Antifouling boat paint laws

Possible copper-based antifouling paint ban postponed

As a result of our third report to the Legislature, the restriction on copper-based antifouling paints will not take effect in 2026. We will continue to study scientific literature and submit a new report by June 30, 2029. Learn more about why this law is postponed.

In 2011, Washington adopted the Antifouling Paints Law to gradually phase out copper-based antifouling paint. Antifouling boat paints prevent marine plants and organisms from damaging boat hulls. Some paints work by continuously releasing chemicals into the water (most commonly copper), which prevent organisms from attaching to boats. Other paints make it easier for fouling organisms to dislodge. Copper and other toxic chemicals from these paints can also be harmful to fish and other marine life.

Irgarol (also known as cybutryne), is another ingredient added to make boat paints more effective. It's been found to be more toxic and harmful to marine life than previously believed. As of Jan. 1, 2023, irgarol paints are banned for use on recreational vessels.

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Two people wear respirators and plastic suits to paint a boat hull

What does this law do?

As part of the law, we agreed to study antifouling paints and how they affect marine organisms and water quality. We studied peer-reviewed science on antifouling paints and their hazards. These reviews showed that non-copper antifouling ingredients might be more environmentally harmful than copper. As a result, the law phasing out copper paints is postponed.

Learn more about our studies: 2024:

Why is this law postponed?

In our third report to the Legislature, we developed hazard-based criteria to determine whether antifouling chemicals are safer than copper. We also identified data gaps and conducted performance testing to evaluate effectiveness of various alternatives. We found that:

Biocidal antifouling alternatives have remained essentially unchanged since our previous report in 2019.
Only one antifouling chemical, Sea-Nine, can be considered “safer” than copper, but we lack sufficient data to draw conclusions about its effectiveness.

We also reviewed research and studies on non-biocidal antifouling alternatives. As they are still in early development, most of the needed scientific information on environmental impacts is not yet available. We will continue to study scientific literature and submit a new report by June 30, 2029.

Why are we studying antifouling boat paints?

Elevated copper in marine environments can cause acute toxicity such as mortality of aquatic species. Chronic exposure can lead to adverse effects on survival, growth, reproduction as well as alterations of brain function, enzyme activity, blood chemistry, and metabolism.

While copper is the most common toxic chemical that antifouling boat paints release into the water, our studies also looked at other non-copper ingredients currently on the market, including:

Zinc pyrithione.
Irgarol (cybutryne) (banned as of 2023).
Sea-Nine (DCOIT).
ECONEA (tralopyril).

There are also non-biocidal options available, such as boat washes, sonic cleaning systems, liner systems, and drive-in dry docks. However, some options are not readily available, and we do not know the performance and tradeoffs of these options yet.

Frequently asked questions

When boats are kept in marinas, lakes, and other water bodies, they are exposed to organisms like bacteria, algae, mollusks, barnacles, and mussels. When these organisms grow and colonize on the bottoms of boats (hulls), it’s called fouling. Fouling makes boat hulls rougher, which increases drag, fuel consumption, and reduces speed.

Antifouling boat paints prevent organisms from growing on boat hulls.

Copper is highly toxic to fish and other aquatic species. It interferes with their sense of smell, making them more vulnerable to predators. It also reduces their ability to return to their spawning streams. Young salmon are especially susceptible to the effects of copper.

Copper contaminates our waterways through:

Antifouling boat paints.
Copper brakes (also banned).
Pesticides.
Water pipes.

As part of our 2019 review, we used scientific modeling to predict how antifouling ingredients might function in Washington marinas. We concluded that Irgarol is more dangerous to the environment than previously believed.

In 2020, Washington adopted a prohibition on irgarol law (Chapter 70A.445.070 RCW) that bans the use of irgarol paints on recreational vessels as of Jan. 1, 2023. This law prohibits:

Sales of boat paints containing irgarol.
Application of hull paints containing irgarol.
Sales of new boats painted with irgarol paints.

These restrictions are part of a worldwide effort to phase out Irgarol paints for commercial and recreational water vessels. In addition, beginning Jan. 1, 2023, the Environmental Protection Agency (EPA) will not allow paints containing Irgarol to be registered and sold in the United States.

Used boat sales are not affected by the new restriction, and boat owners are not required to remove existing Irgarol paint.

Contact information

Iris Deng
Natural Resource Scientist
360-480-6555
iris.deng@ecy.wa.gov