Greenwood Lake Dam Reservoir Report
Last Updated: December 16, 2025
Greenwood Lake Dam, located in Fisher-Offstream, Illinois, was completed in 1960 and stands at a height of 15 feet with a length of 900 feet.
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Summary
The dam's primary purpose is for recreation, offering a storage capacity of 114 acre-feet and a normal storage level of 65 acre-feet. While its hazard potential is considered significant, the dam has not undergone a recent condition assessment.
Managed by a private owner, Greenwood Lake Dam is regulated by the Illinois Department of Natural Resources (IDNR) and is subject to regular state inspections and enforcement. The dam, classified as an earth dam with a buttress core type, features an uncontrolled spillway and outlet gates. Despite its moderate risk rating, the dam's emergency action plan (EAP) status and risk management measures are currently unavailable.
Situated along the Hillsbury Slough-Offstream waterway in Champaign County, Greenwood Lake Dam offers recreational opportunities while facing regulatory oversight and maintenance challenges. With its scenic location and historical significance, the dam serves as an essential component of the local water resource infrastructure, prompting ongoing monitoring and risk assessment to ensure public safety and environmental protection in the region.
Year Completed |
1960 |
Dam Length |
900 |
Dam Height |
15 |
River Or Stream |
HILLSBURY SLOUGH-OFFSTREAM |
Primary Dam Type |
Earth |
Nid Storage |
114 |
Outlet Gates |
Uncontrolled |
Hazard Potential |
Significant |
Foundations |
Unlisted/Unknown |
Nid Height |
15 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Dam Data Reference
Condition Assessment
SatisfactoryNo 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
HighDams 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.
Greenwood Lake Dam