Finding a balanced approach for aquatic plant management

Yellow flag iris in a green field near the interstate.

Yellow flag iris has made this drainage ditch unusable.

We are now accepting comments on our environmental review of chemicals used to manage aquatic plants and algae covered by two of our general water quality permits. These chemicals are used to manage noxious weeds, nuisance plants, and algae in and around water.

Our draft environmental study reviews eight new chemicals, five alternatives for management, and updates information on other chemicals currently covered under the permits. We're seeking your feedback now through June 6.

Click here to review the environmental study and submit your comments.

Environmental management:the balancing act

Sometimes, protecting the environment requires us to choose between two imperfect options. Just as you might turn to cold medicine to treat your body when you’re sick, we permit the use of some chemicals to help maintain the health of our waterways.

Noxious weeds are non-native plants that are highly destructive, competitive, or difficult to control. Nuisance plants are native, but they are growing in an area — or density — that causes damage the surrounding environment. These plants choke irrigation ditches, cover our lakes in green slime, and can be a risk to public health. While we work hard to keep chemicals out of Washington waters, we allow them under very specific circumstances to help manage these plants and algae.

Caring for the environment is a delicate balancing act. Our permits require people to use management solutions that have the least environmental impact among reasonably available options. Over the years, we’ve found chemicals sometimes can be the least invasive solution to control the plants and algae that throw off our natural balance.

Evaluating the chemicals covered by our water quality permits

We issue permits that allow the use of chemicals to conditionally treat noxious weeds, native nuisance plants, and algae in and around water. Two of these permits cover the use of chemicals in Washington waters. These are the Aquatic Plant and Algae Management and Aquatic Noxious Weed Control general permits. Our scientific review allows us to determine if we should — or should not — allow specific chemicals under our permits.

For these permits, we’ve evaluated:

Algae under a microscope.

Algae under a microscope.

  • Algaecides - A chemical compound that kills or reduces the growth of algae or cyanobacteria (known as toxic algae or blue-green algae).
  • Herbicides - A chemical compound that kills or inhibits the growth of plants.
  • Phosphorus inactivation products - Products used to bind phosphorus in the water column and sediments making it unavailable to aquatic life. Phosphorus is a key ingredient in algae blooms.

These chemicals are only effective at targeted plants and algae. Our permits ensure the chemicals used, and the methods by which they’re applied, are the least impactful to animals and other plants. Permits limit which chemicals are allowed to be used, where they can be used, and who may use them. They also require public notification before a water body is treated, and outline specific rules around the reporting and timing of applying the chemical.

Learn more about invasive plants and the risks they cause to our way of life from the Washington Noxious Weed Control Board.

Why not just remove them by hand?

Non-chemical options are not always the best solution with the least environmental impact. Physical and mechanical methods of removing these plants can be damaging to aquatic habitats. These non-chemical options can have negative effects on water quality, disrupt sediment, and can kill the insects, snails, and fish trapped in the plants. These methods may be so expensive that they’re not really attainable to water managers. In addition, they can lead to a new infestation of noxious weeds by leaving behind plant fragments that then take root in the sediment.

Allowing pesticides to manage Washington waters

The federal Clean Water Act gives Ecology the responsibility to protect state waters. Chemicals used to manage Washington waters must be approved for use by the U.S. Environmental Protection Agency and Washington State Department of Agriculture. As a third layer of protection, we require anyone wanting to use one of these chemicals to get a water quality permit from us.

man fishing

When used carefully under a water quality permit, chemicals can help maintain the waters we love. Photo credit: Tristan Hervouet via freeimages

Water quality permits are a legal tool to allow — and limit — a discharge of pollution into the water. Each permit is different and sets specific methods for release, monitoring, and mitigating any potential environmental damage.

When used carefully under a water quality permit, chemicals can help manage the water we need for the way we live.

For example, water management protects:

  • Aquatic habitat
  • Human and pet health
  • Agricultural purposes
  • Livestock
  • Commerce and navigation
  • Boating
  • Recreational and commercial fishing
  • And much more

The prolific overpopulation of noxious and nuisance plants threaten the waterways Washingtonians know and love. Toxic algae can be dangerous to people, wildlife, and pets. We carefully consider and evaluate all potential solutions for managing Washington waters. The environmental review we’re currently seeking comments on is part of that ongoing evaluation.

Our current environmental review

Variable-leaf milfoil in Blue Lake. It's green tubular fuzzy looking strands floating underwater.

Variable-leaf milfoil in Blue Lake.

We recently completed our draft of a new environmental review for our general permits for managing Washington waters. This review, called a Supplemental Environmental Impact Statement (EIS), helps us determine the potential environmental impact of certain chemicals used to treat unwanted plants and algae. Now, we want your feedback on our draft before we finalize the report.

Send us your comments

We are always seeking more environmentally-friendly ways to manage Washington waters. This environmental study is pivotal to that search. Our goal is to give better tools to those tasked with managing our waterways. We want solutions that target the unwanted plants and algae, and reduce impacts to neighboring plants and animals. We also want solutions that are effective and have a low risk of unwanted plants developing a resistance to the chemical.

Protecting the health of the native ecosystem is our top priority. New information is learned all the time, so it’s important to continually review what we permit with the best science and technology available.

This environmental review is neither a permit nor a decision, but it will inform decisions we make around aquatic plant management in the future.

Man icon with chat bubble

We are now accepting comments on our environmental review of the chemicals used in these two permits. We will take input on the Draft SEIS for Aquatic Plant Management until 5 p.m. on June 6, 2017.

Submit comments using our online form.

We will also accept comments by mail:

Nathan Lubliner
Washington State Department of Ecology
PO Box 47696
Olympia, WA 98504-7696

algae collage, showing several bodies of water, all green with algae.