Lake Cohasset Dam Reservoir Report

Last Updated: December 5, 2025

Lake Cohasset Dam, located in Mahoning, Ohio, was completed in 1897 and serves as a vital recreation spot for water resource and climate enthusiasts.


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Summary

The dam, with a height of 25 feet and a length of 190 feet, provides a storage capacity of 373 acre-feet and covers a surface area of 28 acres. The dam is situated on Mill Creek and falls under the regulatory jurisdiction of the Department of Natural Resources in Ohio.

Despite its historical significance and recreational value, Lake Cohasset Dam has been assessed as being in poor condition with a significant hazard potential. The last inspection in 2016 revealed the dam's deteriorating state, prompting concerns about its structural integrity and safety. The dam has not undergone any modifications in recent years, highlighting the need for immediate attention and potential risk management measures to ensure public safety and environmental protection.

With the dam showing signs of wear and a poor condition assessment, stakeholders and authorities, including Congressman Tim Ryan, must collaborate to address the dam's maintenance and safety concerns. Given its importance for recreation and water resource management, proactive measures such as regular inspections, maintenance, and potential rehabilitation efforts are crucial to safeguarding Lake Cohasset Dam and its surrounding environment for future generations of water resource and climate enthusiasts.

Year Completed

1897

Dam Length

190

Dam Height

25

River Or Stream

MILL CREEK

Primary Dam Type

Masonry

Surface Area

28

Drainage Area

74.2

Nid Storage

373

Hazard Potential

Significant

Nid Height

25
       
Seasonal Comparison

Weather Forecast

Dam Data Reference

Condition Assessment

Satisfactory
No 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

High
Dams 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.