High Hill Farms Dam Reservoir Report

Last Updated: December 13, 2025

High Hill Farms Dam, located in Algonquin, Illinois, was completed in 1977 by MACKIE CONSULTANTS and serves as a critical flood risk reduction infrastructure on the Rat Creek.


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Summary

The dam is of Earth type with a height of 23 feet and a length of 575 feet, providing a storage capacity of 76 acre-feet. With a maximum discharge capacity of 600 cubic feet per second, the dam plays a crucial role in managing floodwaters and protecting the surrounding areas from potential inundation.

Managed by the local government and regulated by the Illinois Department of Natural Resources, High Hill Farms Dam has a high hazard potential due to its proximity to residential and commercial areas. Despite the lack of available condition assessment data, the dam's emergency action plan was last revised in 1994, indicating the need for updated risk management measures and guidelines. The dam's moderate risk assessment highlights the importance of regular inspections and maintenance to ensure its structural integrity and effectiveness in flood control.

As climate change continues to impact water resources and weather patterns, the significance of High Hill Farms Dam in mitigating flood risks and protecting communities in McHenry County, Illinois, becomes increasingly evident. With its strategic location and design features, the dam stands as a vital asset in the region's resilience against extreme weather events and underscores the critical role of infrastructure in adapting to a changing climate.

Year Completed

1977

Dam Length

575

Dam Height

23

River Or Stream

RAT CREEK

Primary Dam Type

Earth

Nid Storage

76

Outlet Gates

None

Hazard Potential

High

Foundations

Unlisted/Unknown

Nid Height

23
       
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.