I know of no other way than to get a knife or a pair of sharp scissors or pruners, and start cutting it out in pieces.

Beer will help. And a college kid or two. Works in Canada anyway.

When my water lilies took over my pond I had to cut them up in pieces to get them out. Since I have a liner in my pond another forum member (nosambos) suggested I use a hacksaw blade to cut through them. This prevented me from accidentally cutting through my liner and worked like a charm. Although it took a long time.

Jenny

Drain the pond of water that can saturate the plants, leave the plant mass to drain as far as is practical.

Salvage pieces of plants that you like, snipping well rooted and shooted young hardy rhisomes for re planting

When the plant mass is really dried it will weigh considerably less and yank out in large manageable chunks.

Getting a rope round large sturdy clumps like iris and towing them out with a riding mower, or vehicle would save some lifting, using planks as a ramp to drag the mass up and out of the pond

I'd estimate the lifting weight of dried pond plants can be a lot less than 20% of a wet mass, assuming there is a large volume of dirt and sediment accumulated that the plants have grown among

Thanks for the suggestions. We drained the pond, put the fish in a tub and got in the pond and cut out the "island" with a sharp knife, pruning saw, and hatchet. It took four days, but the pond is without the island!!!!!
My husband said it probably weighed a ton.

Hee, you should have used the beer on the college kids.