Santa Anita Debris Basin Reservoir Report

Last Updated: December 5, 2025

Santa Anita Debris Basin, located in Monrovia, California, along the Santa Anita Wash, serves as a crucial structure for debris control and flood risk reduction in the region.


°F

°F

mph

Wind

%

Humidity

Summary

Built in 1960, this earth dam stands at a height of 56 feet and has a hydraulic height of 34.7 feet. With a storage capacity of 116 acre-feet and covering a surface area of 9 acres, the basin plays a vital role in managing the drainage area of 12.5 square miles.

Owned and regulated by local government authorities, Santa Anita Debris Basin undergoes regular state inspections, enforcement, and permitting to ensure its functionality and safety. The dam has been assessed to be in fair condition, with a low hazard potential. In case of emergencies, the facility has an Emergency Action Plan (EAP) in place, although details about the plan's last revision and adherence to guidelines are currently unavailable.

Overall, Santa Anita Debris Basin stands as an essential infrastructure for protecting the surrounding areas from debris flow and flood risks. Its strategic location, efficient design, and regular maintenance make it a key player in water resource management and climate resilience efforts in Los Angeles County, California.

Year Completed

1960

Dam Length

955

Dam Height

56

River Or Stream

Santa Anita Wash

Primary Dam Type

Earth

Surface Area

9

Hydraulic Height

34.7

Drainage Area

12.5

Nid Storage

116

Hazard Potential

Low

Nid Height

56
       
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.