Wonder Lake Sediment Dewatering Facility Dam Reservoir Report

Last Updated: December 5, 2025

The Wonder Lake Sediment Dewatering Facility Dam in Wonder Lake, Illinois, is a privately owned Earth dam completed in 2014 with a height of 22 feet and a length of 2300 feet.


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Summary

The dam serves a unique purpose as a sediment dewatering facility, with a storage capacity of 300 acre-feet and a surface area of 40 acres. The dam is regulated by the Illinois Department of Natural Resources and undergoes regular inspections to ensure its safety and compliance with state regulations.

Located on Galt Creek offstream, the Wonder Lake Dam has a controlled spillway with a width of 4 feet and a hazard potential rated as high. The risk assessment for the dam indicates a very high risk level, emphasizing the importance of proper risk management measures. While the condition assessment of the dam is currently not available, emergency action plans have been prepared in the past to address any potential hazards or emergencies that may arise.

Managed by HDR Engineering, Inc., the Wonder Lake Sediment Dewatering Facility Dam is a significant structure in McHenry County, Illinois, contributing to water resource management and climate resilience efforts in the region. With its unique purpose and high-risk potential, the dam plays a crucial role in protecting the surrounding community and environment from potential flooding and sediment-related issues.

Year Completed

2014

Dam Length

2300

Dam Height

22

River Or Stream

GALT CREEK - OFFSTREAM

Primary Dam Type

Earth

Surface Area

40

Nid Storage

300

Outlet Gates

None

Hazard Potential

High

Foundations

Soil

Nid Height

22
       
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.