Crystal Reservoir Report

Last Updated: December 5, 2025

Crystal is a privately owned dam located in St Helena, California, along the Tr Crystal Crk river/stream.


°F

°F

mph

Wind

%

Humidity

Summary

Completed in 1952, this earth dam stands at a height of 51 feet and has a storage capacity of 105 acre-feet. The primary purpose of Crystal Dam is for water supply, with additional uses including irrigation and recreation. It is regulated by the California Department of Water Resources (DWR) and undergoes regular inspections to ensure its safety and compliance with state regulations.

With a high hazard potential, Crystal Dam is deemed to be in satisfactory condition as of the last assessment in September 2017. The dam is subject to annual inspections and has an emergency action plan in place, although details on its compliance with guidelines and the preparation of inundation maps are not specified. Despite these potential risks, Crystal Dam serves as a crucial water resource for the surrounding area, providing essential water supply for agricultural and recreational activities. Enthusiasts of water resources and climate will find interest in the history and operational aspects of this significant structure in Napa, California.

Overall, Crystal Dam is a vital component of the water infrastructure in Napa County, contributing to the region's water supply and supporting various purposes such as irrigation and recreation. Managed by a private entity, the dam is subject to state regulations and inspections to ensure its safety and functionality. As part of the Sacramento District, Crystal Dam plays a key role in the management and distribution of water resources in the area, highlighting the importance of sustainable water management practices in the face of climate challenges.

Year Completed

1952

Dam Length

475

Dam Height

51

River Or Stream

Tr Crystal Crk

Primary Dam Type

Earth

Surface Area

8

Hydraulic Height

48

Drainage Area

0.13

Nid Storage

105

Hazard Potential

High

Nid Height

51
       
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.