Many of the affected homeowners do not even have federal flood insurance.

In Krotz Springs, just 51 of 560 homes there have that coverage, according to a review by the New Orleans Times-Picayune. In nearby Butte LaRose, 80 percent of the homes lack that insurance.

Some owners cite the expense, and others just don't expect to get flooded — either because they've raised their homes or have never seen flooding there.