Middlefield Reservoir Reservoir Report

Last Updated: December 5, 2025

Middlefield Reservoir, located in Fremont, California, is a vital offstream water supply resource managed by the local government.


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Summary

Completed in 1958, this Earth-type dam stands at a height of 147 feet and spans 1017 feet, providing a maximum storage capacity of 22 acre-feet. With a surface area of 2 acres, Middlefield Reservoir serves as a crucial water source for the region, especially in times of high demand.

This reservoir is regulated by the Department of Water Resources (DWR) and is subject to regular inspections to ensure its safety and functionality. Despite its high hazard potential, Middlefield Reservoir has been assessed as satisfactory in condition as of September 2017. Emergency action plans are in place, although details on their last revision and meeting guidelines are not available. As a key water supply infrastructure in Alameda County, Middlefield Reservoir plays a significant role in water management and climate resilience efforts in the region.

For water resource and climate enthusiasts, Middlefield Reservoir offers a fascinating glimpse into the intersection of infrastructure, water supply, and environmental sustainability. Positioned within the Sacramento District, this reservoir not only meets the water needs of the local community but also highlights the importance of effective dam management and regulatory oversight. As climate change impacts water resources, understanding and monitoring structures like Middlefield Reservoir become increasingly crucial for ensuring water security and resilience in the face of evolving environmental challenges.

Year Completed

1958

Dam Length

1017

Dam Height

147

River Or Stream

Offstream

Primary Dam Type

Earth

Surface Area

2

Hydraulic Height

147

Nid Storage

22

Hazard Potential

High

Nid Height

147
       
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.