Eurasian Watermilfoil

The results are in on the Eurasian milfoil treatment performed this summer and they are better than expected. Last July, the city implemented the initial phase of the milfoil removal plan. This was performed with the use of a systemic herbicide that affects milfoil plants but not other desired aquatic vegetation. The treatment was applied over a one-day period and within two weeks the milfoil started showing stress.

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The treatment of the 2011 milfoil in Lake Stevens is considered to be highly successful, delivering more than 95% control of the Eurasian milfoil. In a site survey it was found that the majority of the milfoil plant stands have crashed to the lake bottom and are not visible. In scattered areas within the large treatment zones, there remained some severely damaged stems vertical in the water column, but well below the surface. These plants are not expected to survive the winter. In a few locations there are some plants that still show some life in them.

The city is planning on the next treatment in an ongoing effort to completely rid the lake of milfoil plants.

AquaTechnex has created a site to provide information on the 2011 treatment and other links to related information.

For More Information

• 2010 Eurasian Watermilfoil Density Map
• Integrated Aquatic Vegetation Management Plan
• Press Release (March 2011)
• Project Information and Status
• Triclopyr Fact Sheet

Snohomish County Hydrology Site
Lake Health Report 2015-2016