Yarnell Debris Basin Reservoir Report

Last Updated: December 5, 2025

Yarnell Debris Basin, located in Los Angeles, California, was completed in 1963 with a primary purpose of debris control along Tr Bull Canyon.


°F

°F

mph

Wind

%

Humidity

Summary

This earth dam stands at a height of 42 feet, providing storage of 77.5 acre-feet and covering a surface area of 10 acres. The basin has a low hazard potential and is deemed to be in satisfactory condition as of the last assessment in September 2017.

Managed by the local government, Yarnell Debris Basin is regulated by the California Department of Water Resources' Safety of Dams division, ensuring that the structure is inspected, permitted, and enforced for compliance with state regulations. Although the dam has not undergone modifications in recent years and lacks certain features like spillways or outlet gates, it serves a crucial role in reducing flood risks in the region. With its close proximity to residential areas, the basin plays a vital role in protecting communities from potential debris flow events during heavy rainfall.

A noteworthy feature of Yarnell Debris Basin is its association with the U.S. Army Corps of Engineers, Los Angeles District, highlighting the collaborative efforts between federal and local agencies in managing water resources and mitigating climate-related risks. With its strategic location and effective debris control measures, Yarnell Debris Basin stands as a testament to the importance of proactive infrastructure in safeguarding against natural disasters and ensuring the resilience of communities in the face of changing environmental conditions.

Year Completed

1963

Dam Length

1290

Dam Height

42

River Or Stream

Tr Bull Canyon

Primary Dam Type

Earth

Surface Area

10

Hydraulic Height

30

Drainage Area

1.87

Nid Storage

77.5

Hazard Potential

Low

Nid Height

42
       
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.