Johnson-French Lake is Site #5 for Margaret Creek Conservancy District (MCCD). Site #5 has a floodwater-retarding dam constructed of compacted earth fill. This structure is classified by ODNR as a hazard Class III dam. It is 31 feet high and controls the runoff from 1.7 square miles. A permanent pool of 8.3 surface acres provides sediment storage. The principal spillway is a reinforced concrete pipe system, which maintains the normal pool level and regulates the passage of flood flows. It consists of an NRCS standard covered top riser with trash rack, a 30-inch diameter reinforced concrete pipe, and a concrete stilling basin as an outlet structure. The emergency spillway is 120 feet wide and is designed to safely pass 6.75 inches of rainfall occurring in a 6-hour period. The dam was also designed to pass 13.0 inches of rain occurring in a 6-hour period without overtopping the dam. A 12-inch diameter lake drain allows the lake to be lowered for maintenance. The primary purpose for Site #5 is flood risk reduction.

Drainage Area...............................................1,062 Acres

Total Storage..................................................456 Acre Feet

Floodwater Retarding Storage.............................173 Acre Feet

Water Surface Area.....................................8.3 Acres

Height Of Dam........................................29 Feet

Volume Of Fill.......................................................46,600 Cubic Yards

Built in 1969 under The Watershed Protection And Flood Prevention Act by Margaret Creek Conservancy District
, the 
Athens County Board of Commissioners and the 
Athens Soil and Water Conservation District
 with assistance of 
Soil Conservation Service, U.S. Dept. Of Agriculture
.

Constructed under PL566