Matherville Lagoons Dam Reservoir Report
Last Updated: December 22, 2025
Matherville Lagoons Dam, located in Mercer County, Illinois, is a local government-owned structure regulated by the Illinois Department of Natural Resources.
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Summary
This earth dam, standing at a height of 9 feet, serves primarily for offstream water storage along the Edwards River. With a normal storage capacity of 100 acre-feet and a maximum storage of 120 acre-feet, the dam plays a crucial role in managing water resources in the area.
Despite its modest size, Matherville Lagoons Dam poses a significant hazard potential, as indicated by a high risk assessment rating of 2. However, specific details on its condition assessment are not available. The last inspection in November 2020 revealed no major concerns, but the dam's emergency action plan has not been updated in recent years. With a three-year inspection frequency and a designated emergency contact protocol, ongoing risk management measures are in place to ensure the safety and integrity of the dam.
Water resource and climate enthusiasts can appreciate Matherville Lagoons Dam as a vital infrastructure for water storage and management in Mercer County. Its location along the Edwards River, coupled with state regulatory oversight and high hazard potential, highlights the importance of monitoring and maintaining this earth dam to mitigate risks and safeguard surrounding communities and ecosystems from potential water-related threats.
Dam Height |
9 |
River Or Stream |
EDWARDS RIVER - OFFSTREAM |
Primary Dam Type |
Earth |
Nid Storage |
120 |
Hazard Potential |
Significant |
Foundations |
Soil |
Nid Height |
9 |
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.
Matherville Lagoons Dam