Hall Mill Dam Reservoir Report

Last Updated: December 5, 2025

Hall Mill Dam, also known as Lake Fulmor Dam, is a federal-owned structure located in Riverside, California.


°F

°F

mph

Wind

%

Humidity

Summary

Completed in 1949, this earth dam stands at a height of 40 feet and stretches 220 feet in length. It serves a primary purpose other than water storage and is classified as having a high hazard potential. Despite its age, the condition of the dam is currently not rated, and it undergoes inspections annually to ensure its safety.

Managed by the Forest Service, Hall Mill Dam does not fall under state regulation or jurisdiction. It features an uncontrolled spillway and is constructed with a stone core and built on rock and soil foundations. The dam's risk assessment indicates a moderate level of risk, with no emergency action plan in place as of the last data update in May 2021. With its captivating history and design, Hall Mill Dam stands as a notable landmark for water resource and climate enthusiasts interested in exploring the intersection of infrastructure and environmental conservation in California's diverse landscape.

Year Completed

1949

Dam Length

220

Dam Height

40

Primary Dam Type

Earth

Structural Height

40

Hazard Potential

High

Foundations

Rock, Soil

Nid Height

40
       
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.