Invasive Species

Invasive species are organisms including plants, animals, bacteria and fungi that are not native.  These species can be harmful to their new environments. In fact, invasive species are capable of causing extinctions of native plants and animals, reducing biodiversity, competing for resources with native organisms, and altering habitats. Invasive species can have enormous economic impacts and fundamentally alter ecosystems. 

Lake Ballinger Invasive Plants

Invasive aquatic species have been identified in Lake Ballinger. The City of Mountlake Terrace has a five-year Ecology permit (2019-2024) to use EPA- and Ecology-approved herbicides to control Eurasian watermilfoil, Fragrant water lily, and Curly leaf pondweed in Lake Ballinger.  Approximately 50% of the lake will be treated for Eurasian watermilfoil May 4, 2021 using a herbicide approved for use in potable water (brand name ProcellaCOR.)  There are no swimming or fishing restrictions required with the use of this herbicide, and all properties near the treatment area will be posted prior to the treatment to notify residents and park users.

Eurasian water milfoil

Eurasian watermilfoil

Eurasian Watermilfoil is not native to Washington State but has been imported for use as an ornamental plant. It forms dense mats that shade out other aquatic plants, degrades water quality, inhibits water flow and impacts recreation. Learn more here.

Citizens and staff from Mountlake Terrace and Edmonds are working together to control a severe milfoil infestation in Lake Ballinger. If you would like to be involved in this effort, please contact Laura Reed, Stormwater Program Manager, at 425-744-6226. For more information on how control milfoil, please see the WDFW publication "Rules for Aquatic Plant Removal and Control (PDF)."

Fragrant Water Lily

Fragrant Water Lily

Invasive Fragrant Water Lily vs. Native Yellow Pond Lily

On Lake Ballinger, Fragrant Water Lily has taken hold in many areas around the shore. Fragrant Water Lily is not native to Washington State but has been imported for use as an ornamental in backyard ponds and is now found in many of the shallow lakes in the area. It has overtaken native Yellow Pond Lily in many areas around the lake. Learn more here.

Native Yellow Pond Lily

Native yellow pond lily
  1. Why act now?
  2. Why are these plants a problem?
  3. What's the goal of the treatment?
  4. What has been done so far?

While the herbicide treatment applied in July 2019 was successful in eliminating much of the Eurasian watermilfoil in Lake Ballinger, some plants have remained and re-established, particularly on the east side of the lake, which was not treated.  

Volunteer Invasive Species Removal

See how the Girl Scout Troop 44253 got involved with fragrant water lily removal at Lake Ballinger!

Remember:  always check boats and fishing gear when you enter or leave the lake; remove all plant fragments and toss them in the trash.

Concerns or questions?  Please contact:  Laura Reed, City of Mountlake Terrace, Project Manager at or (425) 744-6226.