The Corps of Engineers' Louisville office outlined the project in a public notice on March 2, giving anyone wanting to comment 30 days to do that before the project starts.
For visitors to Rough River, the emergency spillway modifications will be the most noticeable change.
The Corps plan calls for raising the height of the dam by five feet, which would raise the road across the 1,590-foot-wide dam by two feet.
The Corps said the other three feet would be a concrete barrier with a guardrail that will replace the existing guardrail on the upstream side of the road.
The current dam is 130 feet above the streambed.
Also part of the plan are changes to the outlet bucket at the base of the dam that the Corps says doesn't adequately dissipate energy when water's released.
To cut down on frequent repairs, the Corps plans to lengthen the concrete-paved apron, and baffle blocks may need to be put into the outlet basin.
These repairs will made within 90 feet of the end of the existing outlet, but the apron will go from 126 feet to 141 feet, 15 feet longer than it is today.
The Corps said work would have to be done to the rip-rap at the foot of the dam and along one side of the outlet pool.
Erosion of soil under the rip-rap, the report said, is causing the stone to sink.
Also, soil on the face of the downstream side of the dam is filtering into the rock under it, forming sinkholes.
Work also will focus on the seepage and artesian pressures that have caused damage at the base of the dam.
"The three relief wells have been generally ineffective in relieving those pressures," the notice said.
Additional relief wells or a downstream seepage berm may be built to "prevent excessive uplift pressures from developing and to handle the flow passing beneath the dam through the foundation soils," the notice said.
The Corps also is considering widening the spillway, requiring a new Hwy. 79 bridge over the spillway. The spillway floor may also be lowered and gates installed, gates designed to "fail" once overtopped with water.