Morris Reservoir Report

Last Updated: December 5, 2025

Morris Reservoir, located in Azusa, California, is a gravity dam completed in 1935 primarily for flood risk reduction.


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Summary

With a height of 245 feet and a storage capacity of 27,500 acre-feet, it plays a crucial role in protecting the surrounding areas from potential flooding events. The dam is state-regulated, inspected, and enforced by the Department of Water Resources (DWR) and the Safety of Dams agency, ensuring its structural integrity and safety.

Situated on the San Gabriel River, Morris Reservoir also serves as a water supply source for the region, highlighting its dual purpose in flood control and water management. The reservoir covers an area of 420 acres and has a drainage area of 210 square miles, making it a vital asset for water resource enthusiasts. Despite its high hazard potential, the dam's condition assessment in 2017 deemed it satisfactory, indicating a well-maintained and monitored structure.

Represented by Congresswoman Judy Chu (D), Morris Reservoir stands as a key infrastructure project in the Los Angeles District managed by the local government. With regular inspections and a comprehensive emergency action plan, the dam ensures public safety and environmental protection. Its historical significance, combined with its crucial role in water supply and flood control, makes Morris Reservoir a fascinating site for climate and water resource enthusiasts alike.

Year Completed

1935

Dam Length

750

Dam Height

245

River Or Stream

San Gabriel River

Primary Dam Type

Gravity

Surface Area

420

Hydraulic Height

240

Drainage Area

210

Nid Storage

27500

Hazard Potential

High

Nid Height

245
       
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.