Ylsa Lake Dam Reservoir Report
Last Updated: December 23, 2025
Ylsa Lake Dam, located in Monroe County, Illinois, was completed in 1995 and stands at a impressive height of 20 feet with a length of 370 feet.
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Summary
The dam serves primarily for recreational purposes, offering visitors a serene environment to enjoy the surrounding beauty. With a storage capacity of 22 acre-feet and a normal storage of 15 acre-feet, the dam provides a vital resource for the local community.
Managed by a private owner, the dam is regulated by the Illinois Department of Natural Resources (IDNR) and undergoes regular inspections to ensure its safety and structural integrity. The dam is situated on TRIB ROCKHOUSE CREEK and is equipped with an uncontrolled spillway, with a maximum discharge capacity of 31 cubic feet per second. Despite its significant hazard potential, the dam's risk assessment is rated as moderate, indicating that appropriate risk management measures are in place.
Climate and water resource enthusiasts will appreciate the engineering behind Ylsa Lake Dam, which combines stone core and soil foundation in its earth dam structure. The dam's location offers a unique opportunity to observe the intersection of human infrastructure with natural landscapes, providing a valuable case study for understanding the complexities of managing water resources in a changing climate. With its picturesque setting and important role in local recreation, Ylsa Lake Dam showcases the intersection of environmental stewardship and community engagement in water resource management.
Year Completed |
1995 |
Dam Length |
370 |
Dam Height |
20 |
River Or Stream |
TRIB ROCKHOUSE CREEK |
Primary Dam Type |
Earth |
Surface Area |
2 |
Drainage Area |
0.06 |
Nid Storage |
22 |
Outlet Gates |
None |
Hazard Potential |
Significant |
Foundations |
Soil |
Nid Height |
20 |
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.
Ylsa Lake Dam