The Olympic Invasive Working Group (OIWG) has been battling knotweed since 2005. Funding for most of this work has come from the Washington State Department of Agriculture. This funding will not be continued indefinitely, so Clallam County Noxious Weed Control Program has begun a policy of involving landowners in the eradication of knotweed on their own property.
Report a knotweed infestation here, but note that we are mainly concerned about knotweed near rivers, streams or lakes or on roadsides or in pits.