Duvall Reservoir Report

Last Updated: December 5, 2025

Duvall, also known as Duvall Lake, is a privately owned dam located in Napa, California, along the Tr Pope Creek.


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Summary

Constructed in 1940, this earth dam stands 30 feet tall and spans 1500 feet in length, with a storage capacity of 242 acre-feet. Its primary purpose is flood risk reduction, with additional functions including irrigation and water supply. The dam is regulated by the California Department of Water Resources (DWR) and is subject to state permitting, inspection, and enforcement requirements.

Despite its satisfactory condition assessment as of September 2017, Duvall poses a high hazard potential due to its location and design. Regular inspections are conducted, with the last one taking place in October 2020. While an emergency action plan (EAP) is not currently prepared, the dam meets state guidelines for safety and risk management. The dam's hazard potential underscores the importance of ongoing monitoring and maintenance to ensure the safety of downstream communities and surrounding areas in the event of a flood or other emergency.

With its critical role in flood risk reduction and water management in the region, Duvall serves as a key infrastructure asset for the San Francisco District. Managed by the Natural Resources Conservation Service, the dam contributes to the protection of local communities and agricultural lands from potential flooding events. As water resource and climate enthusiasts, understanding the complexities and responsibilities associated with dams like Duvall highlights the interconnected nature of water management and environmental stewardship in safeguarding our communities and natural resources.

Year Completed

1940

Dam Length

1500

Dam Height

30

River Or Stream

Tr Pope Creek

Primary Dam Type

Earth

Surface Area

17

Hydraulic Height

24

Drainage Area

1.3

Nid Storage

242

Hazard Potential

High

Nid Height

30
       
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.