Devils Gate Reservoir Report

Last Updated: December 5, 2025

Devils Gate, located in Pasadena, California, is a gravity dam constructed in 1920 for the primary purpose of flood risk reduction along the Arroyo Seco river.


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Summary

With a height of 108 feet and a storage capacity of 2600 acre-feet, this dam plays a crucial role in managing water resources in the region. The structure is regulated by the California Department of Water Resources (DWR) and undergoes regular inspections to ensure its safety and effectiveness.

Despite being classified as having a high hazard potential, Devils Gate is assessed as being in satisfactory condition as of September 2017. The dam's last inspection in October 2020 confirmed its structural integrity and readiness to handle potential emergencies. With Judy Chu (D) as the congressional representative for the area, the local government takes responsibility for the ownership and operation of Devils Gate, highlighting the collaborative efforts to safeguard the community from flood risks and ensure water supply sustainability.

As a significant part of the flood risk reduction infrastructure in Los Angeles County, Devils Gate serves as a vital resource for water management in the region. Its strategic location and design contribute to the protection of surrounding areas from potential inundation, showcasing the importance of proactive measures in mitigating climate-related challenges. With ongoing regulatory oversight and regular maintenance, Devils Gate stands as a testament to effective water resource management and climate resilience efforts in Southern California.

Year Completed

1920

Dam Length

252

Dam Height

108

River Or Stream

Arroyo Seco

Primary Dam Type

Gravity

Surface Area

110

Hydraulic Height

73.5

Drainage Area

29.7

Nid Storage

2600

Hazard Potential

High

Nid Height

108
       
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.