The 100-year floodplain, also known as the Special Flood Hazard Area (SFHA), is an area of land that has been determined by the Federal Emergency Management Agency (FEMA) as having a 1% chance of flooding in any given year. The floodplain is composed of a flood way and a flood fringe. The flood way is typically determined to be the channel of a river or stream and the overbank areas adjacent to the channel. The flood fringe is the area to either side of the flood way that is subject to flooding but conveys little or no flow. In Winnetka, there are two sources of floodplain: the Skokie River and Lake Michigan.