20 Dam is a gravity dam located in Custer County, Montana, built in 2003. It carries a Low hazard potential classification and has a poor condition assessment.
Dam profile
NID height · 29 ft29 ft tall and 333 ft long, taller than 65% 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 concrete gravity section and the water level is illustrative.
About 20 Dam
20 Dam is a dam in Custer, Montana. The dam is owned by Doi BLM (federal).
The dam stands 29 feet tall and stretches 333 feet across, creates a reservoir covering 14 acres, and has a maximum storage capacity of 112 acre-feet. Completed in 2003, the structure is relatively new.
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. Its condition is rated poor, meaning the dam has recognized safety deficiencies that require remediation to address risks. The most recent inspection on record was 07/24/2020.
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Location
| State | Montana |
| County | Custer |
| Coordinates | 46.26389, -106.00281 |
Physical Characteristics
| Dam Type | Gravity |
| NID Height | 29 ft |
| Dam Length | 333 ft |
| Year Completed | 2003 (23 years old) |
Storage & Hydraulics
| NID Storage | 112 acre-ft |
| Max Storage | 112 acre-ft |
| Surface Area | 14 acres |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Owner | Doi BLM |
| Owner Type | Federal |
| Hazard Classification | Low |
| Condition Assessment | Poor |
| Last Inspection | 07/24/2020 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | MT03906 |
| Federal ID | MT03906 |
| More Info | State Dam Safety Program |