What is happening at Vancouver Lake?

Over the past several years a noxious weed known as Eurasian Milfoil has proliferated making it increasingly difficult to recreate and enjoy Vancouver Lake.  A local group of citizens organized as Friends of Vancouver Lake because of their concern about the growth of milfoil in the lake. They raised funds and hired a lake and aquatic plant management firm, AquaTechnex to treat the lake.

AquaTechnex will apply a reduced risk herbicide known as ProcellaCOR to the weed-infested areas of the lake in an attempt to treat the milfoil. This treatment will take place on or about July 7, 2020, depending on several factors, including weather conditions.

Clark County Public Works offers more information and details about the application event here.


How does this activity impact the flushing channel?

The flushing channel, which is owned by the Port of Vancouver, feeds  water from the Columbia River into Vancouver Lake. Because a small amount of milfoil has been found in some areas of the flushing channel, Friends of Vancouver Lake requested permission from the port to treat the flushing channel to help control milfoil that might enter the lake through the channel. The port has granted an access agreement to Friends of Vancouver Lake to allow the treatment.

AquaTechnex is putting signs up around the flushing channel on Monday, July 6, 2020, to inform the public, with treatment scheduled to occur on Tuesday, July 7, 2020.


What is causing the milfoil issues at Vancouver Lake?

The cause of the milfoil infestation is unknown. Eurasian Milfoil is a commonly occurring aquatic weed in many lakes and waterways like the Columbia River. 


Why is the treatment being done now?

Conditions such as plant growth and water levels can impact the success of the treatment. Early summer is the preferred time for application because the plants are actively growing and will absorb the herbicide in the most effective manner.


How were people notified of the ProcellaCOR treatment?

AquaTechnex mailed a postcard to business and residential property owners within one-quarter mile of the shoreline of the portions of Vancouver Lake to be treated, as required in the permit issued by the Washington State Department of Ecology. 


For more information on milfoil treatment at Vancouver Lake please visit or contact:


Friends of Vancouver Lake

Kathy Gillespie, 360-901-6538



Larry Cassidy, 360-798-1249



Terry McNabb



Clark County Public Works

Magan Reed, Communications Manager




Port of Vancouver USA (flushing channel questions)

Therese Lang, Director of Communications




State of Washington Department of Ecology

State of Washington Noxious Weed Control Board

Clark County Weed Control Board