Dyer

Dyer is an earth dam located in Alameda County, California, built in 2011. It carries a High hazard potential classification and has a fair condition assessment.

About Dyer

The primary purpose of Dyer 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 California Department Of Water Resources (state).

The dam stands 30 feet tall and stretches 1,850 feet across, creates a reservoir covering 25 acres, has a maximum storage capacity of 525 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 2011, the structure is relatively new.

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 11/18/2025.

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.

Search for dams near your address to see all dams in your area with hazard classifications and safety data.

High HazardFair ConditionEmergency Action Plan: Yes

Location

StateCalifornia
CountyAlameda
Nearest CityLivermore
Coordinates37.75980, -121.67400

Physical Characteristics

Dam TypeEarth
NID Height30 ft
Dam Height30 ft
Dam Length1,850 ft
Year Completed2011 (15 years old)

Storage & Hydraulics

NID Storage525 acre-ft
Max Storage525 acre-ft
Surface Area25 acres
Drainage Area0 sq mi

Ownership & Safety

PurposeWater Supply
OwnerCalifornia Department of Water Resources
Owner TypeState
Hazard ClassificationHigh
Condition AssessmentFair
Last Inspection11/18/2025
Emergency Action PlanYes

Identifiers

NID IDCA01491
Federal IDCA01491
More InfoState Dam Safety Program

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