Capitol Lake Dam Reservoir Report
Nearby: Fourth Street Dam Louis Caldwell
Last Updated: December 6, 2025
Capitol Lake Dam, located in Pierre, South Dakota, stands as a vital structure regulating the flow of Hilgers Gulch.
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Summary
This earth dam, completed in 1921, reaches a height of 27 feet and boasts a storage capacity of 127 acre-feet. With a normal storage level of 65 acre-feet, the dam plays a crucial role in managing water resources in the area.
Despite its age, Capitol Lake Dam has been deemed to be in fair condition, with a high hazard potential. Regular inspections are conducted, with the last assessment taking place in March 2020. The dam's spillway is uncontrolled, and its maximum discharge capacity is 2200 cubic feet per second, making it a significant feature in the region's water infrastructure.
The dam's risk assessment is moderate, indicating a need for ongoing monitoring and risk management measures. With its historical significance and importance for water resource management, Capitol Lake Dam serves as a reminder of the critical role that infrastructure plays in mitigating the impacts of climate change and ensuring the sustainability of water resources for future generations.
Year Completed |
1921 |
Dam Length |
600 |
Dam Height |
27 |
River Or Stream |
HILGERS GULCH |
Primary Dam Type |
Earth |
Hydraulic Height |
27 |
Drainage Area |
6 |
Nid Storage |
127 |
Outlet Gates |
None |
Hazard Potential |
High |
Foundations |
Soil |
Nid Height |
27 |
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.
Capitol Lake Dam