F3b Four Corners Mine Reservoir Report
Last Updated: December 25, 2025
The F3b Four Corners Mine in Florida is a privately owned tailings dam located in Manatee County near the Myakka River.
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Summary
Constructed in 2005, this Earth-type dam stands at a height of 65 feet and has a maximum storage capacity of 45,500 acre-feet. With a surface area of 735 acres and a drainage area of 1.15 square miles, this dam has a significant hazard potential and is classified as a very high risk (1) structure.
Managed by the Florida Department of Environmental Protection, the F3b Four Corners Mine dam has been inspected, regulated, and permitted by state authorities. The dam features a controlled spillway and uncontrolled outlet gates, providing a maximum discharge capacity of 80 cubic feet per second. Despite not having a current condition assessment rating, the dam is regularly monitored for safety and compliance with regulatory standards.
Located in a critical area susceptible to climate change impacts, water resource enthusiasts and climate advocates should pay attention to the F3b Four Corners Mine dam due to its potential environmental risks. With a history of operation solely for tailings management, this dam serves as a reminder of the importance of proper infrastructure maintenance and regulation in safeguarding water resources and ecosystems in the face of changing climate conditions.
Year Completed |
2005 |
Dam Length |
15600 |
Dam Height |
65 |
River Or Stream |
MYAKKA RIVER |
Primary Dam Type |
Earth |
Surface Area |
735 |
Hydraulic Height |
60 |
Drainage Area |
1.15 |
Nid Storage |
45500 |
Structural Height |
68 |
Outlet Gates |
Uncontrolled |
Hazard Potential |
Significant |
Foundations |
Soil |
Nid Height |
68 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Dam Data Reference
Condition Assessment
SatisfactoryNo 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
HighDams 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.
F3b Four Corners Mine