South Fork Blackwater River Dam A-20 Reservoir Report
Last Updated: December 7, 2025
South Fork Blackwater River Dam A-20, located in Kingsville, Missouri, serves as a crucial infrastructure for grade stabilization along the West Branch of the South Fork Blackwater River.
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Summary
Built in 1964 by the USDA NRCS, this earth dam stands at a height of 31 feet and spans 665 feet in length, providing a storage capacity of 240 acre-feet for flood control purposes. With a low hazard potential and a moderate risk assessment score of 3, this dam is considered to be in satisfactory condition, although it has not been rated in terms of its structural integrity.
Despite being classified as a non-regulated structure by the state, South Fork Blackwater River Dam A-20 plays a vital role in managing water resources in Johnson County, Missouri. With a normal storage capacity of 76 acre-feet and a maximum discharge rate of 967 cubic feet per second, this dam helps to mitigate the impact of flooding events in the area. Its uncontrolled spillway, with a width of 85 feet, allows for excess water to safely flow downstream, reducing the risk of overtopping and potential damage to downstream properties.
As water resource and climate enthusiasts, it is important to recognize the significance of structures like South Fork Blackwater River Dam A-20 in safeguarding communities and ecosystems from the impacts of extreme weather events. By understanding the design and purpose of such infrastructure, we can appreciate the valuable role they play in promoting water security and resilience in the face of a changing climate.
Year Completed |
1964 |
Dam Length |
665 |
Dam Height |
29 |
River Or Stream |
W.BRANCH S.FK.BLACKWATER |
Primary Dam Type |
Earth |
Surface Area |
1 |
Hydraulic Height |
29 |
Drainage Area |
96 |
Nid Storage |
240 |
Structural Height |
31 |
Outlet Gates |
None |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
31 |
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.
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