Floodplain Development Regulations Update - What & Why
What’s Happening Now?
SDCI completed proposed permanent Floodplain Development Regulations and published the Threshold Determination on August 1, 2024 in our Land Use and Information Bulletin under Other Land Use Notices. The intent of this declaration is to satisfy the requirement of the State Environmental Policy Act (SEPA; RCW 43.21C), including the requirement to inform the public of agency decisions pursuant to SEPA. The SEPA documents including the attachments for the proposed permanent Floodplain Development Regulations and Director’s Report are on the Project Documents page.
This SEPA decision analyzes the full range of regulatory changes that were part of the interim Floodplain Development Regulations adopted on July 19, 2020, as Ordinance 126113 and the additional regulatory changes proposed for the permanent Floodplain Development Regulations. The additional changes include SDCI’s proposal to increase the elevation for construction from 2-feet to 3-feet above base flood elevation to account for sea level rise and new sections that include standards for the storage of materials and equipment, and standards for accessory structures.
Project Benefits
Our floodplain development regulations protect people, property, and the environment by regulating the development that occurs in the mapped floodplain and flood prone areas. The new permanent regulations will adopt FEMA’s 2020 new Flood Insurance Rate Maps and Flood Insurance Study and will continue to regulate flood prone areas mapped by Seattle Public Utilities. Below are examples of development regulations and these regulations vary depending on the specific flood zone designations, characteristics of the property, and the nature of the development.
- The elevation that the first floor of a new structure must be built at to keep the first story above anticipated flood levels
- Structures must be engineered to withstand wind from anticipated storms
- Structures must be engineered to withstand flood waters should anticipated flood levels be exceeded
The End Result
The permanent Floodplain Development Regulations will meet FEMA's 2020 requirements.