Not that I don't believe you, but for your own good, how are you sure there are no fish?
With water that deep, I would go with a strong aerator with multiple diffuser heads. This should not heat the water significantly but would be slightly difficult to place. Put them on the bottom but not the deepest part to leave a cold bottom. Downside is pulling up the diffuser would be difficult.
Alternatively go with surface aeration. Will be less effective but better than nothing. Plus side is it's on the surface not 60 feet down.
Don't worry about heating the water, 2 acres and almost 100 feet deep, that's a lot of water.
