Good morning,
OK, Pondman and Esshup, looks like we are the only ones home on this topic. I have read enough of both of your posts to respect your opinions. So a sincere thank you first for hanging in there and being patient with my questions. Either way I go with this is going to be a long and challenging process.
My pond was not compacted with the kind of equipment both of you describe. So IF I have to go the route of draining and rebuilding with heavy equipment I will have an opportunity to also compact the bottom properly.
Rainman, if I understand you correctly I will have to figure out how to raise the level of the pond several inches above full then add a fairly large amount of H. lime to the water for the lime to have a possibility of working. I�m thinking that this is so because the WC is a marginal plant that grows along the edge of the pond and the roots need to be completely covered with the H.lime & water to kill the roots that grow upward into the bank of the pond. I think this would be possible to do because of the way my drain pipe is constructed. I have the kind of drain pipe that drains off the bottom and connects to the standpipe with an inverted Y pipe close to the top of the vertical standpipe. The full water level of the pond is the crotch of the Y. So if I can get a pipe with an outside diameter very close to the size if the inside diameter of my standpipe I could make it long enough to slide inside the standpipe low enough to block the input from the bottom of the Y that drains the pond. That way the top of the standpipe would be the high water mark and that is a about an inch short of the level of the overflow spillway. That would raise full water mark to the point that part of the spillway is filled and the entire edge of the pond is covered.
Before doing that I think I might be wise to dig up a core of the WC and �plant� it in a jar and cover the roots with a H.lime solution and see if it kills the plant. I also think I should check with the local extension agent because with the pond that full of a toxic lime solution a rainstorm would surely cause a runoff. I wouldn�t want to cause damage downstream. I could do it with an eye on the forecast to plan doing it for a week without any rain in the forecast.
Either way I do this is going to be a long and involved project. If I can do it without heavy equipment it will cost a lot less and I think this approach will offer a greater chance of success on the first attempt.

Kru Heller
Powhatan, Va.