Chino Ranch #1 Reservoir Report

Last Updated: December 5, 2025

Chino Ranch #1, also known as Arnold Reservoir, is a local government-owned water storage facility located in Brea, California.


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Summary

Built in 1918, this earth dam structure stands at a height of 22 feet and has a hydraulic height of 17.5 feet. With a storage capacity of 137 acre-feet, this reservoir primarily serves the purpose of water supply for irrigation and other needs in the area.

Managed by the California Department of Water Resources, Chino Ranch #1 is regulated, permitted, inspected, and enforced by state authorities to ensure its safety and functionality. The dam is situated along the Tonner Canyon Creek in San Bernardino County and has a significant hazard potential. Despite this, the condition assessment deemed it satisfactory as of September 2017, with regular inspections conducted to monitor its structural integrity.

The reservoir covers a surface area of 20 acres and has a maximum discharge capacity, although specific spillway details are not provided in the data. With its rich history and crucial role in water resource management, Chino Ranch #1 stands as a key infrastructure for water supply in the region, highlighting the importance of sustainable practices and climate resilience in maintaining such critical water resources.

Year Completed

1918

Dam Length

460

Dam Height

22

River Or Stream

Tonner Canyon Cr

Primary Dam Type

Earth

Surface Area

20

Hydraulic Height

17.5

Nid Storage

137

Hazard Potential

Significant

Nid Height

22
       
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.