Forest Lake Dam Reservoir Report

Last Updated: December 5, 2025

Forest Lake Dam, located in Hawthorne Woods, Illinois, was completed in 1935 for the primary purpose of recreation.


°F

°F

mph

Wind

%

Humidity

Summary

The dam is classified as an Earth dam with a height of 11 feet and a length of 125 feet, creating a reservoir with a normal storage capacity of 457 acre-feet. The dam is situated on a tributary of Indian Creek and is under the jurisdiction of the Illinois Department of Natural Resources.

With a high hazard potential and moderate risk assessment, Forest Lake Dam is subject to state regulation, inspection, and enforcement to ensure public safety. The dam features an uncontrolled spillway with a width of 175 feet and a maximum discharge of 1684 cubic feet per second. Despite its age, the dam's condition assessment is not available, indicating the need for ongoing monitoring and maintenance to mitigate risks associated with its structural integrity.

In the event of an emergency, there are no outlet gates or Emergency Action Plan (EAP) prepared for Forest Lake Dam. While the dam provides recreational opportunities and serves as a vital water resource in the area, continued evaluation and risk management measures will be crucial to safeguard the surrounding community and the environment in the face of changing climate conditions.

Year Completed

1935

Dam Length

125

Dam Height

11

River Or Stream

TRIB INDIAN CREEK

Primary Dam Type

Earth

Surface Area

38

Drainage Area

0.7

Nid Storage

561

Outlet Gates

None

Hazard Potential

High

Foundations

Unlisted/Unknown

Nid Height

11
       
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.