Highway Dept. #2 Reservoir Report
Nearby: Highway Dept. #3 Petranek #1
Last Updated: December 13, 2025
Highway Dept.
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Summary
#2, located in Mellette, South Dakota, is a state-regulated earth dam built in 1970 with a height of 60 feet and a length of 500 feet. It serves the primary purpose of providing water storage for the TRLittle White Offstream river or stream. The dam has a maximum storage capacity of 360 acre-feet and a normal storage level of 80 acre-feet, with a significant hazard potential.
Managed by the South Dakota Department of Natural Resources, Highway Dept. #2 undergoes inspections every 3 years, with the last inspection conducted in September 2017. While the condition assessment is not rated, the dam is structurally sound and meets regulatory standards for permitting, inspection, and enforcement. In the event of an emergency, the dam has not yet prepared an Emergency Action Plan (EAP) or inundation maps, highlighting areas for improvement in risk management and emergency response protocols.
Overall, Highway Dept. #2 plays a crucial role in water resource management in the region, providing vital water storage for the surrounding area. As climate change continues to impact water resources, ensuring the safety and maintenance of dams like Highway Dept. #2 will be essential in mitigating risks and adapting to changing environmental conditions.
Year Completed |
1970 |
Dam Length |
500 |
Dam Height |
60 |
River Or Stream |
TRLITTLE WHITE OFFSTREAM |
Primary Dam Type |
Earth |
Hydraulic Height |
60 |
Nid Storage |
360 |
Hazard Potential |
Significant |
Nid Height |
60 |
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.
Highway Dept. #2