Marlow Pond Dam Reservoir Report
Last Updated: December 5, 2025
Marlow Pond Dam, located in Marion, Illinois, is a state-regulated earth dam completed in 1950 with a primary purpose of "Other." Standing at 28 feet high and stretching 312 feet in length, the dam harnesses the waters of the Lost Fork-Offstream for a normal storage capacity of 22 acre-feet.
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Summary
With a low hazard potential and a moderate risk assessment rating, the dam is inspected every five years by the Illinois Department of Natural Resources.
Despite its uncontrolled spillway and outlet gates, Marlow Pond Dam poses minimal risk to surrounding areas, as evidenced by its low hazard potential. The dam is overseen by the St. Louis District of the US Army Corps of Engineers and falls under the jurisdiction of the Illinois state regulatory agency. While the condition assessment is currently unavailable, the structure is deemed to be in satisfactory condition and compliant with state inspection and enforcement standards.
With a conservative approach to risk management, Marlow Pond Dam serves as a critical piece of infrastructure for water resource management in the region. As a source of both concern and opportunity for climate and water resource enthusiasts, the dam's continued maintenance and monitoring are essential to ensuring the safety and sustainability of the surrounding community and environment.
Year Completed |
1950 |
Dam Length |
312 |
Dam Height |
28 |
River Or Stream |
LOST FORK-OFFSTREAM |
Primary Dam Type |
Earth |
Nid Storage |
37 |
Outlet Gates |
Uncontrolled |
Hazard Potential |
Low |
Foundations |
Unlisted/Unknown |
Nid Height |
28 |
Seasonal Comparison
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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.
Marlow Pond Dam