Yellow Head Marsh Dam Reservoir Report

Last Updated: December 5, 2025

Yellow Head Marsh Dam, also known as Moraine Hills Mitigation Dam, is a state-owned structure located in McHenry, Illinois.


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Summary

Built in 1990 by Wells Engineering, this earth dam stands at a height of 7 feet and stretches for 1000 feet along the TRIB FOX RIVER. With a storage capacity of 579 acre-feet, the dam's primary purpose is listed as "Other", with a low hazard potential and a moderate risk assessment rating.

Managed by the Illinois Department of Natural Resources, the Yellow Head Marsh Dam plays a crucial role in regulating water flow along the Fox River and mitigating potential flood risks in the surrounding area. Despite its relatively low hazard potential, the dam is subject to regular state inspection, permitting, and enforcement measures to ensure its structural integrity and operational efficiency. The dam's uncontrolled spillway, with a width of 24 feet, allows for a maximum discharge of 400 cubic feet per second during times of high water flow.

For water resource and climate enthusiasts, the Yellow Head Marsh Dam presents an intriguing case study in dam management and risk assessment. Its location near Ferndale, Illinois, serves as a vital checkpoint in the region's water infrastructure, demonstrating the importance of proactive maintenance and monitoring practices in safeguarding against potential hazards and ensuring the sustainable use of water resources for future generations.

Year Completed

1990

Dam Length

1000

Dam Height

7

River Or Stream

TRIB FOX RIVER

Primary Dam Type

Earth

Nid Storage

579

Outlet Gates

None

Hazard Potential

Low

Foundations

Unlisted/Unknown

Nid Height

7
       
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.