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Toxic Dust Threatens California Salmon Population, Lawmaker Seeks Solution

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A man wearing a grayish hoodie and sun glasses rests his arm inside a boat.
Salmon fisherman Richard “Dick” Ogg poses for a portrait in his boat, the Karen Jeanne, at Spud Point Marina in Bodega Bay, Calif., on Saturday, March 30, 2024. If fisheries cancel California’s salmon season for the second year in a row, Ogg plans to make a trip to Oregon to catch salmon there. (Juliana Yamada/KQED)

For the first time in more than three decades of fishing for salmon near Bodega Bay, Dick Ogg will motor his white and navy boat, Karen Jeanne, north this summer past his typical fisheries in hopes of finding the multicolored species along the Oregon coast.

There aren’t enough salmon left off the California coast for Ogg to sell on Bodega Bay’s historic docks.

“We, as fishermen, have nowhere to turn,” he said.

Fishery managers are signaling they may cancel California’s commercial salmon season for the second year in a row, which means the 71-year-old has two options: temporarily traveling to Oregon to catch salmon or barely making ends meet luring in rockfish and sablefish.

Ogg, often in a gray hoodie and wiry sunglasses, wishes there was a solution for boosting California’s salmon schools. He describes the species as “having one of the greatest spirits” an ocean-fairing creature can have.

“They can take a hook and bend it straight to get away,” he said, remembering countless salmon that escaped. “Maybe that’s what they were supposed to do, having the chance to go up the river to spawn.”


Lawmakers think they have a solution for at least one part of the salmon mortality problem: purifying highway runoff of toxic dust from tires that enters streams and rivers during storms — made worse by human-caused climate change. When the chemical enters waterways, it quickly kills some species of salmon and trout.

Assemblymember Diane Papan (D-San Mateo) recently introduced legislation — AB 1798 — that would mandate the state’s leading transportation agency to devise a plan for naturally removing the toxic tire particles, known as 6PPD-quinone, before they slip into waterways and kill fish. While the state has already asked the tire industry to develop alternatives for the chemicals in every tire sold in California, Papan’s plan seeks to clean up the pollution from the cars already on the road.

A man wearing a grayish hoodie and sun glasses stands in the doorway on a boat with bright blue overalls to the left.
Salmon fisherman Richard “Dick” Ogg stands for a portrait on his boat, the Karen Jeanne at Spud Point Marina in Bodega Bay, Calif., on Saturday, March 30, 2024. Ogg is planning on going to Oregon for salmon season this year, due to California’s shortage. (Juliana Yamada/KQED)

While purifying runoff from tiny, tainted rubber bits won’t entirely solve the salmon die-off, Ogg sees the effort as an “opportunity to do what we can to support the fish.”

The perils to California’s salmon are growing.

A changing ocean, dams blocking migration paths, worsening drought conditions drastically decreasing water flows, and climate-fueled storms further complicate river systems. People are feeling the effects on land, even if they don’t realize it — fishers lose jobs, restaurants turn to farm-grown fish, and tribes who view salmon as part of their cultural identity can’t rely on salmon as a food source.

Sarah Bates, who captains Bounty, a commercial fishing boat docked at Fisherman’s Wharf in San Francisco, said the industry is suffering after years of diminished salmon populations.

A man walks by boats on a dock.
Salmon fisherman Richard “Dick” Ogg walks through Spud Point Marina in Bodega Bay, on Saturday, March 30, 2024. If fisheries cancel California’s salmon season for the second year in a row, Ogg plans to make a trip to Oregon to catch salmon there. (Juliana Yamada/KQED)

“A lot of people are out of work and struggling financially and emotionally,” she said. “But the fact is that these fish are in peril because their river ecosystems are in peril. If we don’t take some steps now, then we might be looking at the final days of the species and the fishing fleet.”

What is 6PPD?

For over half a century, manufacturers have included the chemical 6PPD in the tire-making process to help them last longer. When ozone in the air comes into contact with the chemical, it turns into 6PPD-quinone. The byproduct ends up as toxic dust on roadways. During storms, the chemical gets washed into rivers and streams, where it comes in contact with fish.

