Butt Valley Reservoir Report

Last Updated: December 5, 2025

Butt Valley, located in Little Haven, California, is a private hydroelectric dam on Butt Creek completed in 1924.


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Summary

With a height of 70 feet and a length of 1520 feet, this earth dam provides a storage capacity of nearly 50,000 acre-feet, serving as a vital water resource in the region. The dam has a high hazard potential and is regulated by the Federal Energy Regulatory Commission, ensuring its safety and compliance with inspection and enforcement measures.

The dam's primary purpose is hydroelectric power generation, with a normal storage capacity of 49,800 acre-feet and a maximum discharge of 30,000 cubic feet per second. Its uncontrolled spillway, with a width of 150 feet, helps manage excess water flow during peak periods. Despite its age, Butt Valley Dam continues to be a significant feature in the region's water infrastructure, supporting both water supply and energy generation needs. Climate and water resource enthusiasts are drawn to the dam's historical significance and its role in sustainable water management practices.

Year Completed

1924

Dam Length

1520

Dam Height

70

River Or Stream

Butt Creek

Primary Dam Type

Earth

Surface Area

1600

Hydraulic Height

70

Drainage Area

83.5

Nid Storage

49897

Structural Height

80

Hazard Potential

High

Nid Height

80
       
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.