There are many different definitions of where the floodplain is, and this graphic illustrates the difference between a regulation definition, FEMA’s Special Flood Hazard Area, and a topographic definition of a floodplain based off a Digital Elevation Model (DEM). Floodplains by Design uses the topographic definition of a floodplain and is working to restore functions that the whole floodplain provides.

Floodplains are the areas of low-lying ground adjacent to rivers, formed mainly of nutrient-rich river sediments and subject to flooding after storms and heavy snowmelt.

Floodplains: Vital for People and Wildlife

Floodplains by Design is a public/private collaborative partnership integrating flood risk reduction with habitat protection and restoration. We believe in bringing together everyone with a stake in floodplain management decisions to develop comprehensive solutions for each river. Together we can improve the ability of local, state and federal agencies to achieve their diverse floodplain management and ecosystem recovery goals – while ensuring public dollars are well spent. Investing in Floodplains by Design will:

  • Reduce flood hazards
  • Restore salmon populations
  • Increase agricultural viability
  • Improve water quality
  • Enhance outdoor recreation

Moving Forward Together

Today local, state and federal agencies, tribes, and nonprofit groups are working to protect homes, farms and businesses at risk from catastrophic floods while also seeking to restore floodplain habitat for salmon recovery. This is all necessary and important work. Yet the systems for managing floodplains are disjointed, uncoordinated and inadequately resourced. The Floodplains by Design partnership is addressing barriers to and creating incentives for integrated floodplain management. The partnership is currently focused on Puget Sound’s 17 major rivers. In addition, the Department of Ecology has awarded grants to 14 projects across the state that take the Floodplains by Design approach of integrating flood risk reduction with habitat restoration. Our combined efforts over the next several years will position Puget Sound — and Washington State — as a national leader in integrated floodplain management. Together we can protect:

  • Our richest farmland
  • The Northwest’s signature salmon runs
  • Recreational opportunities
  • Commercial, residential and industrial development worth billions of dollars


Drawing of a Flood Control Project