Why don't you have someone come in with a trackhole and dig it out deeper. That will cost less and get ride of all the cattailes and there roots. Just an idea
I've faced this a couple of times, and I fully agree with URUP's suggestion.
I made the mistake at our last home of filling in a pond a little bigger than yours. After draining it, and kind of filling it in, it took more than a year to finish cleaning it up. I only wish I'd have taken pictures of my tractor belly deep in the former pond, about six months after we drained and filled it with dirt.
We eventually sold the property to people we knew. If it wasn't for them, the filled in pond was a real distraction because it took several years to stabilize.
Cleaning it out should be an asset. Because of it's size, you can probably get somebody in there with an excavator, rather than a full sized track hoe. In any case, you are probably talking about a days worth of work for somebody with a track hoe or excavator and a dump truck.
. . . just a thought.
Good luck,
Ken
