St. Henry Wwt Lagoon Reservoir Report
Last Updated: December 19, 2025
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Summary
Henry Wwt Lagoon in Mercer County, Ohio, is a vital water resource managed by the local government. Designed by Arnold N. Stemen, P.E., this wastewater treatment lagoon serves the primary purpose of managing tailings and was completed in 1988. With a dam height of 26.5 feet and a storage capacity of 501 acre-feet, it plays a significant role in water management within the Coldwater Creek watershed.
The St. Henry Wwt Lagoon is state-regulated by the Ohio Department of Natural Resources, ensuring that it meets strict standards for inspection, enforcement, and permitting. Despite its significant hazard potential, the lagoon's condition is assessed as satisfactory, with regular inspections conducted to ensure its ongoing safety and functionality. The lagoon also has emergency action plans in place, demonstrating a commitment to preparedness and risk management in the event of any unforeseen events.
Located in Coldwater, Ohio, the St. Henry Wwt Lagoon is a critical piece of infrastructure in the region's water management system. With a surface area of 45.4 acres and a drainage area of 0.07 square miles, this lagoon plays a crucial role in controlling discharge and ensuring water quality in the Coldwater Creek watershed. Climate and water resource enthusiasts would find St. Henry Wwt Lagoon to be a fascinating example of how local governments work to protect and manage water resources for the benefit of their communities.
Year Completed |
1988 |
Dam Length |
5540 |
Dam Height |
26.5 |
River Or Stream |
COLDWATER CREEK - OFFSTREAM |
Primary Dam Type |
Earth |
Surface Area |
45.4 |
Drainage Area |
0.07 |
Nid Storage |
501 |
Hazard Potential |
Significant |
Nid Height |
27 |
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.
St. Henry Wwt Lagoon