Mary Stock is an earth dam located in Campbell County, Wyoming, built in 1964. It carries a Low hazard potential classification and has a fair condition assessment.
Dam profile
NID height · 29 ft29 ft tall and 400 ft long, taller than 65% 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 Mary Stock
The primary purpose of Mary Stock is fire protection, stock, or small fish pond. The dam maintains a small impoundment used for fire suppression, livestock watering, or as a fish pond. The dam is owned by Ryan Land & Livestock (private). It impounds the Mary Draw near Powderville, Montana.
The dam stands 29 feet tall and stretches 400 feet across, creates a reservoir covering 11 acres, and has a maximum storage capacity of 166 acre-feet. Completed in 1964, 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 05/22/2024.
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Location
| State | Wyoming |
| County | Campbell |
| Nearest City | Powderville, Montana |
| River/Stream | Mary Draw |
| Coordinates | 44.82306, -105.28139 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 29 ft |
| Dam Height | 29 ft |
| Dam Length | 400 ft |
| Year Completed | 1964 (62 years old) |
Storage & Hydraulics
| NID Storage | 166 acre-ft |
| Max Storage | 166 acre-ft |
| Normal Storage | 100 acre-ft |
| Surface Area | 11 acres |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Fire Protection, Stock, Or Small Fish Pond |
| Owner | Ryan Land & Livestock |
| Owner Type | Private |
| Hazard Classification | Low |
| Condition Assessment | Fair |
| Last Inspection | 05/22/2024 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | WY01026 |
| Federal ID | WY01026 |
| More Info | State Dam Safety Program |