I don't know if it would compromise the Bentonite layer (I ignorantly doubt it would), but you would have to add quite a bit of gravel to 6" - 12" of soft muck to firm it up. Last winter I ran the cows through a 16' strip they had never walked on before, which quickly created 4" - 6" of soft muck where turf had been. I had to add roughly 1/3 that thickness of gravel to the area to firm it up. I think under water (where it ain't gonna dry any) would probably be worse, and if there is any inflow of silt to the pond, could be an ongoing process.

It might be feasible for a limited area like a beach.

"Live like you'll die tomorrow, but manage your grass like you'll live forever."
-S. M. Stirling
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