Pfaff Irrigation is an earth dam located in Prairie County, Montana, built in 1957. It carries a Significant hazard potential classification.
Dam profile
NID height · 28 ft28 ft tall and 500 ft long, taller than 62% 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 Pfaff Irrigation
The primary purpose of Pfaff Irrigation is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by Pfaff Ranch Inc (private). It impounds the Hay Creek.
The dam stands 28 feet tall and stretches 500 feet across, has a maximum storage capacity of 284 acre-feet, and collects water from a drainage area of 11 square miles. Completed in 1957, 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 | Prairie |
| Nearest City | None |
| River/Stream | Hay Creek |
| Coordinates | 46.88030, -105.98340 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 28 ft |
| Dam Height | 28 ft |
| Dam Length | 500 ft |
| Year Completed | 1957 (69 years old) |
Storage & Hydraulics
| NID Storage | 284 acre-ft |
| Max Storage | 284 acre-ft |
| Normal Storage | 138 acre-ft |
| Drainage Area | 11 sq mi |
| Max Discharge | 600 cfs |
Ownership & Safety
| Purpose | Irrigation |
| Owner | Pfaff Ranch Inc |
| Owner Type | Private |
| Hazard Classification | Significant |
| Condition Assessment | Not assessed |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | MT00346 |
| Federal ID | MT00346 |
| More Info | State Dam Safety Program |