Aquatic Plants 

Essential for healthy lakes

Aquatic plants are natural part of healthy lake systems. They are the base of the food chain and provide key benefits to people and wildlife including:
  • Better fishing –  The  best fishing spots are typically near plant beds for a reason - fish eat the insect larvae, snails, and other critters in the plants. Plant beds are also nurseries providing ares to spawn and cover from predators.
  • Beneficial habitat – Fish aren't the only critters needing aquatic plants - turtles, frogs, ducks, and songbirds, are just a few of the animals that rely on aquatic plants for food or homes. 
  • Erosion Control - Aquatic plants protect shorelines from waves and erosion. They also help keep sediment on the lake bottom keeping the water clearer.
  • Cleaner Water – Aquatic plants can soak up pollutants from contaminated water. They also out-compete algae for limited nutrients reducing potentially harmful algae blooms. 

Invasive Aquatic Plants - A threat to lakes

While native plants are important parts of lakes, you may have heard about problematic plants, such as Eurasian watermilfoil. These plants are considered invasive, meaning they are not native to this area that do not have natural controls. They can be harmful to lakes by:

  • Spreading aggressively forming dense mats of vegetation
  • Crowding out and replacing beneficial native plants
  • Harming fish and other aquatic life
  • Impeding swimming, boating, or other recreation

Once lakes become infested with invasive plants, it is extremely costly to control them and nearly impossible to eradicate them. The best strategy is to prevent them -you can help by making sure you Clean, drain, and dry your boat when you enter or leave a lake making sure you remove all plant fragments.

Common invasive species to watch out for in our area include Eurasian watermilfoil, fragrant water lily, slender arrohowed, purple loosestrife, and yellow flag iris. See our ID sheet for common native and invasive plants. 

Options for Aquatic Plant Removal

Some landowners think they are helping to clean out the lake by removing aquatic plants in the water and along the shoreline. While intentions may be good, removing plants is not helpful to the lake health. However, if you are dealing with an infestation on an invasive plant species or if densely growing native plants are preventing you from swimming or boat, there are some options. 

Step 1: Identify your plant 

To make a good plan, you will need to know the plant you are working with to figure out the best removal strategy and the restrictions on removal. You can use the online plant identification resources or you send a photo of the plant to [email protected]. Once you know the plant type, we can help you identify the best strategy. 

Step 2: Read the Rules 

Plant removal affects the whole lake and not just your property. The Washington Department of Fish and Wildlife (WDFW) has established rules to try and balance the needs of homeowners and the lake health. WDFW's aquatic plant and fish booklet lays out the rules and serves as your permit for activities like hand removal and bottom barriers. There are additional herbicide restrictions (see info below). 

Step 3: Decide on Area to Remove Plants

The amount of area you can control depends upon your type of plant as found in WDFW's booklet.  
  • Native plants - you may only control a 10 foot corridor of native plants to provide swimming and fishing access. This means ten-feet wide section of your shoreline out into open water and NOT 10 feet along your entire shoreline. 
  • Noxious weeds - there is no limitation to the amount you can remove for noxious weeds like fragrant water lily or yellow-flag iris. Check WDFW's booklet for restrictions on the timing of removal that is set for some lakes to avoid affecting fish spawning. f you think you have Eurasian watermilfoil, please do not try to remove yourself as it spreads by fragments and may make the problem worse.  and instead contact us for options.

Step 4: Choose your Control Method

Hand Removal - Hand removal is the best option for removing small areas of plants. People use items like weed rakes or weed “razors” that you throw out into the water and cut the plants. Once you cut the plants, remove them from the lake or they will decay and cause algae blooms. Some landowners have even hired 

Bottom Barriers -  Barriers are burlap, landscape fabric or similar product that is placed on the lake bottom to prevent the emergence of aquatic plants. Barriers are only appropriate for small areas as it smothers the lake bottom killing all aquatic life. Refer to WDFW's booklet for restrictions such as the size of barriers and the amount of time they can be kept in place. 

Mechanical Removal - For large-scale infestations of noxious weeds such as fragrant water lily, it may be an option to use weed mowers or harvesters. Some groups have purchased a mower for their lake and others have hired commercial operators. Mowing large areas may require a permits from WDFW and can be challenging on lakes that do not allow motorized watercraft.

Herbicide Treatments -
 There are herbicides specifically formulated for aquatic use. However, all products that can be used in lakes are classified as "restricted use" in the State of Washington because of the potential impact to aquatic life and drinking water. All applications require a permit and must be applied by a licensed applicator. The Department of Ecology is the entity responsible for issuing permits in the State of Washington. Obtaining an herbicide permit involves ensuring everyone in the area is aware of the application and has an opportunity to provide feedback. Therefore, this approach is typically only used when there is a large problem and a community is joining together to collectively find a solution