Isabella Dam Reservoir Report

Last Updated: December 5, 2025

Isabella Dam, also known as Isabella Lake, is a critical piece of infrastructure in California's Kern County, serving multiple purposes including flood risk reduction, hydroelectric power generation, irrigation, and recreation.


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Summary

Completed in 1953 by the US Army Corps of Engineers, the earth dam stands at 98 feet high and stretches 1695 feet long, with a storage capacity of 568,000 acre-feet and a maximum storage of 1,202,000 acre-feet. However, a risk assessment conducted in 2005 highlighted concerns about the dam's ability to withstand certain scenarios, leading to its classification as high risk.

To address these concerns, ongoing construction efforts are underway to raise both the main and auxiliary dams, enlarge the spillway, reinforce the structure, and improve the filter and drainage systems. The US Army Corps of Engineers actively manages the risk associated with the project through regular maintenance, emergency action plans, and collaboration with local emergency managers. The dam's emergency plan includes 24/7 staff availability, regular inspections, and monitoring of weather forecasts to make informed decisions on dam operations. Despite the high-risk nature of the project, measures are in place to minimize the potential impact on downstream communities in the event of an emergency.

Year Completed

1953

Dam Length

1695

Dam Height

98

River Or Stream

KERN RIVER

Primary Dam Type

Earth

Surface Area

11200

Hydraulic Height

173

Drainage Area

2074

Nid Storage

568000

Structural Height

185

Hazard Potential

High

Nid Height

185
       
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.