Floating Primrose-Willow Control at Chambers Lake

Floating primrose-willow is limited in distribution throughout Thurston County. It is currently only documented in Chambers Lake in Lacey. 

We have performed control the past two seasons and are seeing success with the treatment of this Class A Noxious Weed. 

We will continue to survey and perform control on plants until eradication is achieved.

Variable-leaf Milfoil in Blue Lake

Variable-leaf milfoil is a Class A noxious weed and extremely limited in distribution in the state.

Thurston County has infestations on two lakes; Blue Lake and Clear Lake. 

Control efforts have varied over the years, using a combination of herbicidal treatments and manual removal by snorkelers. 

Continued monitoring and control are possible through Washington State Department of Ecology Aquatic Invasive Species funding.

Deschutes and Chehalis River Knotweed Control

Knotweed is a group of noxious weeds, widely distributed around Thurston County.  

Our crew performs surveys and chemical control along stretches of the Deschutes River (with landowner permission). 

We survey and treat roughly 30 river miles each season. 

The Chehalis River knotweed infestations have been surveyed and underwent their first year of treatment by a contractor in 2024. 

We continue to monitor and treat infestations within these two waterways.

Chehalis River Parrotfeather Control

Parrotfeather is a Class B noxious weed, designated for control in Thurston County. 

Surveys and treatments are completed annually by staff. The stretch of river covered by staff averages to about 9 river miles.

Black River Purple Loosestrife Control

Annually, our crew surveys roughly 8 miles of river and spot treats purple loosestrife plants as they are found. Currently, purple loosestrife is the only documented noxious weed along the Black River that is mandated for control. We continue the treatment and survey of this waterway in hopes of eradicating purple loosestrife and catching any invading noxious weeds before they become established.

Lake Lawrence Yellow Flag Iris Control

Yellow flag iris is required for control at Lake Lawrence, Deep Lake, transportation ROWs, and Thurston County properties. Annually, a contractor is hired to control yellow flag iris at Lake Lawrence with permission from the respective property owners. We are continuing to utilize contractors to manage this project. Thurston County rights-of-ways are treated by Noxious Weeds staff annually.

Private Property Knotweed Treatments

In addition to the Deschutes and Chehalis work, we are continuing to treat knotweed for private property owners throughout the county. This began with 14 sites in 2019 and has increased to 58 sites in 2024. Since the upland treatments began, we have assisted over 150 property owners with knotweed control. We will continue to add sites each year as older sites are eradicated.