Mallard Reservoir Report
Nearby: Seiler Dam James Seiler
Last Updated: December 13, 2025
Mallard is a state-regulated earth dam located in South Dakota, specifically in Corson County near the city of Bullhead.
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Summary
Built in 1935 by the Works Progress Administration (WPA), this dam stands at a height of 25 feet and has a length of 670 feet, with a maximum storage capacity of 859 acre-feet. It is designed with a spillway type of "Uncontrolled" and has a maximum discharge of 3500 cubic feet per second.
With a low hazard potential and a moderate risk assessment rating of 3, Mallard dam is inspected every three years to ensure its structural integrity and safety. The dam is not currently rated for its condition assessment, and emergency action plans are not prepared or updated as of the latest available data in 2018. Despite its low hazard potential, Mallard remains a crucial water resource structure for managing the TR-HUMP river or stream and providing essential water storage for the surrounding area. For water resource and climate enthusiasts, Mallard offers a fascinating glimpse into the historical construction and ongoing management of water infrastructure in South Dakota.
Year Completed |
1935 |
Dam Length |
670 |
Dam Height |
25 |
River Or Stream |
TR-HUMP |
Primary Dam Type |
Earth |
Hydraulic Height |
25 |
Drainage Area |
17 |
Nid Storage |
859 |
Outlet Gates |
None |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
25 |
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.
Mallard