Knotweed Control Program

About the Program
Since the spring of 2010, the Pierce Conservation District has been leading knotweed eradication efforts within both the Nisqually and South Prairie Creek Watersheds.

Knotweed can affect the health of an ecosystem by competing with and crowding out native vegetation, reducing nutrient inputs which can negatively affect aquatic food webs, contributing to erosion of lands, and destroying prime habitat for local fish and wildlife. Since knotweed's primary form of distribution is through root and stem fragmentation, the flowing waters of rivers, creeks and streams serve as prime candidates for its dispersal.
A creek with overgrown vegetation and a log laying across it
Believed to have arrived in Washington State around the 1930's, knotweed has become widely established along many of our local waterways and are causing detrimental effects on local riparian and wetland habitats.

Program Update: 2014

The district wrapped up another treatment season this summer as we continued our efforts to restore important salmon bearing waterways, led by the district’s new Habitat Improvement Coordinator, Luis Yañez. This year marked an important milestone for the district’s knotweed efforts as it was the 1st year of re-treatment on the focus areas in the Upper Nisqually watershed. Another great combination of the district technicians and Washington Department of Natural Resources (DNR) donated Conservation Corps crews tackled the enormous task of walking 24 river miles looking for re-growth after previous years’ efforts.

The South Prairie Creek watershed also received continued efforts at control and retreatment. This important salmon stream that feeds the Carbon River had 2 full-time crews working its waterway this summer. The district was also successful in bringing more homeowners on-board to our control efforts. Many thank yous to all the Wilkeson and South Prairie Creek watershed homeowners who allowed the district to treat knotweed on their property.

The district also expanded its list of partners and supporters by completing smaller treatment efforts. The district once again worked in the Town of Steilacoom to control the spread of knotweed on private parcels and along the Town’s hiking trails. Steilacoom’s own Nancy Henderson led the effort of educating the public and spending a day showing the district staff the knotweed infestation sites.

The city of Puyallup and Pierce County Parks and Recreation also teamed up with the district to complete surveys of knotweed along the Puyallup River Walk Trail, Bresemann Forest in Spanaway, and Chambers Creek Canyon. The district will work with these two entities to develop management plans to control this invasive species along these popular recreation areas.
New Coordinator
  • Bill Simper, Habitat Improvement Coordinator
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