Early Intake Reservoir Report

Last Updated: December 5, 2025

Early Intake, located in Moccasin, California, is a vital structure owned by the local government and regulated by the Department of Water Resources and Safety of Dams.


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Summary

Built in 1925, this arch-type dam on the Tuolumne River primarily serves the purpose of flood risk reduction but also contributes to hydroelectric power generation and water supply in the region. With a height of 56 feet and a storage capacity of 115 acre-feet, Early Intake plays a crucial role in managing water resources in Tuolumne County.

Despite its age, Early Intake is in fair condition with a low hazard potential, as assessed in September 2017. Regular inspections are conducted, with the most recent one taking place in March 2021 to ensure its structural integrity and safety. The dam's emergency action plan was last revised in October 1992, indicating a proactive approach to emergency preparedness and response. With a history of serving the community for nearly a century, Early Intake stands as a testament to the importance of proper water resource management and infrastructure maintenance in the face of changing climate patterns and environmental challenges.

As a significant component of the San Francisco District's water infrastructure, Early Intake not only provides flood protection but also contributes to the region's renewable energy production and water supply reliability. With its strategic location on the Tuolumne River, this historic dam continues to play a vital role in safeguarding communities downstream and supporting sustainable water management practices. For water resource and climate enthusiasts, Early Intake serves as a tangible example of how infrastructure can adapt to evolving environmental conditions while meeting the diverse needs of society.

Year Completed

1925

Dam Length

262

Dam Height

56

River Or Stream

Tuolumne River

Primary Dam Type

Arch

Surface Area

7

Hydraulic Height

46

Drainage Area

488

Nid Storage

115

Hazard Potential

Low

Nid Height

56
       
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.