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King County is reporting early success from a $19 million floodplain restoration project that’s helping young salmon thrive in the Snoqualmie River.
In April 2024, the county completed its largest-ever floodplain restoration project along the Snoqualmie River. The county removed more than half a mile of levees and other barriers to reconnect the river to its floodplain near Fall City.
The Snoqualmie River is confined by levees and revetments that limit the natural processes of the habitat. The project aimed to reverse the impacts of these hindrances.
A year later, the county says the project has improved salmon habitat and strengthened flood protections for nearby farms, roads and homes.
King County Water and Land Resources Division ecologists studied the 145 acres of restored floodplains and found the habitats are supporting strong growth in young salmon.
The study found that young Chinook salmon were gaining more than one-third of their body weight – and some gaining more than half their body weight – over the six-week study period.
Faster growth improves the chances of survival as salmon migrate to the Pacific Ocean and return to spawn.
"This study confirms the effectiveness of King County’s largest-ever floodplain project to restore the natural environment for people, fish, and wildlife," King County Executive Shannon Braddock said in a statement on Monday. “Through strong partnerships, our work along the Snoqualmie, Cedar, Green, and Duwamish rivers is simultaneously improving habitat and reducing flood risks, inspiring hope for a more resilient future.”
Funding for the $19 million project comes from the King County Parks Levy, including surface water management fees and grants dedicated to projects that reduce flood risks, boost salmon recovery and increase agricultural productivity.
Ecologists are already conducting a second year of research to examine a broader range of environmental and growth conditions.
King County says the project’s success could serve as a model for future restoration work in the region.