Sweetwater Main Reservoir Report

Last Updated: December 5, 2025

Sweetwater Main, located in Chula Vista, California, is a gravity dam on the Sweetwater River with a height of 112 feet and a hydraulic height of 99 feet.


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Summary

Completed in 1888, this dam serves primarily for water supply purposes, with a storage capacity of 27,689 acre-feet and a surface area of 936 acres. The dam is regulated by the Department of Water Resources and is subject to regular inspections to ensure its structural integrity.

Despite being rated as having a high hazard potential, Sweetwater Main is currently assessed to be in fair condition as of September 2017. The dam has not undergone any modifications in recent years, and its emergency action plan was last revised in February 2021. The surrounding area is at risk of inundation in the event of a breach, but specific risk management measures and assessments are not detailed in the available data.

Water resource and climate enthusiasts interested in the historical significance and technical details of Sweetwater Main will find this structure to be a key component of water management in San Diego County. With its role in irrigation, tailings, and water supply, this dam stands as a testament to California's long-standing efforts to harness and protect its water resources.

Year Completed

1888

Dam Length

700

Dam Height

112

River Or Stream

Sweetwater River

Primary Dam Type

Gravity

Surface Area

936

Hydraulic Height

99

Drainage Area

182

Nid Storage

27689

Hazard Potential

High

Nid Height

112
       
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.