Special Projects

In addition to the monitoring and control of over 5,000 noxious weed infested sites in Thurston County, special projects are also performed  by the Noxious Weed Control Agency.

Brazilian Elodea (Egeria densa) removal on the Chehalis River

Brazilian Elodea is a non-native submersed freshwater aquatic plant. It was found in 1998 in the Chehalis River while surveying for purple loosestrife and parrotfeather. It was most likely introduced into the river by someone dumping the contents of their home aquarium into Plummer Lake, in Centralia. The plant then spread 54 river miles downstream from the point of introduction. Over the past 10 years 318,446 pounds of elodea bio mass has been removed from the Chehalis River. 

The Noxious Weed Control program began removing individual plants as early as 1999. Hand removal continued to 2003Crane on bridge removing weeds when the infestations became so large that individual hand removal was no longer practical. As of 2012 hand removal techniques have resumed due to the reduced plant number. In 2005 the infestation covered 35 acres, in 2014 less than one acre was infested.

A diver dredging pilot project funded by Department of Natural Resources was conducted in 2004. The project was expanded in 2005 with funding from U.S. Fish and Wildlife.  In 2006 the Chehalis Tribe joined the project, and began removal of elodea in the Chehalis River near Centralia. In 2007 the Department of Ecology provided funding to the Chehalis Tribe and Thurston County for increased removal efforts. In 2008, the Salmon Recovery Funding Board provided fundind through a project with the Nature Conservancy. From 2009 to 2016 the project continued with the U.S Fish and Wildlife Service and Washington State Department of Ecology again funding this project.

Removal will increase water movement resulting in higher dissolved oxygen. In 2007, oxygen levels were measured before and after removal efforts.  Following removal, oxygen levels increased 7.75%. Populations of elodea have now been reduced to the point where future readings will most likely not show any difference. Removal will also decrease sediment retention.

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Eurasian watermilfoil (Myriophyllum spicatum) removal on Black LakeDiver with Milfoil

Eurasian watermilfoil was first identified in Black lake in 2004. Similarities with other native plants made it necessary for scientists to perform DNA analysis to confirm the species as the invasive Eurasian water milfoil and not the native plant Northern milfoil. In November 2005, Eurasian watermilfoil was confirmed as the species collected at Black lake in 2004.

A project funded by the Washington State Department of Ecology  includes a thorough survey of the lake as well as manual diver removal of plants found. If the grant project is successful we may be able to prevent milfoil from establishing and taking over the recreational uses as well as the wildlife habitat of Black Lake.

Eurasian watermilfoil (Myriophyllum spicatum) removal on Deep Lake

Since 2007 efforts to control Eurasian watermilfoil has been ongoing. Surveys are done each year to determine size and locations of infestations. In March of 2014 the Thurston County noxious weed dive team surveyed in areas that had been previously infested. Although Euarasion watermilfoil was not found in previously infested areas, plants were found in a location in the middle of the lake that was thought to be a non vegetation zone. In May of 2014, survey and removal resumed.In 2014 for the first time, no Eurasion watermilfoil was found in any swim areas.

Project maps to view click on the year below:

2010    2011    2012    2013    2014

Variable-leaf milfoil (Myriophyllum heterophyllum) removal on Clear Lake and Blue Lake

Variable-leaf milfoil is a Class A noxious weed found in only 4 locations statewide. Thurston County has two of the infestations the largest in Blue lake which flows into Clear Lake. Clear Lake also has variable-leaf milfoil but just scattered infestations compared to Blue Lake. Efforts to control variable-leaf milfoil began in 2009 with a cooperative agreement between Thurston county noxious weed control and Pierce county noxious weed control.

During 2014, the division dive team manually removed 11,365 lbs of Variable-leaf milfoil. The funding for this work was from the Washington State Department of Ecology aquatic plants and algae fund. A follow up removal project occurred 2015.

[Back to the top]Purple Loosestrife Weed

Purple loosestrife (Lythrum salicaria) monitoring on Capitol lake

Great progress has been achieved in control of this invasive aquatic emergent species. Purple loosestrife threatens 44 native species nationwide including several endangered and sensitive species. Multiple private ownerships of the Deschutes River watershed, as well as Washington Department of Enterprise Services have all worked towards eradication of this invasive species on Capitol lake.

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Biological Control EffortsBruchidius villosus

Since the early 1970s, biological controls have been used as a part of the weed program’s work plan. Following rigorous screening by the U. S. Department of Agriculture, colonies of species-specific insects have been released annually. Thurston County’s weed program has collected, distributed, purchased, and contributed to research, in order to obtain additional biological agents to assist in the control of widespread noxious weed species.

Biological Agent Distributions:

  • Biological distribution map - to view, please click here.
  • Biological control fact sheet - to view, please click here.
  • Biological control information - to view, please click here.

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Contact Us

Address questions or comments to: tcweeds@co.thurston.wa.us