Jenks Lake - Dam Reservoir Report

Last Updated: December 5, 2025

Jenks Lake - Dam is a historic earth dam located in San Bernardino, California, completed in 1875 with a primary purpose of serving as a Fish and Wildlife Pond.


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Summary

Owned by the USDA Forest Service, this dam stands at a height of 30 feet and a length of 150 feet, with a spillway width of 2 feet. The dam is classified as having a high hazard potential, with a moderate risk assessment rating.

Despite its age, Jenks Lake - Dam has not been recently assessed for its condition and does not have a current condition rating. The dam has uncontrolled spillways and outlet gates, indicating potential risks in the event of a flood or emergency. While the risk assessment for the dam is moderate, there is a need for updated emergency action plans and risk management measures to address any potential hazards and ensure the safety of the surrounding area.

Enthusiasts of water resources and climate may find Jenks Lake - Dam an intriguing site due to its historical significance and the need for continued monitoring and maintenance to uphold its safety standards. As a Federal-owned structure, the dam plays a vital role in supporting fish and wildlife habitats in the region. However, with its high hazard potential, there is a call for increased attention to assessing and addressing any risks associated with the dam to ensure the protection of the surrounding community and environment.

Year Completed

1875

Dam Length

150

Dam Height

30

Primary Dam Type

Earth

Structural Height

30

Outlet Gates

Uncontrolled

Hazard Potential

High

Foundations

Rock, Soil

Nid Height

30
       
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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.