Blackwell Mine Dam Reservoir Report

Last Updated: December 6, 2025

Blackwell Mine Dam, located in Potosi, Missouri, serves as a crucial structure for tailings storage.


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Summary

Completed in 1980, this rockfill dam stands at 85 feet tall and spans a length of 2500 feet, with a storage capacity of 2100 acre-feet. The dam is regulated by the Dam and Reservoir Safety Program in Missouri, ensuring that it undergoes regular inspections and maintenance to uphold its high hazard potential.

The dam's primary purpose is to contain tailings from mining activities, with a surface area of 58 acres and a drainage area of the same size. Although the dam has a moderate risk assessment rating, its condition assessment as of December 2007 is satisfactory. Despite its uncontrolled spillway type, the dam has a spillway width of 58 feet to handle a maximum discharge of 1006 cubic feet per second. With a history of regular inspections and a designated emergency action plan, Blackwell Mine Dam remains a vital component of water resource management in the region.

Water resource and climate enthusiasts can appreciate the role of Blackwell Mine Dam in maintaining the integrity of the surrounding environment and ensuring the safety of downstream communities. As a privately owned structure in Washington County, Missouri, the dam's design and construction reflect the importance of tailings storage in mining operations. With state-regulated permitting, inspection, and enforcement protocols in place, the dam stands as a testament to responsible water resource management and climate resilience in the face of high hazard potential.

Year Completed

1980

Dam Length

2500

Dam Height

85

River Or Stream

TRIB MADDEN CREEK

Primary Dam Type

Rockfill

Surface Area

58

Drainage Area

58

Nid Storage

2100

Structural Height

85

Outlet Gates

None

Hazard Potential

High

Foundations

Unlisted/Unknown

Nid Height

85
       
Seasonal Comparison

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Dam Data Reference

Condition Assessment

Satisfactory
No existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
Fair
No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action. Note: Rare or extreme event is defined by the regulatory agency based on their minimum
Poor A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency. Investigations and studies are necessary.
Unsatisfactory
A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.
Not Rated
The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Not Available
Dams for which the condition assessment is restricted to approved government users.

Hazard Potential Classification

High
Dams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
Significant
Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environment damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
Low
Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner's property.
Undetermined
Dams for which a downstream hazard potential has not been designated or is not provided.
Not Available
Dams for which the downstream hazard potential is restricted to approved government users.