Caples Lake Main Reservoir Report

Last Updated: December 4, 2025

Caples Lake Main, also known as Twin Lake, is a privately owned dam located in Kirkwood, California.


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Summary

This earth dam was completed in 1923 and serves primarily for hydroelectric power generation, with additional purposes including recreation. With a height of 86 feet and a hydraulic height of 62 feet, the dam has a storage capacity of 22,338 acre-feet and covers a surface area of 600 acres. Caples Lake Main is situated on Caples Creek and is regulated by the California Department of Water Resources for safety and inspection.

Managed by the Federal Energy Regulatory Commission, Caples Lake Main is a crucial water resource in Alpine County, California. With a high hazard potential, the dam has a risk assessment rating of 2, indicating a significant level of risk. Despite the lack of available condition assessment data, the dam undergoes regular inspections to ensure its safety and compliance with regulatory guidelines. The dam's location in a high-altitude setting makes it susceptible to climatic variability and underscores the importance of effective risk management measures in safeguarding the surrounding area from potential inundation events.

Caples Lake Main plays a vital role in the local water supply and power generation infrastructure, highlighting the intersection of water resource management and climate resilience in the region. As a key component of the hydroelectric system, the dam contributes to the sustainable utilization of water resources while providing recreational opportunities for residents and visitors alike. The ongoing oversight and maintenance of Caples Lake Main underscore the importance of proactive risk management strategies in mitigating potential hazards and ensuring the long-term viability of this essential water resource asset in California's Sierra Nevada region.

Year Completed

1923

Dam Length

1200

Dam Height

86

River Or Stream

Caples Creek

Primary Dam Type

Earth

Surface Area

600

Hydraulic Height

62

Drainage Area

13.5

Nid Storage

22338

Structural Height

65.5

Hazard Potential

High

Nid Height

86
       
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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.