Bottom Diggins Dam
Bottom Diggins Dam is an earth dam located in Washington County, Missouri, built in 1957. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Bottom Diggins Dam
The primary purpose of Bottom Diggins 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 Tr-mill Creek near Tiff.
The dam stands 41 feet tall and stretches 1,300 feet across, creates a reservoir covering 38 acres, has a maximum storage capacity of 300 acre-feet, and collects water from a drainage area of 1 square miles. Completed in 1957, 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. An emergency action plan is in place for this dam. The most recent inspection on record was 12/13/2022.
At 41 feet, this dam is taller than 88% 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 | Tiff |
| River/Stream | Tr-mill Creek |
| Coordinates | 38.00524, -90.70728 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 41 ft |
| Dam Height | 41 ft |
| Dam Length | 1,300 ft |
| Year Completed | 1957 (69 years old) |
Storage & Hydraulics
| NID Storage | 300 acre-ft |
| Max Storage | 300 acre-ft |
| Normal Storage | 51 acre-ft |
| Surface Area | 38 acres |
| Drainage Area | 1 sq mi |
| Max Discharge | 8,335 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Tailings |
| Owner Type | Private |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 12/13/2022 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | MO30750 |
| Federal ID | MO30750 |
| More Info | State Dam Safety Program |