Bonanza is an earth dam located in Meagher County, Montana, built in 1938. It carries a Significant hazard potential classification.
Dam profile
NID height · 44 ft44 ft tall and 1,020 ft long, taller than 89% 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 Bonanza
The primary purpose of Bonanza is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by David a Voldseth (private). It impounds the Bonanza Creek near Martinsdale.
The dam stands 44 feet tall and stretches 1,020 feet across, creates a reservoir covering 25 acres, has a maximum storage capacity of 409 acre-feet, and collects water from a drainage area of 7 square miles. Completed in 1938, the structure is well-established, with more than 75 years of service.
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.
At 44 feet, this dam is taller than 89% of dams nationwide.
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Location
| State | Montana |
| County | Meagher |
| Nearest City | Martinsdale |
| River/Stream | Bonanza Creek |
| Coordinates | 46.45850, -110.57650 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 44 ft |
| Dam Height | 44 ft |
| Dam Length | 1,020 ft |
| Year Completed | 1938 (88 years old) |
Storage & Hydraulics
| NID Storage | 409 acre-ft |
| Max Storage | 409 acre-ft |
| Normal Storage | 350 acre-ft |
| Surface Area | 25 acres |
| Drainage Area | 7 sq mi |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Irrigation |
| Owner | David a Voldseth |
| Owner Type | Private |
| Hazard Classification | Significant |
| Condition Assessment | Not assessed |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | MT01154 |
| Federal ID | MT01154 |
| More Info | State Dam Safety Program |