Diamond Valley Lake Reservoir Report

Last Updated: December 5, 2025

Diamond Valley Lake, located in Winchester, California, is a stunning reservoir primarily used for water supply but also offering recreational opportunities.


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Summary

Completed in 2000, this earth dam stands at an impressive height of 284 feet and has a storage capacity of 800,000 acre-feet. With a surface area of 4860 acres, the lake provides a vital resource for the surrounding area while also serving as a recreational destination for visitors.

Managed by a public utility, Diamond Valley Lake is regulated by the California Department of Water Resources (DWR) for safety and inspection. The dam has a high hazard potential but is currently rated as satisfactory in condition, with the last assessment conducted in September 2017. The reservoir is situated on the Domenigoni Valley Creek and is under the jurisdiction of the state of California, ensuring that it meets all necessary permitting, inspection, and enforcement requirements to maintain its operations.

Visitors to Diamond Valley Lake can enjoy various water-based activities and nature experiences within its picturesque setting. With its strategic location in Riverside County and close proximity to the city of Winchester, the reservoir serves as a vital water source for the region while offering a tranquil escape for water resource and climate enthusiasts alike.

Year Completed

2000

Dam Length

8300

Dam Height

284

River Or Stream

Domenigoni Valley Cr

Primary Dam Type

Earth

Surface Area

4860

Hydraulic Height

271

Nid Storage

800000

Hazard Potential

High

Nid Height

284
       
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.