Smith Creek Tidal Restoration Naselle, Washington

Willapa Bay is a significant ecological resource with a community dedicated to its restoration and conservation. Through physical investigation, modeling, alternative analysis, and design, tidal inundation to 100 acres of estuary habitat would be restored as well as fish passage to Smith Creek, a tributary to Naselle River and Willapa Bay.

Restoring a Estuary Habitat and Designing a Bridge for Climate Change Resilience

Development and levees on the Naselle River floodplain had kept juvenile salmonids from prime rearing habitat and reduced the tidal flux into Smith Creek. In addition, the crossing at the mouth of Smith Creek is formed by an embankment with two 72-inch culverts with collapsed and failing tide gates. In restoring the natural connection, the gates would be replaced with a 100-foot-span bridge to achieve unconstrained tidal flux, fish passage, and scour designs. A cross levee protects nearby private land and roads. To inform a resilient design, high-magnitude flood models were used to assess conditions resulting from climate change and mapped historical channels in the floodplain to improve salmonid habitat.