Mary No. 2 is an earth dam located in Johnson County, Wyoming, built in 1973. It carries a Low hazard potential classification and has a fair condition assessment.
Dam profile
NID height · 22 ft22 ft tall and 430 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 Mary No. 2
The primary purpose of Mary No. 2 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 Aht Land LLC (private). It impounds the Arpan Draw near Arvada.
The dam stands 22 feet tall and stretches 430 feet across, creates a reservoir covering 7 acres, and has a maximum storage capacity of 95 acre-feet. Completed in 1973, 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 07/08/2020.
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Location
| State | Wyoming |
| County | Johnson |
| Nearest City | Arvada |
| River/Stream | Arpan Draw |
| Coordinates | 44.48250, -106.29490 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 22 ft |
| Dam Height | 22 ft |
| Dam Length | 430 ft |
| Year Completed | 1973 (53 years old) |
Storage & Hydraulics
| NID Storage | 95 acre-ft |
| Max Storage | 95 acre-ft |
| Normal Storage | 51 acre-ft |
| Surface Area | 7 acres |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Fire Protection, Stock, Or Small Fish Pond |
| Owner | Aht Land LLC |
| Owner Type | Private |
| Hazard Classification | Low |
| Condition Assessment | Fair |
| Last Inspection | 07/08/2020 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | WY00601 |
| Federal ID | WY00601 |
| More Info | State Dam Safety Program |