Planning with Nature: Adaptive Management for the Lyon Creek Flood Mitigation Project

Lyon Creek just after it opened in November 2015
Photo by Jerry Pickard

On December 5th, former LFP Mayor Mary Jane Goss cut the ribbon for the Lyon Creek Flood Mitigation Project before a group of residents, business owners, and current and former politicians.

Construction of the $6.8 million grant-funded project lasted six months and included a number of fish passage and habitat improvements as well as flood reduction measures.

Though the ribbon cutting signaled the ceremonial end of the project, changes to this reach of the Lyon Creek stream corridor are not complete. The City will continue to monitor the plantings and the stream channel for three years using adaptive management concepts to ensure the creek has a stable and shaded low-flow channel with capacity for large flood events.

The City will continue to work with Watershed Company and representatives at the Washington Department of Fish and Wildlife to improve this reach of Lyon Creek.

While the City engineered and constructed a meandering stream channel as part of the Lyon Creek Flood Mitigation Project, Lyon Creek has begun to find its own path in some areas of the project.

Rather than attempting to force the stream to conform, the City has embraced the concept of adaptive management – planning with nature, rather than planning for it. This is the first year the creek has been in its new channel and it has not yet settled into its long-term stream channel alignment in some areas.

As Lyon Creek meandered it washed away some of the initial plantings that were intended to shade the creek and stabilize soils. Meanwhile, new sediment deposition areas have begun to reveal themselves. These sediment deposition areas will be stabilized and planted with a variety of native trees, shrubs and plants in spring/summer 2016.

The City will also replace plants that have died or been washed away. Please be patient with the plantings along the creek as they may take three years to become established and shade the stream channel.