Highway Dept. #3 Reservoir Report
Nearby: Highway Dept. #2 Bak #1
Last Updated: December 8, 2025
Highway Dept.
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Summary
#3 is a state-regulated dam located in Mellette, South Dakota, with a significant hazard potential. Built in 1970, this earth dam stands at a height of 91 feet and has a length of 650 feet, providing a storage capacity of 146 acre-feet. The dam is situated on the TR Little White Offstream, under the jurisdiction of the St. Paul District. It is inspected every 3 years, with the last inspection conducted in September 2017.
The dam's purpose and associated structures are not specified, but it is essential for water resource and climate enthusiasts to note its critical role in flood control and water management in the region. With a maximum discharge capacity of 40 cubic feet per second, Highway Dept. #3 plays a crucial role in protecting downstream communities from potential flooding events. Despite being labeled as "Not Rated" in terms of its condition assessment, continuous monitoring and maintenance efforts are necessary to ensure the dam's integrity and safety.
For those interested in water infrastructure and environmental preservation, Highway Dept. #3 represents a key asset in South Dakota's water management system. As a state-regulated structure, it is subject to regular inspections, permitting, and enforcement by the Department of Agriculture, Natural Resources Division. With its significant hazard potential and storage capacity, this dam serves as a vital component in safeguarding the local community and ecosystem against the impacts of extreme weather events and climate variability.
Year Completed |
1970 |
Dam Length |
650 |
Dam Height |
91 |
River Or Stream |
TR LITTLE WHITE OFFSTREAM |
Primary Dam Type |
Earth |
Hydraulic Height |
91 |
Nid Storage |
146 |
Hazard Potential |
Significant |
Nid Height |
91 |
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. #3