Little Lake is a rockfill dam located in Missoula County, Montana, built in 1912. It carries a Significant hazard potential classification.
Dam profile
NID height · 25 ft25 ft tall and 300 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 rockfill embankment section and the water level is illustrative.
About Little Lake
The primary purpose of Little Lake is water supply. The dam stores water for municipal, industrial, or agricultural use, helping ensure a reliable supply for the surrounding area. The dam is owned by City of Missoula (local government). It impounds the Tr-wrangle Creek near Missoula.
The dam stands 25 feet tall and stretches 300 feet across, creates a reservoir covering 32 acres, has a maximum storage capacity of 298 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1912, the structure is over a century 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. The most recent inspection on record was 08/01/2017.
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Location
| State | Montana |
| County | Missoula |
| Nearest City | Missoula |
| River/Stream | Tr-wrangle Creek |
| Coordinates | 47.04930, -113.92398 |
Physical Characteristics
| Dam Type | Rockfill |
| NID Height | 25 ft |
| Dam Height | 25 ft |
| Dam Length | 300 ft |
| Year Completed | 1912 (114 years old) |
Storage & Hydraulics
| NID Storage | 298 acre-ft |
| Max Storage | 298 acre-ft |
| Normal Storage | 125 acre-ft |
| Surface Area | 32 acres |
| Drainage Area | 0 sq mi |
| Max Discharge | 500 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Water Supply |
| Owner | City of Missoula |
| Owner Type | Local Government |
| Hazard Classification | Significant |
| Condition Assessment | Not assessed |
| Last Inspection | 08/01/2017 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | MT03673 |
| Federal ID | MT03673 |
| More Info | State Dam Safety Program |