SNADs are mapped "only in areas where outstanding natural features or areas of natural beauty are to be protected. The preservation of such areas is important because they contain areas of special ecological significance, interesting geological formulations and rock outcrops, unique aquatic features such as tidal wetlands, unique topographic features such as palisades, valleys and hills, important plant life such as glaciated oak-chestnut forests or because they serve as habitats for native flora and fauna." (Section 7412-10 of the zoning text)
The NYC Planning Commission adopted Special Natural Area District (SNAD) zoning regulations in 1974. The Commission updated and strengthened the regulations in 2005.