Preston Reservoir Report

Last Updated: December 5, 2025

Preston dam, located in Amador County, California, is a vital structure managed by the public utility for water supply purposes.


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Summary

Built in 1949, this earth dam stands at a height of 40 feet and has a storage capacity of 268 acre-feet on Tr Mule Creek. With a high hazard potential, the dam is under the regulatory oversight of the Department of Water Resources and Safety of Dams.

Despite its satisfactory condition assessment as of September 2017, regular inspections are conducted to ensure its structural integrity and safety. The dam plays a crucial role in flood risk reduction, irrigation, and water supply for the surrounding areas. Managed by the Natural Resources Conservation Service, Preston dam is a significant component in the water resource infrastructure of the region, contributing to the overall water management efforts in California.

With its strategic location and operational efficiency, Preston dam serves as a testament to effective water resource management in the face of changing climate patterns. As climate enthusiasts and water resource specialists continue to monitor and analyze the impact of climate change on water availability and infrastructure, structures like Preston dam play a pivotal role in ensuring water security for the community amidst evolving environmental challenges.

Year Completed

1949

Dam Length

647

Dam Height

40

River Or Stream

Tr Mule Creek

Primary Dam Type

Earth

Surface Area

17

Hydraulic Height

35

Drainage Area

0.12

Nid Storage

268

Hazard Potential

High

Nid Height

40
       
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.