Hj Mills Reclamation Reservoir Report

Last Updated: December 5, 2025

Located in Riverside, California, Hj Mills Reclamation is a vital piece of infrastructure designed for water supply purposes.


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Summary

Completed in 1996, this earth dam stands at a height of 48 feet and boasts a storage capacity of 98 acre-feet. With a surface area of 16 acres and a drainage area of 0.03 square miles, this offstream structure plays a crucial role in water management in the region.

Maintained by the California Department of Water Resources and regulated by the Safety of Dams agency, Hj Mills Reclamation has a significant hazard potential but is currently assessed to be in satisfactory condition. The dam underwent its last inspection in October 2020, with a frequency of one inspection per year. In case of emergencies, there is an Emergency Action Plan (EAP) in place, last revised in December 2018, to ensure swift and coordinated responses to any potential risks or incidents.

With its strategic location and modern design, Hj Mills Reclamation serves as a key component of the water infrastructure in Riverside. As climate change continues to impact water resources, structures like this play an essential role in ensuring a reliable water supply for the community. As enthusiasts of water resources and climate, the details of Hj Mills Reclamation offer a fascinating insight into the intersection of engineering, regulation, and environmental stewardship in managing our precious water sources.

Year Completed

1996

Dam Length

1560

Dam Height

48

River Or Stream

Offstream

Primary Dam Type

Earth

Surface Area

16

Hydraulic Height

45

Drainage Area

0.03

Nid Storage

98

Hazard Potential

Significant

Nid Height

48
       
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.