Anderson Ranch Reservoir Report

Last Updated: December 20, 2025

Anderson Ranch is a federal-owned dam located in Reclamation Village, Idaho, along the South Fork Boise River.


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Summary

Built in 1946 by the Bureau of Reclamation, this earth dam stands at 456 feet high and serves multiple purposes including flood risk reduction, hydroelectric power generation, and irrigation. With a storage capacity of 503,500 acre-feet and a normal storage of 464,216 acre-feet, Anderson Ranch plays a crucial role in water management and resource allocation in the region.

The dam's spillway, with a controlled design and a width of 50 feet, helps manage water flow and prevent flooding during periods of high discharge. The hazard potential of Anderson Ranch is classified as high, and a risk assessment has deemed it to have a very high risk level. Despite its age, the dam's condition assessment is currently not available, highlighting the need for ongoing monitoring and maintenance to ensure its continued safety and effectiveness in water resource management.

As a key component of the Bureau of Reclamation's operations, Anderson Ranch demonstrates the intricate balance between water resource management, infrastructure development, and environmental conservation. Its location in a scenic area surrounded by the natural beauty of Idaho makes it not only a critical piece of infrastructure but also a symbol of the complex relationship between human needs and environmental stewardship in the face of changing climate dynamics.

Year Completed

1946

Dam Length

1350

Dam Height

456

River Or Stream

SOUTH FORK BOISE RIVER

Primary Dam Type

Earth

Surface Area

4815

Hydraulic Height

330

Drainage Area

960

Nid Storage

503500

Structural Height

456

Hazard Potential

High

Foundations

Rock

Nid Height

456
       
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.