Just how deep is the average well in that area?
I recall seeing an episode of "This Old House" where they drilled 700 feet to reach a sufficient volume of water to supply the new house that was being built. I find it hard to believe that surface flooding of the area could seep through 700 feet and contaminate a well.
Is the problem due to old regulations that were not strict enough? I have read on the web that one part of proper well digging involves injecting hydraulic cement into the sleeve surrounding the water carrying pipe to a certain depth and then capping the surrounding surface of the pipe sleeve to a certain diameter and height above the ground with cement.
If the homeowners had flood insurance, couldn't a contaminated shallow well be written off as a total loss and have the insurance pay for drilling a new deeper well? It seems reasonable and logical.
I would think in an area that is prone to flooding, there would be one way valves that do not allow backflow contaminating the well.
Good luck!
Bountyhunter