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Mt. Gilead Lake Lower and Upper Dams

Location and Description

Conceptual design of completed dam.

Mt. Gilead Lake Lower Dam is part of Mt. Gilead State Park located off of State Route 95 in Morrow County. The dam was built in 1930 and has a maximum height of 20 feet. It also has a 90-foot-long concrete spillway that discharges water into Whetstone Creek. As a Class I high-hazard potential structure, a sudden failure of the Mt. Gilead Lake Lower Dam likely would result in the structural collapse of at least one residence or one commercial or industrial business and probable loss of human life. (Hazard ratings refer to the consequences of dam failure, not the dam's condition.)

Click the Status tab above for construction photos and updates.


Click here for more about the Dam Risk Reduction Program.

dam problem areas

dam problem areas

dam problem areas

dam problem areas

Dow Lake Dam: Statistics

  • Maximum Embankment Height: 20 feet
  • Length of Dam: 525 feet
  • Crest Width: 12 feet
  • Reservoir Surface Area At Top Of Dam: 14 acres
  • Storage Capacity at Principal Spillway Elevation: 38-acre feet = 12,382,300 gallons
  • Principal Spillway Type: 90' long concrete ogee weir
  • Emergency Spillway: None
  • Principal Spillway Crest Elevation: 1105 feet (msl)
  • Reservoir Surface Area at Principal Spillway: 11.4 acres
  • Lake Drains: 16-inch HDPE siphon
  • Dam Classification: Class I
  • Lake Constructed: 1930
  • Lake Inflow: Sams Creek
  • Total Drainage Area To Lake: 8.67 square miles
  • Lake Outflow: Whetstone Creek
  • Counties: The site is located in Morrow County at Mt. Gilead State Park
  • Communities: Mt. Gilead

Safety Issues

Mt. Gilead Lake Lower Dam currently has deficiencies that must be addressed to bring it into compliance with state dam safety standards. The deficiencies include insufficient storage-discharge capacity and seepage. There are additional concerns regarding the instability of the severely deteriorated concrete spillway and the entire dam embankment, along with concerns about the presence of trees and brush on the dam. ODNR previously contracted with Jobes & Henderson, and SME, to provide investigations and preliminary design alternatives. These investigations of the dam structure revealed the concrete spillway is deteriorated and has a very low safety level.

Risk Reduction

ODNR is contracted with Moser Construction to complete dam improvements at Mt. Gilead State Park. Work to modify the earthen embankment (Lower Dam) and construct a new spillway began in Summer, 2016 which required draining the lake and demolition of the existing dam structure. The extensive scope of work also includes improvements to the Upper Dam as well as the outflow channel below the Lower Dam and new spillway. Project completion is scheduled for Fall, 2017; it will result in a structure that meets dam safety requirements.

Long Term Plan

Operation, maintenance and routine inspections of the dam will continue by Ohio State Parks staff. Each year, engineers and staff with the Ohio Dam Safety Program, which is part of ODNR’s Division of Water Resources, conduct more than 350 detailed inspections of dams statewide on a five-year schedule that include Mt. Gilead Dam and other regulated structures owned by the State of Ohio as well as privately-owned structures. An emergency action plan will be revised and shared with local emergency management officials once it is completed.


News Releases

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Media Coverage

Supporting Documents


To request more information you may write to:

Ohio Department of Natural Resources
Dam Risk Reduction Project
2045 Morse Road, Building E-3
Columbus, Ohio 43229

or send an email communication to