I have a planting area that gets semi-flooded in winter and I need a tree that will tolerate that. I can't modify conditions so a tolerant species is my only hope.

Thanks for any suggestions.

That's a toughie. We had a weeping willow that survived and did well in a very wet place. They can be beauties if you have the space for them, and they grow very fast into a huge tree.

A couple of (many) suggestions;
As the name suggests, Betula nigra (River Birch)
Liquidamber styraciflua (Sweetgum)