Wm T Malloy Reservoir Report
Nearby: Simons Bros. Pasture 8
Last Updated: December 6, 2025
Wm T Malloy is a privately owned dam located in Perkins, South Dakota, along the TR-GRAND RIVER.
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Summary
Constructed in 1953 by the Natural Resources Conservation Service, this Earth-type dam stands at 22 feet high and spans 630 feet in length. With a storage capacity of 143 acre-feet and a maximum discharge of 6000 cubic feet per second, Wm T Malloy serves as a vital water resource for the surrounding area.
Despite its age, Wm T Malloy has a low hazard potential and is currently rated as "Not Rated" in terms of condition assessment. While the dam has not been inspected recently and lacks detailed emergency action and risk management plans, it remains under state jurisdiction and is subject to permitting, inspection, and enforcement by the South Dakota Department of Environment and Natural Resources. With the potential for future modifications and improvements, Wm T Malloy continues to play a crucial role in water resource management and climate resilience efforts in the region.
Water resource and climate enthusiasts can appreciate Wm T Malloy as a key infrastructure supporting water storage and management in South Dakota. As a privately owned dam with a long history of service, this Earth-type structure represents a valuable asset in the state's efforts to ensure water security and mitigate the impacts of climate change. While there are opportunities for further assessment and planning to enhance the dam's safety and efficiency, Wm T Malloy stands as a testament to the importance of proactive water resource management in a changing climate landscape.
Year Completed |
1953 |
Dam Length |
630 |
Dam Height |
22 |
River Or Stream |
TR-GRAND RIVER |
Primary Dam Type |
Earth |
Hydraulic Height |
22 |
Nid Storage |
143 |
Hazard Potential |
Low |
Nid Height |
22 |
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.
Wm T Malloy