PA Department of Environmental ProtectionA floodway is the portion of the available flow cross section (channel of a stream or any other watercourse and adjacent floodplain area) that cannot be obstructed without causing an increase of more than a foot in water-surface elevations. The Federal Emergency Management Agency has established the amount to be one foot based on floods that occur, on average, every 100 years. Floodways generally depict those areas where flooding is deeper and more severe. The designations are made in an effort to control the increase in flood heights.ArcGIS DynamicMapLayerhttps://hub.arcgis.com/datasets/349c986159b342f298b83b1023de92a2_223engPennsylvania Department of Environmental ProtectionPublicWater Obstructions and Encroachments - Floodway Activity Locations [Pennsylvania]Web servicesPennsylvaniaLast Modified: 2026-03-09