Hunters Run Structure No. 9 Reservoir Report

Last Updated: December 5, 2025

Hunters Run Structure No.


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Summary

9, also known as Rock Mill Lake, is a vital Earth dam located in Fairfield, Ohio, designed by USDA NRCS in 1959 for flood risk reduction along the Hocking River. This structure is state-regulated and maintained by the Department of Natural Resources, with a high hazard potential due to its 76 feet height and 1010 feet length. The dam has a normal storage capacity of 158 acre-feet, serving a drainage area of 7.14 square miles.

With a fair condition assessment as of the last inspection in May 2017, Hunters Run Structure No. 9 poses a moderate risk level (3) and undergoes inspections every 5 years. Despite the uncontrolled spillway type and outlet gates, the dam has a maximum discharge capacity of 18,127 cubic feet per second, ensuring effective flood risk reduction measures. The structure's location in Hooker, Ohio, highlights its importance in protecting the surrounding area from potential inundation events, showcasing the collaboration between local government and the Natural Resources Conservation Service in safeguarding water resources and mitigating climate-related risks.

Year Completed

1959

Dam Length

1010

Dam Height

76

River Or Stream

HOCKING RIVER

Primary Dam Type

Earth

Surface Area

19.8

Drainage Area

7.14

Nid Storage

2920

Outlet Gates

Uncontrolled

Hazard Potential

High

Foundations

Soil

Nid Height

76
       
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.