O'halloran is an earth dam located in Park County, Montana, built in 1960. It carries a Significant hazard potential classification.
Dam profile
NID height · 23 ft23 ft tall and 200 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 O'halloran
The primary purpose of O'halloran is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by Loyce Ohalloran (private). It impounds the Looking Glass Creek near Clyde Park.
The dam stands 23 feet tall and stretches 200 feet across, and has a maximum storage capacity of 149 acre-feet. Completed in 1960, 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.
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Location
| State | Montana |
| County | Park |
| Nearest City | Clyde Park |
| River/Stream | Looking Glass Creek |
| Coordinates | 45.90820, -110.62875 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 23 ft |
| Dam Height | 23 ft |
| Dam Length | 200 ft |
| Year Completed | 1960 (66 years old) |
Storage & Hydraulics
| NID Storage | 149 acre-ft |
| Max Storage | 149 acre-ft |
| Normal Storage | 71 acre-ft |
Ownership & Safety
| Purpose | Irrigation |
| Owner | Loyce Ohalloran |
| Owner Type | Private |
| Hazard Classification | Significant |
| Condition Assessment | Not assessed |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | MT01555 |
| Federal ID | MT01555 |
| More Info | State Dam Safety Program |