Antioch Reservoir Reservoir Report

Last Updated: December 5, 2025

Antioch Reservoir, also known as Antioch Municipal Reservoir, is nestled in the heart of Antioch, California, and serves as a vital resource for flood risk reduction and water supply.


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Summary

Completed in 1935, this earth dam stands at a height of 30 feet with a hydraulic height of 24.5 feet. The reservoir boasts a storage capacity of 722 acre-feet, offering a surface area of 61 acres and draining an area of 1.68 square miles.

Managed by the local government, Antioch Reservoir is regulated by the Department of Water Resources, Safety of Dams in California. This dam on the Tr San Joaquin River plays a crucial role in ensuring the safety and security of the surrounding community, with a hazard potential deemed to be high but a current condition assessment of satisfactory. The reservoir is a testament to effective water resource management and climate resilience efforts in the region.

As a hub for water enthusiasts and climate advocates, Antioch Reservoir is not only a picturesque landscape but also a symbol of sustainable water management practices. With its rich history dating back to the 1930s, the reservoir continues to play a significant role in flood risk mitigation and water supply for the local community. Its strategic location and design highlight the importance of proactive measures in safeguarding against environmental hazards and ensuring a resilient water infrastructure for generations to come.

Year Completed

1935

Dam Length

450

Dam Height

30

River Or Stream

Tr San Joaquin Riv

Primary Dam Type

Earth

Surface Area

61

Hydraulic Height

24.5

Drainage Area

1.68

Nid Storage

722

Hazard Potential

High

Nid Height

30
       
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.