This area, and it's development, has always been a bit confusing to me. There are many places, along many rivers, that flood in the spring and are planted in early summer. The topography here though is quite different. The volume of water , and the make up of the soil ( which consists of glacial sill) is extremely unstable.The developers biggest problem is usually logistics, and this area has easy access, compared to more geologically stable areas. Where it went terribly wrong is when subdivision type development was allowed in such an unstable area. The buyer assumes there is an implied trust that the land and home they are buying is sound and stands on a good foundation. There is no requirement that developers apply logic to the location of the land they intend to develop. It is a " buyer beware " scenario and that is why flood insurance is very expensive, if one can get it.
    Before you agree to buy a property do a little research, ask your banker about the history of the area.