Willow Hill Reservoir Reservoir Report

Last Updated: December 5, 2025

Willow Hill Reservoir, located in Folsom, California, is a vital water supply facility owned by the local government.


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Summary

This reservoir is regulated by the Department of Water Resources (DWR) and falls under the jurisdiction of the state, ensuring proper permitting, inspection, and enforcement protocols are in place. With a primary purpose of water supply, Willow Hill Reservoir serves multiple uses including irrigation and tailings management.

This Earth-type dam stands at a height of 24 feet and has a hydraulic height of 20 feet, with a storage capacity of 125 acre-feet. The reservoir covers a surface area of 13 acres and has a drainage area of 0.06 square miles, offering a crucial water source for the region. Despite being classified as having a high hazard potential, Willow Hill Reservoir is currently assessed to be in fair condition as of September 2017, with regular inspections and emergency action plans in place to ensure the safety and functionality of the structure.

With its strategic location along the Tr American River, Willow Hill Reservoir plays a key role in water resource management in Sacramento County. As climate change continues to impact water availability and quality, reservoirs like Willow Hill are essential for ensuring a reliable water supply for agricultural, urban, and industrial needs in the region. Through diligent maintenance and risk management measures, Willow Hill Reservoir stands as a critical infrastructure supporting the community's water security and resilience in the face of changing environmental conditions.

Dam Length

240

Dam Height

24

River Or Stream

Tr American Rv

Primary Dam Type

Earth

Surface Area

13

Hydraulic Height

20

Drainage Area

0.06

Nid Storage

125

Hazard Potential

High

Nid Height

24
       
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.