Anyone want to put out on the table how to fix this problem without draining the lake. My plan is to make a clay damn around the old spill way pipe to seclude it from the lake water. The second video is where we are going to put a temp horizontal spill way pipe for water to escape in emergency situation until will get the spill way pipe in. Then once this is done we will pull the old spill way pipe out, put new steel spill way pipe in, pack really well and then dig the temp damn out.
That should work providing the dirt dam doesn't give way once the drain area is drained.
They make interlocking "W" shaped pieces of steel that I've seen driven down into the ground to make a temp. seawall. That might work too, but I have no idea what the cost would be. They can be vibrated and pulled out of the soil when the job is done.