Minidoka Reservoir Report
Nearby: Minidoka South Dike Dewey
Last Updated: December 16, 2025
Minidoka, also known as Lake Walcott, is a federal-owned structure located in Minidoka, Idaho along the Snake River and Columbia River.
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Summary
Constructed in 1906 by the Bureau of Reclamation, this earth dam stands at a height of 88 feet and serves multiple purposes including fish and wildlife pond, hydroelectric power generation, recreation, and water supply. With a storage capacity of 220,200 acre-feet and a surface area of 12,400 acres, Minidoka plays a crucial role in managing water resources in the region.
The dam's controlled spillway, with a width of 2,142 feet, helps regulate water flow and prevent flooding, while its hazard potential is categorized as high due to its age and structural complexity. The structure is inspected regularly by the Bureau of Reclamation to ensure its safety and functionality. Minidoka's risk assessment is classified as very high, emphasizing the importance of effective risk management strategies to mitigate potential hazards and protect surrounding communities. For water resource and climate enthusiasts, Minidoka serves as a fascinating example of how infrastructure can support various environmental and recreational activities while managing water resources effectively.
Year Completed |
1906 |
Dam Length |
670 |
Dam Height |
88 |
River Or Stream |
SNAKE RIVER COLUMBIA RIVER |
Primary Dam Type |
Earth |
Surface Area |
12400 |
Hydraulic Height |
78 |
Drainage Area |
15625 |
Nid Storage |
220200 |
Structural Height |
86 |
Outlet Gates |
Slide (sluice gate) - 0 |
Hazard Potential |
High |
Foundations |
Rock |
Nid Height |
88 |
Seasonal Comparison
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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.
Minidoka