |
| Coordinates | 42.97550, -104.66380 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 26 ft |
| Dam Height | 22 ft |
| Dam Length | 350 ft |
| Year Completed | 1974 (52 years old) |
Storage & Hydraulics
| NID Storage | 60 acre-ft |
| Max Storage | 60 acre-ft |
| Normal Storage | 35 acre-ft |
| Surface Area | 5 acres |
| Drainage Area | 7 sq mi |
| Max Discharge | 1,686 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Irrigation |
| Owner | M & M Cattle LLC |
| Owner Type | Private |
| Hazard Classification | Low |
| Condition Assessment | Fair |
| Last Inspection | 08/25/2022 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | WY01769 |
| Federal ID | WY01769 |
| More Info | State Dam Safety Program |