As an important part of a coordinated effort to restore Thornton Creek, we are seeking your permission to survey for and control any infestations of invasive knotweed that may be on your property or properties.

Knotweed (polygonum spp.) is an invasive perennial weed that spreads aggressively and contributes to stream bank erosion, displaces native plants and provides little benefit for fish and wildlife. When knotweed is left uncontrolled, it has the potential to spread and create infestations along the entire creek. Winter floods and beaver activity can bring new infestations to your property, even if you have not seen it in the past. If you suspect that you have knotweed on your property, we ask that you do not cut or mow it. Unfortunately, mowing will only spread the plant and make it more difficult to control in the future

Forterra aims to search for and control knotweed from the highest upstream source of Thornton Creek at Ronald Bog to its outflow into Lake Washington, and along all of its tributaries. This will be a multi-year effort. Best management practices for knotweed control include the use of an herbicide formulated for use near streams. Herbicides are applied by licensed staff and/or conservation crews. We are available to answer any questions you may have about the process or techniques we use.

Please complete this waiver by the end of July so that we can efficiently coordinate our field work this summer. This waiver allows Forterra and our crew to survey and control knotweed on your property this summer. If you choose to give us permission for multiple years, this waiver will allow Forterra and our crew to continue controlling knotweed on your property in the future. This helps ensure that plants are being treated consistently in a safe and effective manner. Forterra is able to provide this assistance at no cost to landowners with funding from the King County Wastewater Treatment Division.

This form will only take a few minutes to fill out. We appreciate you taking the time to complete it!