Most of the south shore of Long Island is considered a low level marsh land with the entire shore front area approximately one or two feet above sea level. When these areas were developed for commercial and residential purposes more than 70 years ago, most roads and buildings were built without the concern for erosion or flooding. Drainage pipes were built underground in the bays and canals along the shore line, which causes many of the stormwater runoff concerns we have today.
When the south shore experiences heavy rain, flooding is expected to occur. As the rainwater floods the bays and canals, salt water floods over the bulkheads and causes additional flooding damage on roads and properties. In addition to flooding above ground, the salt water is pushed back into the drainage pipes underground, causing a surge within the pipes and overflow. All of this surge of water, both rain and salt water, adds to the contamination of the Great South Bay.
FEMA has designated most of the area as an AE6 Flood Zone, which means that anything less than six feet above sea level is prone to flooding. To find out if you live in a flood zone in Suffolk County, check out the online map at Suffolk County Flood Maps.