Patterson Lake Dam Reservoir Report
Last Updated: December 5, 2025
Patterson Lake Dam, located in Clay, Illinois, is a private structure primarily used for recreation purposes.
°F
°F
mph
Wind
%
Humidity
Summary
Built in 1926, this earth dam stands at a height of 31 feet and spans 535 feet in length, with a storage capacity of 309 acre-feet. The dam is situated on the tributary of Dismal Creek and is regulated by the Illinois Department of Natural Resources (IDNR).
With a significant hazard potential and a moderate risk assessment rating, Patterson Lake Dam undergoes inspections every three years to ensure its structural integrity and safety. The dam features an uncontrolled spillway and outlet gates, making it essential for proper management and monitoring. While the condition assessment is currently not available, it is crucial for water resource and climate enthusiasts to stay informed about the risk management measures in place for this recreational dam.
As a key feature in the St. Louis District of Illinois, Patterson Lake Dam offers an opportunity for outdoor enthusiasts to enjoy water-based activities in a picturesque setting. Despite its age, the dam continues to provide valuable recreational opportunities while also serving as a vital structure for water resource management in the region. For those interested in the intersection of water resources and climate, Patterson Lake Dam presents an intriguing case study of balancing recreational use with environmental stewardship and risk management.
Year Completed |
1926 |
Dam Length |
535 |
Dam Height |
31 |
River Or Stream |
TRIB DISMAL CREEK |
Primary Dam Type |
Earth |
Nid Storage |
309 |
Outlet Gates |
Uncontrolled |
Hazard Potential |
Significant |
Foundations |
Unlisted/Unknown |
Nid Height |
31 |
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.
Patterson Lake Dam