Gasparilla island hurricane damage The FEMA 50% rule, as part of the National Flood Insurance Program, mandates that if a home incurs substantial damage — determined when. Boren would motor out to the island in his skiff, and he and his wife would collect shells and fossilized sharks' teeth. 1. Rep. The Sanibel Causeway partially collapsed during the storm, leaving no road access to the island or nearby Captiva, Florida.