Gravelly Range Lake is an earth dam located in Lewis and Clark County, Montana, built in 1964. It carries a Significant hazard potential classification.
Dam profile
NID height · 12 ft12 ft tall and 36 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 Gravelly Range Lake
The primary purpose of Gravelly Range Lake is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by Ed Grady (private). It impounds the Tr-cottonwood Creek near Canyon Creek.
The dam stands 12 feet tall and stretches 36 feet across, has a maximum storage capacity of 627 acre-feet, and collects water from a drainage area of 3 square miles. Completed in 1964, 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 | Lewis and Clark |
| Nearest City | Canyon Creek |
| River/Stream | Tr-cottonwood Creek |
| Coordinates | 46.83560, -112.37020 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 12 ft |
| Dam Height | 12 ft |
| Dam Length | 36 ft |
| Year Completed | 1964 (62 years old) |
Storage & Hydraulics
| NID Storage | 627 acre-ft |
| Max Storage | 627 acre-ft |
| Normal Storage | 483 acre-ft |
| Drainage Area | 3 sq mi |
| Max Discharge | 20 cfs |
Ownership & Safety
| Purpose | Irrigation |
| Owner | Ed Grady |
| Owner Type | Private |
| Hazard Classification | Significant |
| Condition Assessment | Not assessed |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | MT00300 |
| Federal ID | MT00300 |
| More Info | State Dam Safety Program |