Puddingstone Reservoir Report

Last Updated: December 13, 2025

Located in Covina, California, Puddingstone, also known as Puddingstone Reservoir, is a local government-owned dam on Walnut Creek.


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Summary

Built in 1928 for flood risk reduction, this earth dam stands at a height of 147 feet and has a storage capacity of 16,342 acre-feet. With a surface area of 490 acres and a drainage area of 33.6 square miles, Puddingstone plays a crucial role in managing water resources in Los Angeles County.

Managed by the Department of Water Resources and regulated by the Safety of Dams agency, Puddingstone is subject to regular inspections and enforcement actions to ensure its structural integrity and safety. The dam has a high hazard potential but was found to be in satisfactory condition during the last assessment in September 2017. In case of emergencies, the dam is equipped with an Emergency Action Plan, although its last revision was in January 2018.

For water resource and climate enthusiasts, Puddingstone serves as a fascinating example of how infrastructure can effectively mitigate flood risks while providing essential water supply services. Its location, design, and operational history make it a valuable asset in the region's water management efforts, demonstrating the importance of proper regulation and maintenance for the safety of communities downstream.

Year Completed

1928

Dam Length

2698

Dam Height

147

River Or Stream

Walnut Creek

Primary Dam Type

Earth

Surface Area

490

Hydraulic Height

135

Drainage Area

33.6

Nid Storage

16342

Hazard Potential

High

Nid Height

147
       
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.