Deadwood Reservoir Report

Last Updated: December 26, 2025

Deadwood is a federal-owned concrete dam located in Garden Valley, Idaho, along the Deadwood River South Fork Payette River.


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Summary

Built in 1931 by the Bureau of Reclamation, this structure primarily serves for hydroelectric power generation, irrigation, and recreation purposes. Standing at 165 feet tall with a 749-foot length, Deadwood has a storage capacity of 191,600 acre-feet and a maximum discharge rate of 11,300 cubic feet per second.

With its high hazard potential and moderate risk assessment rating, Deadwood is regulated, permitted, inspected, and enforced by the Idaho Department of Water Resources. The dam features an uncontrolled spillway with a width of 100 feet and is equipped with valve gates for water release. Despite being in good operational condition, Deadwood underwent modifications in 2004 to strengthen its foundation and seismic resilience, ensuring its continued safety and functionality for water resource and climate enthusiasts to admire and appreciate in the years to come.

Years Modified

2004 - Foundation, 2004 - Seismic

Year Completed

1931

Dam Length

749

Dam Height

143

River Or Stream

DEADWOOD RIVER SOUTH FORK PAYETTE RIVER

Primary Dam Type

Concrete

Surface Area

3800

Hydraulic Height

147

Drainage Area

111

Nid Storage

191600

Structural Height

165

Outlet Gates

Valve - 0

Hazard Potential

High

Foundations

Rock, Soil

Nid Height

165
       
Seasonal Comparison

Weather Forecast

Dam Data Reference

Condition Assessment

Satisfactory
No 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

High
Dams 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.