Flood-prone areas are those areas that would likely be covered with or carry water as a result of a 100 year flood event, or that would have a 1% or greater chance of being covered with or of carrying water in any given year based on current circumstances or maximum development permitted under existing zoning (25.09.020 B). These areas have been substantially identified through the Seattle Floodplain Development Ordinance, Federal Emergency Management Agency (FEMA) maps, and mapping activities undertaken by Seattle Public Utilities; however, additional areas meeting the designation criteria may exist and are subject to ECA regulation.
Flood-prone areas identified on FEMA maps are regulated through the Floodplain Development ordinance (Seattle Municipal Code 25.06), as well as the ECA code.
Development in flood-prone areas may be required to be elevated or use flood-proof structures, and structures may be required to be located outside of floodways.
- Seattle Municipal Code 25.06: Floodplain Development
- Seattle Municipal Code 25.09 Regulations for Environmentally Critical Areas
- CAM 103B, Environmentally Critical Area Site Plan Requirements
- CAM 327A, Environmentally Critical Areas Exemptions, Relief from Prohibition on Steep Slope Development, and Modifications to Submittal Requirements — Application Instructions and Submittal Requirements
- CAM 327B, Environmentally Critical Areas — Small Project Waivers Application Instructions and Submittal Requirements
- CAM 328, ECA Exceptions
Related Director's Rules
- DR 8-89, Development Activity Requiring a Permit or License Under the Floodplain Development Ordinance: Exemptions