Williamson No. 1 Reservoir Report

Last Updated: December 5, 2025

Williamson No.


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Summary

1 is a significant dam located in Shingle Springs, California, along the Tr Weber Creek. Completed in 1926, this earth dam stands at a height of 42 feet and has a hydraulic height of 34.4 feet. The primary purpose of Williamson No. 1 is for water supply, serving irrigation, recreation, and water supply needs in the area. With a storage capacity of 117 acre-feet and a surface area of 11 acres, this dam plays a crucial role in water resource management in El Dorado County.

Despite its historical significance, Williamson No. 1 is currently assessed as being in poor condition, with a significant hazard potential. The dam is privately owned and regulated by the California Department of Water Resources, Safety of Dams division. Regular inspections are conducted, with the last assessment completed in February 2021. Efforts are underway to address the condition of the dam and ensure that it continues to fulfill its important role in water management and supply in the region.

As a key infrastructure for water supply, Williamson No. 1 is a vital resource for the local community and surrounding areas. With its age and current condition in mind, ongoing maintenance and potential upgrades are essential to ensure the safety and reliability of this dam for the future. Climate and water resource enthusiasts will find interest in the history and current status of Williamson No. 1, as well as the efforts being made to address its condition and maintain its important role in the region's water supply system.

Year Completed

1926

Dam Length

240

Dam Height

42

River Or Stream

Tr Weber Creek

Primary Dam Type

Earth

Surface Area

11

Hydraulic Height

34.4

Drainage Area

1.3

Nid Storage

117

Hazard Potential

Significant

Nid Height

42
       
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.