Hansen Dam Reservoir Report

Last Updated: December 5, 2025

Hansen Dam, also known as Hansen Reservoir, is a Federal-owned Earth dam in Los Angeles, California, constructed by the US Army Corps of Engineers in 1940 for flood risk reduction along the Tujunga Wash.


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Summary

With a height of 97 feet and a storage capacity of 44,990 acre-feet, the dam plays a crucial role in protecting downstream cities like Los Angeles, Burbank, and Glendale from potential flooding. Despite its high hazard potential, USACE has implemented various risk management measures to ensure public safety, including regular inspections, monitoring, and maintenance.

A risk assessment conducted in 2008 identified Hansen Dam as having a moderate risk level due to potential dam instability, structural concerns, and the possibility of embankment erosion during extreme flood events. The dam's failure could have significant consequences on over 300,000 people and cause substantial economic impacts. To mitigate these risks, USACE collaborates closely with state and local emergency managers, conducts emergency exercises, and regularly updates its Emergency Action Plan. Additionally, the agency engages with local communities to enhance flood preparedness and communication strategies.

Looking ahead, USACE plans to reevaluate and update the project risk assessment in 2022 to ensure the most accurate risk response measures are in place. By continuing to monitor and maintain Hansen Dam, implementing proactive risk communication strategies, and working closely with stakeholders, USACE aims to safeguard the surrounding communities and infrastructure from the potential impacts of dam failure and extreme flooding events.

Year Completed

1940

Dam Length

10475

Dam Height

97

River Or Stream

TUJUNGA WASH

Primary Dam Type

Earth

Surface Area

1

Hydraulic Height

92

Drainage Area

152

Nid Storage

44990

Outlet Gates

Vertical Lift - 0

Hazard Potential

High

Nid Height

97
       
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.