Thornton Creek Noxious Weed Knockout

Noxious weeds, like knotweed, are a non-native, introduced species that disrupt the Thornton Creek watershed’s entire ecosystem. Knotweed, a bamboo-like annual that can grow to 6’-10’ tall, has large heart-shaped leaves, spreads aggressively, and poses one of the greatest threats to the watershed’s ecosystem. Left uncontrolled, these weeds:

Reduce property value
Damage structures such as foundations and roads
Contribute to stream bank erosion
Lower nutrient inputs into stream systems
Crowd out native vegetation that provides vital food and shelter to native fish and wildlife

However, with your support, we can restore and improve the vitality of the Thornton Creek watershed by removing knotweed and other noxious weeds.

We are seeking your permission to access your property to survey for and treat any knotweed infestations with a low concentration of herbicide – which is the best tool we have available to treat this particular plant. Knotweed treatment typically takes several years to be successful, and allowing us permission to access your property for survey and treatment for several years will allow us to fully eradicate the weeds from your property. Your participation is part of a coordinated effort to restore Thornton Creek, and together, we’re reducing knotweed infestations and increasing habitat value along Thornton Creek.

Not sure if you have knotweed on your property? Reach out to EarthCorps and we can help!

To grant permission for this free service, please download and fill out the waiver. You can return via mail to EarthCorps, 6310 NE 74th Street, Suite 201E Seattle, WA 98115, or send a scanned (or photographed copy) via email to field@earthcorps.org

Details

How Much Does It Cost?

This service is free. We provide this assistance at no cost to landowners thanks to funding from King County Wastewater Treatment Division.

Who Is EarthCorps?

EarthCorps is a Seattle-based environmental nonprofit that envisions an equitable world where all people and nature thrive together. To actualize this vision, EarthCorps cultivates leaders and community partnerships to advance environmental justice. Since 1993, EarthCorps’ corps, volunteers, alums, and community have cared for the lands, waters, and people of the Puget Sound region and beyond.

What Are The Next Steps?

Once granted permission, an EarthCorps representative will contact you directly to schedule a site visit.

EarthCorps’ team will walk through the creek from one property to the next. We may need to walk across your yard. Please let us know if you would like to be home while we perform the control work or if you need to be there to let us through a gate to access the creek.

If we find knotweed during our site visit, we will schedule a secondary visit in which a licensed applicator will treat the noxious weed with a low concentration of herbicide. The herbicide is safe for people and animals within an hour of being applied.

When Will This Happen?

EarthCorps will be performing the survey and control work from mid-July through September. We will communicate with landowners prior to accessing their property.

Why are we targeting knotweed?

Knotweed was selected for this project for multiple reasons:

It is not yet as widely established as many of these other weeds, and so is more feasibly controlled;
It is extremely difficult to remove, requiring skilled application of approved herbicides or many years of painstaking labor;
It easily spreads by rhizomes and fragments that flow to downstream riparian areas, posing a serious danger to the watershed if it is not better controlled soon; and
It has extremely negative effects on riparian habitats, establishing a monoculture that reduces food sources for wildlife, lowers nutrient inputs into stream systems, creates bank erosion problems, clogs small waterways, and can damage structures such as foundations and roads.

Download Landowner Agreement Form here:

Knotweed Permission Form