Westermark is an earth dam located in Toole County, Montana, built in 1964. It carries a Low hazard potential classification.
Dam profile
NID height · 45 ft45 ft tall and 360 ft long, taller than 90% 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 Westermark
The primary purpose of Westermark is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by A V Swanberg (private). It impounds the Tr-marias River.
The dam stands 45 feet tall and stretches 360 feet across, has a maximum storage capacity of 131 acre-feet, and collects water from a drainage area of 0 square miles. 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.
At 45 feet, this dam is taller than 90% of dams nationwide.
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Location
| State | Montana |
| County | Toole |
| Nearest City | None |
| River/Stream | Tr-marias River |
| Coordinates | 48.39570, -111.62050 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 45 ft |
| Dam Height | 45 ft |
| Dam Length | 360 ft |
| Year Completed | 1964 (62 years old) |
Storage & Hydraulics
| NID Storage | 131 acre-ft |
| Max Storage | 131 acre-ft |
| Normal Storage | 73 acre-ft |
| Drainage Area | 0 sq mi |
| Max Discharge | 240 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Recreation |
| Owner | A V Swanberg |
| Owner Type | Private |
| Hazard Classification | Low |
| Condition Assessment | Not assessed |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | MT00428 |
| Federal ID | MT00428 |
| More Info | State Dam Safety Program |