Mallard Dam Reservoir Report
Nearby: Nels (Nid) Petersen Dam
Last Updated: December 13, 2025
Mallard Dam, located in Lyman, South Dakota, on Cedar Creek, is a federal-owned Earth dam completed in 1942.
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Summary
With a height of 20 feet and a length of 400 feet, this dam serves the primary purpose of water storage, with a maximum storage capacity of 166 acre-feet. Despite not being regulated by the state, Mallard Dam has a low hazard potential and is currently rated as "Not Rated" in terms of condition assessment.
The dam, managed by the St. Paul District of the US Army Corps of Engineers, plays a crucial role in managing the flow of Cedar Creek and ensuring water availability in the region. With a maximum discharge capacity of 2080 cubic feet per second, Mallard Dam provides important water resource benefits to the surrounding community. Although not currently inspected or rated, the dam's low hazard potential indicates a stable and secure structure that contributes to water resource management and climate resilience efforts in the area.
As an integral part of South Dakota's water infrastructure, Mallard Dam represents a key component in the state's water management strategy. Its strategic location and design make it a vital asset for ensuring water availability, especially during periods of drought or increased water demand. With its historical significance and continued role in water storage and management, Mallard Dam stands as a testament to the importance of sustainable water resource practices in the face of changing climate conditions.
Year Completed |
1942 |
Dam Length |
400 |
Dam Height |
20 |
River Or Stream |
CEDAR CREEK |
Primary Dam Type |
Earth |
Hydraulic Height |
20 |
Nid Storage |
166 |
Hazard Potential |
Low |
Nid Height |
20 |
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 Dam