Resilient Floodplains for People & Salmon

Effective floodplain management can protect communities, recover endangered species, and uphold Tribal treaty rights.

August 20, 2024

Floodplains in the Pacific Northwest

Floodplains - low-lying areas adjacent to river channels or estuaries that can be inundated by flood water or subject to channel migration – provide invaluable ecosystem services including flood damage mitigation, improved water quality, economically valuable farmlands, recreational opportunities, and critical wildlife habitat for salmon and other species. Here in the Pacific Northwest, our floodplains are especially dynamic landscapes, shaped and reshaped annually by high flows every winter and spring.

Federally endangered salmon species rely on healthy, connected floodplains for crucial spawning and rearing habitat and as a source of clean, cold water during summer months.

A group of adult Chinook salmon swimming. — Chinook salmon photo courtesy of Washington Department of Fish and Wildlife.

Unfortunately, many floodplains in the Pacific Northwest no longer function in their natural form because they have been restructured to meet urban and agricultural needs. Development disconnects river channels from their floodplain and destroys natural riparian upland and wetland vegetation. There is a direct, pronounced relationship between this loss of floodplain function and declining salmon runs—and with them, a failure to uphold Tribal treaty rights.

“Floodplains and salmon are deeply connected,” said Melissa Speeg, salmon recovery manager at the Puget Sound Partnership. “Young salmon rely on them for shelter and food when rivers and streams swell from flooding and spring snowmelt. Healthy floodplains with trees and plants slow the flow of water during flooding, providing a place for salmon to shelter and benefits to people that live downstream. Because floodplains slow water down, nutrients accumulate making the soil rich, which is why agriculture lands are located along rivers. For this reason, the cycle of flooding and floodplains is just as important to people as it is to salmon and re-establishing them is key for our future.”

Reversing that trend—and doing so in a timeframe that will prevent salmon from going extinct—will require bold, innovative policy solutions at all levels of government.

Restoration activity seen along the bank of the Skokomish River.

A view of the wetland at the Nisqually Wildlife Refuge.

Construction vehicles gathered along a gravel road in preparation for construction on the Dungeness River levee.

Salmon recovery projects are affected across Washington state

Click on project locations to explore FEMA no-rise policy impacts.

FEMA_Impacted_Projects_06.11.24

Learn more about the effect of project delays from the project sponsors

Photograph of salmon within the Skokomish River Mile 5 project area.

Photograph of eroding riverbank at the site of the Satsop River Mile 2.5 project.

Photograph of the eroding riverbank of the Nooksack Tribe's South Fork Nooksack Homesteader project.

A floodplain covered in water. Channels of water and plants are viewable in the foreground and Mount Rainier is seen in the background.

Would you like to contribute to this StoryMap?

Contact April Gassman at april.gassman@psp.wa.gov to add your project to this StoryMap.