FREDERICKTOWN — Fifteen minutes north of Mount Vernon, just northwest of Fredericktown and southeast of the tiny village of Batemantown, lies a recreational treasure of which many folks are unaware. To the U.S. Army Corps of Engineers, which built it, it is known as the North Branch of Kokosing River dam, lake and campground. Locally, it’s referred to as Kokosing Lake or Kokosing Reservoir, and it’s a high point of Knox County.
The dam was built in response to the January 1959 flood, which wreaked havoc in the county. Congressman John Ashbrook, Ohio’s representative at that time, was instrumental in convincing the U.S. Army Corps of Engineers to build the dam for control of the often-overflowing North Branch of the river.
And it worked. According to James Schray, senior water management specialist with the Huntington District of the corps in West Virginia, the dam — authorized in 1962 and completed in 1972 for flood control, general recreation and wildlife and fish conservation — has prevented an estimated $1,775,000 in property damage from its construction until the year 2000.
The dam is 1,400 feet in length, said Schray, and 70 1/2 feet from bottom to top. He said the dam’s top is 1,169 feet above sea level, and the lake’s surface is 1,121 feet above sea level. Standing atop the dam, 48 feet above the water, visitors can look back at Waterford Road, but in all other directions, the lake, the spillway and the surrounding wildland spread out far below.
The lake covers 154 acres. Schray said it stores a volume of water measuring 1,043 acre-feet, equal to 340 million gallons of water. Fishermen and fisherwomen catch northern pike, largemouth and smallmouth bass, crappie, bluegill, channel catfish and bullhead in the lake. It’s open for boating, and a small campground is placed on its shore, just off Waterford Road. This winter, the lake is covered in ice and snow and is a resting place for large flocks of Canada geese.
When conditions are normal, the amount of water flowing into the dam is the same amount flowing out. But when the inflow exceeds the amount of water the outflow structure will allow, water backs up into the lake to prevent flooding downstream. The dam has an outlet tunnel that is 3 1/2 feet wide and nearly 7 feet high; it carries water from the outlet through the dam, and into the “stilling basin.” Water then flows through a channel to the end of the government-owned 44 1/2-square-mile drainage area, then the stream banks return to normal levels.
The dam’s flood control elevation is 1,146 feet, which means that when the water level reaches that point, it will flow through the spillway, which, according to Schray, is a relief valve to prevent the dam from overtopping.
“The spillway is a safety valve ... when water flows through the spillway, the dam is automatically shifting from storing water to reduce flooding downstream to releasing storage that might threaten the integrity of the dam,” he said. “This release might contribute to flooding downstream, depending on conditions, but in doing so prevents a catastrophic dam failure which would result in much more damaging flooding levels.”
There’s more information about the recreation opportunities at the North Branch of Kokosing River dam at http://www.lrh.usace.army.mil.
The Knox County On High series continues on Monday, March 3 ,with an exploration of the Devil’s Backbone.
