Stonehenge Lake Dam Reservoir Report
Nearby: Keeven Lake Dam Mueth Lake Dam
Last Updated: December 25, 2025
Stonehenge Lake Dam, located in St.
°F
°F
mph
Wind
%
Humidity
Summary
Clair County, Illinois, stands as a private earth dam nestled along the Prairie Du Long Creek. Built in 2008 with a primary purpose of recreation, this dam boasts a height of 33 feet and a length of 320 feet, offering a serene 18-acre surface area for outdoor enthusiasts to enjoy. The dam's stone core foundation and rock and soil base provide a sturdy structure that supports a maximum storage capacity of 200 acre-feet.
Managed by the Illinois Department of Natural Resources, Stonehenge Lake Dam is state-regulated and regularly inspected to ensure its safety. The dam's uncontrolled spillway, with a width of 60 feet, can handle a maximum discharge of 2846 cubic feet per second, reducing the risk of potential hazards. Despite its significant hazard potential, the dam's moderate risk assessment (3 out of 5) indicates that proper risk management measures are in place, making it a secure and enjoyable destination for water resource and climate enthusiasts to explore.
Year Completed |
2008 |
Dam Length |
320 |
Dam Height |
33 |
River Or Stream |
PRAIRIE DU LONG CREEK |
Primary Dam Type |
Earth |
Surface Area |
18 |
Drainage Area |
4.1 |
Nid Storage |
200 |
Outlet Gates |
None |
Hazard Potential |
Significant |
Foundations |
Rock, Soil |
Nid Height |
33 |
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.
Stonehenge Lake Dam