Roesiger Invasive Plant Control Project

Developing a Plan

In 2021, Snohomish County Surface Water Management and the Lake Roesiger Community and Boat Club partnered together to develop an Integrated Aquatic Vegetation Management Plan (IAVMP) for Lake Roesiger. The plan focuses on long-term control of key invasive plants and was developed with in-depth community engagement including all area residents. 

The plan was approved by 64% of all voters which included lake users that do not live near the lake. Approval was 70% among lake area residents and 74% among Lake Roesiger Community and Boat Club members. The Washington Department of Ecology approved the plan in February of 2022.

Read below to see the history of the plan development and all related draft documents, meetings, etc. 

newburstgold50_png Funding obtained to start 2023 implementation

In 2022, volunteers from the Roesiger community worked to identify and seek funding to implement the Lake Roesiger Integrated Aquatic Plant Management Plan. The committee's work led to securing potential funding sources that will allow for implementation of the plan to begin in 2023. 


Grants

The Washington Department of Ecology has an Aquatic Plant Management Grant that provides up to $75,000 for invasive aquatic plant management. The grant requires a $25,000 match from the applicant. Snohomish County completed and submitted the implementation grant application in November 2022. Grant award notifications will occur by spring 2023. 


Lake Roesiger Surface Water Management Charge  

On November 23, 2022 Snohomish County Council passed an ordinance to establish a service charge specifically for invasive aquatic plant managemet at Lake Roesiger. The proposed charge can be seen in Snohomish County Code (pending update). 

You can view the interactive map to see parcels affected by the charge and the associated rate. For questions view the FAQ document . To see the history of how the chage was established, view the public meeting recording  and presentation


Snohomish County Surface Water Management and the Lake Roesiger Community and Boat Club partnered together to develop an Integrated Aquatic Vegetation Management Plan (IAVMP) for Lake Roesiger. The plan focuses on long-term control of key invasive plants and was developed with in-depth community engagement. 


In fall 2021, the plan was approved by 64% of all voters which included lake users that do not live near the lake. Approval was 70% among lake area residents and 74% among Lake Roesiger Community and Boat Club members. The Washington Department of Ecology approved the plan in February of 2022.

Read below to see the history of the plan development and all related draft documents, meetings, etc. 

Overview of Roesiger IAVMP Plan Elements 

Overview of Roesiger Aquatic Plant Management Plan Elements

The Issue

Lake Roesiger is home to an abundance of native plants. These beneficial plants are vital to keeping lakes healthy. They provide important food and habitat for aquatic life including fish, turtles, frogs waterfowl and other aquatic life. They also are important for us as they help to clean the lake by filtering pollution and prevent shoreline erosion. 

Unfortunately, Lake Roesiger is also home to a few non-native, invasive plants. These plants can crowd out the beneficial native plants, harm lake ecology, and interfere with swimming, fishing and boating. So while it is important to keep native plants in the lake, it can be desirable to manage invasive plants to reduce their impacts. 

The lake has three invasive species of concern in the lake basin - Eurasian watermilfoil, fragrant waterlily and narrow-leaved arrowhead. There are also three invasive species found on the lake shoreline - yellow flag iris, purple loosestrife and Japanese knotweed. See our aquatic plants page to learn more about the different types of plants and how to identify them. 
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Fragrant Waterlily Patch and Flower

Fragrant waterlily

Introduced as an ornamental plant, it takes over shallow areas, limiting habitat and boating and speeds causes the lake to fill in faster.

Eurasian watermilfoil

Noxious weed, grows in hard to swim through mats and crowds out native plants. Can reduce oxygen in the water. Easily regrows from broken fragments.

Eurasian Watermilfoil Patch and Flower

Grass-Leaved Arrowhead

 Less researched, may displace natives plants and wildlife, can be a nuisance to swimmers. Found only in 5 lakes in the state, including Lake Roesiger.

Grass-leaved Arrowhead Patch and Flower

Yellow Flag Iris

Grows in dense clumps in shallow waters of lakes and streams. A piece of root can break off and grow a new plant. Resin from it can irritate the skin.  

Yellow Flag Iris Patch and Flower

Purple Loosestrife

Emerges from the water in dense stands, spreads rapidly. Crowds out plants that make for good nesting habitat. Could be mistaken for spiraea or fireweed 

Purple Loosestrife Patch and Flower

Past Efforts

Since 1998 Snohomish County controlled Eurasian watermilfoil in the lake through diver surveying and hand-pulling. These efforts were effective in keeping milfoil levels low with only small patches growing each year. Unfortunately, funding for this program was lost in 2017. The Community Club has raised funds to hire divers for some hand-pulling work in 2019 and 2021.


Over the years, some individuals have worked to control fragrant waterlilies in from of their properties. However, the problem has persisted and there was a growing desire to have a larger solution. In recent years, the Community Club has purchased tools for homeowners to do lily control on their property and obtained a larger permit for participating landowners to lay bottom barriers. While these efforts may provide relief in small areas, they are not addressing the large scale infestation.


The Integrated Aquatic Vegetation Management Plan

In 2020, the community approached the County for assistance in applying for a  Washington State Department of Ecology grant program to help fund invasive plant control. The program requires that an Integrated Aquatic Vegetation Management Plan first be developed before communities can obtain funds for control work. The County applied for and was awarded a grant beginning in July 2021. 


Plan Goal & Steps 

Roesiger Plan Timeline Of Actions

The project goal was to provide the community with a road map which will help native plants, ecosystem health, and lake recreation. The plan laid out all options with associated costs and benefits so the community could decide on the best path forward. 


Step 1

Map Invasive Species

In July 2021, County staff conducted a survey of the lake mapping all locations of identified invasive species as well as inventorying the native plant species. These maps were used to assist in the plan development and can be viewed online:

Step 2

Develop Draft Management Plan

Snohomish County contracted with Tetra Tech Inc. and ESA to develop the draft plan. Tetra Tech and ESA have extensive experience managing invasive aquatic plants including knowledge of the latest research in control technology. They also have experience working with local communities to facilitate development of  IAVMPs. 


Members of the Lake Roesiger Community and Boat Club were instrumental in developing the draft plan. The Club appointed a steering committee of 12 members with representation from each lake basin. The committee met twice to 1) provide input to Tetra Tech and ESA regarding the plan goals and 2) review the draft plan and develop recommendations for the full lake community. 


  • Steering Committee Meeting 1: August 9, 2021 - development of plan goals and control options. Watch the recorded meeting and view the presentation.
  • Steering Committee Meeting 2: Scheduled September 9, 2021 -  review draft management plan and develop recommendations. Watch the recorded meeting and view the presentation.
Step 3

Present Draft Plan to Community for Input

The plan was drafted and included four different scenarios for plant control. Tetra Tech  and ESA provided an online presentation to explain the plan and the potential management options. The entire lake community was invited via mail, email, and social media postings to view the presentation and the draft plan and provide feedback via an online survey. 

Finally, there was a lake-wide community on October 26th to review the plan feedback and discuss next steps.  Watch the recorded meeting.

Step 4

The community input was used to revise the plan and a final community vote approved the plan.