Pit No. 4 Diversion Reservoir Report

Last Updated: December 5, 2025

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Summary

4 Diversion is a private-owned dam located in Big Bend, California, along the scenic Pit River. This concrete dam was completed in 1927 and stands at an impressive height of 110 feet, with a hydraulic height of 67 feet. The primary purpose of this hydroelectric structure is evident in its design and operation, serving as a vital source of renewable energy in the region.

With a maximum discharge capacity of 77,000 cubic feet per second and a controlled spillway width of 136 feet, Pit No. 4 Diversion is equipped to manage high water levels and mitigate potential flood risks. This dam plays a crucial role in water resource management, providing storage capacity of 1,970 acre-feet and serving a drainage area of 4,643 square miles. Despite its age, the dam is regularly inspected and regulated by both state and federal agencies to ensure its structural integrity and operational safety.

The high hazard potential and very high risk assessment of Pit No. 4 Diversion highlight the importance of effective risk management and emergency preparedness measures in place. With its historical significance and continued contribution to hydroelectric power generation, this dam serves as a testament to the intersection of water resource management, climate resilience, and sustainable energy production in California.

Year Completed

1927

Dam Length

415

Dam Height

110

River Or Stream

Pit River

Primary Dam Type

Concrete

Surface Area

105

Hydraulic Height

67

Drainage Area

4643

Nid Storage

1970

Structural Height

110

Outlet Gates

Drum - 2, Tainter (radial) - 1

Hazard Potential

High

Nid Height

110
       
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.