Portwine #1 is an earth dam located in Powder River County, Montana, built in 1934. It carries a Low hazard potential classification.
Dam profile
NID height · 25 ft25 ft tall and 200 ft long, taller than 50% 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 Portwine #1
The primary purpose of Portwine #1 is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by Zilbert Portwine (private). It impounds the Tr-bay Horse Creek near Broadus.
The dam stands 25 feet tall and stretches 200 feet across, and has a maximum storage capacity of 76 acre-feet. Completed in 1934, the structure is well-established, with more than 75 years of service.
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.
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Location
| State | Montana |
| County | Powder River |
| Nearest City | Broadus |
| River/Stream | Tr-bay Horse Creek |
| Coordinates | 45.08450, -105.64600 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 25 ft |
| Dam Height | 25 ft |
| Dam Length | 200 ft |
| Year Completed | 1934 (92 years old) |
Storage & Hydraulics
| NID Storage | 76 acre-ft |
| Max Storage | 76 acre-ft |
| Normal Storage | 65 acre-ft |
Ownership & Safety
| Purpose | Irrigation |
| Owner | Zilbert Portwine |
| Owner Type | Private |
| Hazard Classification | Low |
| Condition Assessment | Not assessed |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | MT01733 |
| Federal ID | MT01733 |
| More Info | State Dam Safety Program |