Sweetwater Main

About Sweetwater Main

The primary purpose of Sweetwater Main is water supply. The dam stores water for municipal, industrial, or agricultural use, helping ensure a reliable supply for the surrounding area. The dam is owned by Sweetwater Authority (public utility). It impounds the Sweetwater River near San Diego/chula Vista.

The dam stands 112 feet tall and stretches 700 feet across, creates a reservoir covering 936 acres, has a maximum storage capacity of 27,689 acre-feet, and collects water from a drainage area of 182 square miles. Completed in 1888, the structure is over a century old.

This dam carries a high hazard potential classification, which means that a failure or uncontrolled release of water would likely cause loss of human life. This classification reflects the consequences of failure, not the likelihood — it indicates that people live or work in the area downstream. Its condition is rated fair — the dam has minor deficiencies that are being addressed or do not pose an immediate safety threat. An emergency action plan is in place for this dam. The most recent inspection on record was 02/05/2025.

At 112 feet, this dam is taller than 98% of all dams in the United States.

Living Downstream

If you live or work downstream of this dam, consider taking these steps: learn your local evacuation routes, check whether your county emergency management office has a dam failure inundation map, and sign up for local emergency alerts. The California dam safety program can provide more specific information about emergency planning for this structure.

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