Big Santa Anita Reservoir Report

Last Updated: December 5, 2025

Big Santa Anita is a crucial dam located in Sierra Madre, California, serving as a vital component for flood risk reduction, irrigation, and water supply in the region.


°F

°F

mph

Wind

%

Humidity

Summary

Built in 1927, this arch-type dam stands at a height of 225 feet, with a hydraulic height of 127 feet and a length of 612 feet, providing a storage capacity of 858 acre-feet. Situated on the Tr Rio Hondo river, the dam covers a surface area of 5 acres and drains a watershed area of 10.8 square miles, making it a significant structure in managing water resources in Los Angeles County.

Despite its age, the dam is in satisfactory condition according to a 2017 assessment, with a high hazard potential due to its critical role in flood risk reduction. The dam is under the jurisdiction of the California Department of Water Resources and is subject to regular inspections, permitting, and enforcement to ensure its structural integrity and safety. The surrounding community relies on Big Santa Anita for protection against flooding events and as a vital source of water for irrigation and supply, highlighting the importance of maintaining and monitoring this key infrastructure in the face of changing climate conditions.

With a history of serving the local community for over nine decades, Big Santa Anita continues to play a vital role in water resource management and climate resilience efforts in Southern California. As climate change brings about more frequent and intense weather events, the dam's role in flood risk reduction becomes increasingly crucial. By ensuring the ongoing maintenance and monitoring of this essential infrastructure, stakeholders can better prepare for and mitigate the impacts of extreme weather events, safeguarding both lives and property in the region.

Year Completed

1927

Dam Length

612

Dam Height

225

River Or Stream

Tr Rio Hondo

Primary Dam Type

Arch

Surface Area

5

Hydraulic Height

127

Drainage Area

10.8

Nid Storage

858

Hazard Potential

High

Nid Height

225
       
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.