Arnault Branch Mine Dam
Arnault Branch Mine Dam is an other dam located in Washington County, Missouri, built in 1970. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Arnault Branch Mine Dam
The primary purpose of Arnault Branch Mine Dam is tailings. Tailings dams contain waste material from mining operations — typically a slurry of finely ground rock left over after valuable minerals have been extracted. These structures require ongoing monitoring because tailings can contain heavy metals and other contaminants. The dam is private-owned. It impounds the Trib-arnault Creek near Old Mines.
The dam stands 46 feet tall and stretches 750 feet across, creates a reservoir covering 41 acres, has a maximum storage capacity of 582 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1970, the structure is well into its service life at over 50 years 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 12/01/2022.
At 46 feet, this dam is taller than 91% of dams nationwide.
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 Missouri 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 | Missouri |
| County | Washington |
| Nearest City | Old Mines |
| River/Stream | Trib-arnault Creek |
| Coordinates | 38.01640, -90.81378 |
Physical Characteristics
| Dam Type | Other |
| NID Height | 46 ft |
| Dam Height | 46 ft |
| Dam Length | 750 ft |
| Year Completed | 1970 (56 years old) |
Storage & Hydraulics
| NID Storage | 582 acre-ft |
| Max Storage | 582 acre-ft |
| Normal Storage | 530 acre-ft |
| Surface Area | 41 acres |
| Drainage Area | 0 sq mi |
| Max Discharge | 2,375 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Tailings |
| Owner Type | Private |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 12/01/2022 |
| Emergency Action Plan | No |
Identifiers
| NID ID | MO30716 |
| Federal ID | MO30716 |
| More Info | State Dam Safety Program |