Be ethical and let the buyers know it was partly flooded...
This seems to be panedemic with insurance companies - one has to wonder how they manage to stay in business...oh, wait, they get bailed out by the taxpayers and then give themselves performance bonuses
There is nothing fresh about the Hudson south of Yonkers. Salt is the least of your concern.
slightly off-topic...depending on the tide...either way it's always brackish. But, I can remember as a kid (grew up two blocks from the Hudson in Yonkers) watching lots of ice float up and down the river, cause the fresh water from all the streams/creeks and farther upriver floats on top of the salt water and freezes below 32.
(do I really want to post this?)