Alpine Auxiliary No. 2 Reservoir Report

Last Updated: December 5, 2025

Alpine Auxiliary No.


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Summary

2 is a private-owned dam located in Dorrington, California, serving multiple purposes including hydroelectric power generation, recreation, and water supply. This rockfill dam stands at 21 meters in height and has a storage capacity of 4,300 acre-feet, with a maximum discharge of 3,400 cubic feet per second. Situated on Silver Creek, this dam is regulated by the California Department of Water Resources and inspected by the Federal Energy Regulatory Commission, ensuring its safety and compliance with state and federal regulations.

With a low hazard potential and a moderate risk assessment rating, Alpine Auxiliary No. 2 provides essential services while also offering recreational opportunities in the surrounding area. The dam has a spillway width of 166 meters and an uncontrolled spillway type, contributing to its efficient water management capabilities. The dam's condition assessment is not available, highlighting the need for ongoing monitoring and maintenance to ensure its continued operation and safety for the community.

Alpine Auxiliary No. 2 plays a crucial role in the water resource infrastructure of Alpine County, California, with its strategic location and reliable operation contributing to the region's water management and energy needs. With a comprehensive emergency action plan in place and regular inspections by regulatory agencies, this dam stands as a testament to effective dam management practices and the importance of ensuring the safety and resilience of critical water infrastructure in the face of changing climate conditions.

Dam Length

166

Dam Height

21

River Or Stream

Silver Creek

Primary Dam Type

Rockfill

Surface Area

172

Hydraulic Height

21

Drainage Area

5

Nid Storage

4300

Structural Height

21

Hazard Potential

Low

Nid Height

21
       
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.