Pit #1 Diversion Reservoir Report

Last Updated: December 5, 2025

Pit #1 Diversion, located in Fall River Mills, California, is a privately owned structure that plays a crucial role in flood risk reduction and hydroelectric power generation along the Fall River.


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Summary

Completed in 1922, this gravity dam stands at a height of 15 feet and has a storage capacity of 50 acre-feet. With a low hazard potential and a satisfactory condition assessment, Pit #1 Diversion is regulated and inspected by the California Department of Water Resources to ensure its safety and effectiveness in managing water resources in the region.

Despite its age, Pit #1 Diversion continues to serve its primary purpose of flood risk reduction, showcasing the enduring engineering ingenuity that went into its design and construction nearly a century ago. With a drainage area of 676 square miles and a surface area of 9 acres, this dam plays a significant role in regulating water flow and mitigating potential flood events in the surrounding area. Additionally, its proximity to the Fall River makes it a vital component of the local water infrastructure, highlighting its importance in maintaining water security and ecological balance in the region.

As a key feature in the water management system of Shasta County, Pit #1 Diversion stands as a testament to the enduring impact of early 20th-century engineering on modern-day water resource management. With its historical significance, functional efficiency, and ongoing regulatory oversight, this gravity dam continues to play a crucial role in safeguarding communities and ecosystems against the threat of flooding while also supporting sustainable hydroelectric power generation in the region.

Year Completed

1922

Dam Length

600

Dam Height

15

River Or Stream

Fall River

Primary Dam Type

Gravity

Surface Area

9

Hydraulic Height

12

Drainage Area

676

Nid Storage

50

Hazard Potential

Low

Nid Height

15
       
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.