Citing heavy rainfall that overwhelmed the lower portion of Perrinville Creek, causing floods in December and January that washed out Talbot Road, damaged private property and threatened critical infrastructure, Edmonds Mayor Mike Nelson on Tuesday called for “immediate creation” of a plan to restore Perrinville Creek.
According to the city, during those storms in late 2020 and early 2021, the lower portion of Perrinville Creek received a massive amount of water and huge volumes of sediment containing silts, sands, gravels and rocks (up to 18 inches in diameter). As a result, the culvert under Talbot Road was overwhelmed and Perrinville Creek flowed over the road.
The city said that crews worked for several day and nights to try to keep the channel open and flowing, including hand-digging channels to keep the creek moving.
A detailed staff report of the incidents can be found here.
“Today I am calling for the immediate creation of a Perrinville Creek Restoration project plan,” Nelson said. “It is clear the current structure, built in the 1990s, is not able to handle the flow of water from storms and protect the wildlife that inhabit the creek. While emergency modifications are addressing safety and avoiding property damage in the short-term, a longer-term solution would provide both greater protection to nearby properties and a sustainable solution for the creek to function in its natural role as a habitat for salmon and other fish,” the mayor added.
Perrinville Creek has been impacted by excessive amounts of sediment that should be better controlled upstream, years of modifications on private property that, over time, have altered the natural course of the creek, and a culvert under Talbot Road that is a significant barrier to fish passage, the city said. Climate change is also altering the historic patterns of winter rainstorms, with a greater percentage of annual rainfall coming during the winter months and in fewer, but more intense, storms.
“There needs to be both a short-term resolution to maintain flow and prevent further loss of fish life, and a larger, longer-term solution to actually restore a sustainable fish habitat and population to this entire section of Perrinville Creek,” added Public Works and Utilities Director Phil Williams.
The ultimate resolution will require multi-jurisdictional participation between the City of Edmonds, City of Lynnwood, and Snohomish County, and will involve multiple private property owners, the city said. While working toward a short-term fix, city staff believe it is critical to also immediately begin developing proposals to move forward with a major restoration project in the near future.
The city is in the process of scheduling a site meeting with Washington Department of Fish and Wildlife staff as an initial step toward viable short-term solutions. For the longer term, staff as a first step are seeking a scope of work for a sediment source identification study. According to the city, this study will provide key information in developing initial concepts and bringing project partners to the table.
The city said this approach differs from its previous efforts in the basin, which have focused purely on reducing flow rates in the creek in order to reduce sediment loads. That previous work wasn’t sufficient to overcome the decades’ worth of historic damage to the creek and keep up with climate change.
Once staff have formulated a better idea of the full effort and cost required to pursue a restoration project, they will present it to Edmonds City Council for their review and direction, which will also include an opportunity for public input.