Angwin Reservoir Report

Last Updated: December 5, 2025

Angwin, located in Napa, California, is home to a significant earth dam known as the Moore Creek Dam.


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Summary

Completed in 1967, this dam serves the primary purpose of water supply for irrigation and other uses. With a dam height of 35 feet and a capacity of 156 acre-feet, Angwin's dam plays a crucial role in managing water resources in the region.

State-regulated and inspected, the Moore Creek Dam in Angwin boasts a satisfactory condition assessment, highlighting its importance in ensuring water safety and security for the surrounding community. Despite its significant hazard potential, the dam's structural integrity and maintenance have been deemed satisfactory, providing peace of mind for water resource and climate enthusiasts in the area.

With its location in the Sacramento District and under the jurisdiction of the California Department of Water Resources, the Moore Creek Dam in Angwin stands as a vital infrastructure for water management. Its association with the nearby Moore Creek and its capacity to handle drainage from a 0.05 square mile area further underscore its importance in safeguarding water resources and supporting sustainable development in the region.

Year Completed

1967

Dam Length

621

Dam Height

35

River Or Stream

Moore Creek

Primary Dam Type

Earth

Surface Area

14

Hydraulic Height

31

Drainage Area

0.05

Nid Storage

156

Hazard Potential

Significant

Nid Height

35
       
Seasonal Comparison

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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.