Big project.
Welcome to the forum.
The lillies can somewhat selectively be controled with a herbicide. I say somewhat selectively because the rhizomes of one plant may be connected to the one next to it. So a systemic herbicide could kill several down the chain if you are only trying to selectively kill off part of the lillies. If you want to kill them all not a problem.
Any herbicide control of weeds be careful to not do all the pond at once. Too much dead matter decaying all at once can cause a low DO event and fish kill. Kill off sections at a time over a period of time.
Coontail I know what is because it grows wild in local streams but I am unfamiliar with its control.
Muskrats can be trapped.
15 ft sounds like enough depth to me but I am much further south. Down here we usually do not dig ponds deeper than 10 feet. But your location may need to be deeper to prevent winter kill.
Your options sound thought out. None are likely cheap, but what is today? At least you have a nice size BOW to work with.
Last edited by snrub; 12/10/17 11:08 AM.
