J Janssen #1 is an earth dam located in Powder River County, Montana, built in 1940. It carries a Low hazard potential classification.
Dam profile
NID height · 16 ft16 ft tall and 480 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 J Janssen #1
The primary purpose of J Janssen #1 is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by John Janssen (private). It impounds the Hay Creek near Mizpah.
The dam stands 16 feet tall and stretches 480 feet across, has a maximum storage capacity of 151 acre-feet, and collects water from a drainage area of 15 square miles. Completed in 1940, 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.
Search for dams near your address to see all dams in your area with hazard classifications and safety data.
Location
| State | Montana |
| County | Powder River |
| Nearest City | Mizpah |
| River/Stream | Hay Creek |
| Coordinates | 45.72060, -105.46830 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 16 ft |
| Dam Height | 16 ft |
| Dam Length | 480 ft |
| Year Completed | 1940 (86 years old) |
Storage & Hydraulics
| NID Storage | 151 acre-ft |
| Max Storage | 151 acre-ft |
| Normal Storage | 151 acre-ft |
| Drainage Area | 15 sq mi |
| Max Discharge | 500 cfs |
Ownership & Safety
| Purpose | Irrigation |
| Owner | John Janssen |
| Owner Type | Private |
| Hazard Classification | Low |
| Condition Assessment | Not assessed |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | MT01723 |
| Federal ID | MT01723 |
| More Info | State Dam Safety Program |