Need ideas: Removing a huge tree in a drainage channel

I've been struggling with good ideas for this, and I'm hoping to get some good ideas from the massive group intellect here

I have a huge tree, about 3 ft in diameter, that was growing next to a drainage channel (water 20 ft wide and 4 ft deep) and uprooted and fell in - just the root mass is a big 12ft diameter wall!
I'm trying to figure out some way to remove it with reasonable safety and as much ease as possible. I'm leaning toward getting a boat out and chainsawing it into pieces, but if there are better ideas out there I would love to hear them!

Fire is an option.
It would be wise to chain the top of the tree to keep it from flowing downstream where it may cause damage. This would also apply if you use a chainsaw.

Is it submerged? Fully? partially? How deep is the water? Could you use hip waders? Wet suit?
A chainsaw in a boat sounds dangerous. Be sure to tie up to the tree/anchor yourself well.
Know anybody with a tractor/equipment that could pull it out? Is it your drainage channel or is anyone else responsible for maintaining it? (water/sewer board, county)

Is it blocking drainage? If not, maybe you could just leave it there.

It's not blocking drainage, and it's remote so it's not really bothering anyone.

I have a tractor, but this thing is too heavy to pull even on flat ground, much less up a small bank.

I may try the Craigslist miracle approach with a "free firewood" ad

My point is that if it's not creating any problems or bothering anyone, removing it is work that doesn't need to be performed. Natural forces will eventually return this tree to the earth, and in the interim it will function as habitat for countless life forms. Ragged and productive is preferable to tidy and sterile. Less work, more benefit--it's a win-win. As far as free firewood, consider that valuable biomass, representing decades (perhaps even centuries) of embodied solar energy and soil minerals, will be removed from the land. It would make some awesome hugelbeets.