Since it is only a half acre could you not just drag it out with a rake over time and mulch it.

I dont know what you have but one year I had a problem with water primrose. It was mostly covering the edges out to 15' or so, more in some places. I pretty much could go around the edge of the pond where it started and pull in the parts going out deep.

Maybe you could do the same thing. Or use a boat and a rake. And then if it seems like it is going to come back quickly then treat it with a biological solution (certain fish) or treat it with chemicals.

If you can get the bulk out before you treat it with chemicals it may prevent water quality problems when it dies and begins to decay.

Bill

I wish I had the tenacity of GSF!