Anchor South Dam
Anchor South Dam is an earth dam located in Beaverhead County, Montana, built in 1904. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Anchor South Dam
The primary purpose of Anchor South Dam is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by Beaverhead Water Co (private). It impounds the Tr-birch Creek near Twin Bridges.
The dam stands 11 feet tall and stretches 113 feet across, creates a reservoir covering 34 acres, has a maximum storage capacity of 510 acre-feet, and collects water from a drainage area of 3 square miles. Completed in 1904, the structure is over a century old.
This dam carries a high hazard potential classification, which means that a failure or uncontrolled release of water would likely cause loss of human life. This classification reflects the consequences of failure, not the likelihood — it indicates that people live or work in the area downstream. Its condition is rated satisfactory, indicating no existing or potential dam safety deficiencies are recognized. Notably, no emergency action plan is currently on file for this high-hazard dam. The most recent inspection on record was 09/18/2024.
Living Downstream
If you live or work downstream of this dam, consider taking these steps: learn your local evacuation routes, check whether your county emergency management office has a dam failure inundation map, and sign up for local emergency alerts. The Montana dam safety program can provide more specific information about emergency planning for this structure.
Search for dams near your address to see all dams in your area with hazard classifications and safety data.
Location
| State | Montana |
| County | Beaverhead |
| Nearest City | Twin Bridges |
| River/Stream | Tr-birch Creek |
| Coordinates | 45.43225, -113.00063 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 11 ft |
| Dam Height | 11 ft |
| Dam Length | 113 ft |
| Year Completed | 1904 (122 years old) |
Storage & Hydraulics
| NID Storage | 510 acre-ft |
| Max Storage | 510 acre-ft |
| Normal Storage | 206 acre-ft |
| Surface Area | 34 acres |
| Drainage Area | 3 sq mi |
| Max Discharge | 194 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Irrigation |
| Owner | BEAVERHEAD WATER CO |
| Owner Type | Private |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 09/18/2024 |
| Emergency Action Plan | No |
Identifiers
| NID ID | MT00821 |
| Federal ID | MT00821 |
| More Info | State Dam Safety Program |