Recent studies have linked the death of coho salmon to the chemical. In watersheds near the busiest roadways, researchers found up to 90% of returning salmon in the Pacific Northwest may die before spawning. They also found the chemical in roadway runoff in Los Angeles and creeks in San Francisco and suggested the contaminated bits of rubber kill steelhead trout and chinook salmon.

Chinook salmon (pictured) as well as steelhead trout are being killed by toxic tire dust that produces the chemical byproduct called 6PPD-quinone when ozone in the air comes into contact with the chemical. Researchers found the byproduct in roadway runoff in Los Angeles and creeks in San Francisco. (Patrick T. Fallon/AFL via Getty Images)

Some species, like coho, are susceptible, and the substance diluted in water can kill them in hours. In 2022, researchers found that “significant mortality occurred in coho even when roadway runoff was diluted by 95% in clean water.”

The chemical’s effect on human health is still unknown, according to the U.S. Environmental Protection Agency.

On the Russian River in Sonoma and Mendocino counties, officials counted fewer than 2,000 chinook salmon in December, down from nearly 7,000 in 2012 — a far cry from the more than 150,000 fish that swam the river more than a century ago, said Don McEnhill, executive director of the environmental nonprofit Russian Riverkeeper.

“This is kind of a straw that breaks the camel’s back kind of situation,” he said. “We have created a host of impacts on aquatic ecosystems, and this new stressor, climate change, is putting a lot more pressure on them.”

Last November, the U.S. EPA granted a petition by tribes for the agency to consider establishing regulations prohibiting the manufacturing, processing, use and distribution of 6PPD in tires.

“We could not sit idle while 6PPD kills the fish that sustain us,” said Joseph L. James, chairman of the Yurok Tribe, in a statement.

EPA officials said last fall that addressing the contaminant in the environment “is one way we can work to reverse this trend.”

As a result, the state required the tire industry to give California a list of more than 40 alternatives to 6PPD by last Friday. The state’s Department of Toxic Substances Control has two months to evaluate the findings before providing feedback to the tire companies, but in a statement, it said, “the responsibility to comply falls first on manufacturers.”

“This marks a crucial milestone in our efforts to compel manufacturers to look for safer alternatives to this toxic chemical while ensuring tire safety on California’s roads,” said Meredith Williams, the agency’s director.

‘It’s in every vehicle tire’

Removing 6PPD-quinone from storm runoff is a massive undertaking, but Assemblymember Papan is spearheading the challenge. In March, she introduced legislation mandating Caltrans develop a regional strategy to eliminate the chemicals from stormwater discharge into salmon and steelhead trout habitats.

While tribes call for eliminating 6PPD in tires everywhere, Papan’s bill focuses on removing existing toxic dust from roadways because eliminating the chemicals from tires doesn’t address out-of-state travelers, imported tires or tires already on cars.

Cars and trucks on an interstate highway as seen from an overpass.
Traffic on Interstate 880 toward Oakland flowing with cars and diesel trucks midafternoon on Monday, June 28, 2021. (Joyce Tsai/KQED)

“It’s sort of the first step,” she said. “It’s in every vehicle tire, and we’ve got to find a replacement. In short of finding that replacement, this bill plays a key role in keeping our waterways clean.”

The legislation directs Caltrans to create five pilot projects in San Mateo, Contra Costa, Sonoma, Humboldt and Nevada counties where highways cross salmon and steelhead-bearing waters. The bill also advises Caltrans to create green basins near roads where plants and soil naturally remove the chemicals from runoff before entering rivers and streams.

“We won’t be able to do it everywhere, but as we expand out, we will look at where we can do it in a targeted fashion,” she said.

Caltrans declined to comment because the agency does not comment on pending legislation.

The U.S. Tire Manufacturers Association, representing a dozen companies that operate 57 tire-related facilities across the country, supports Papan’s bill. Sean Moore, who leads the group’s government relations team, said the organization is working with Papan because it could take years for the rules banning the preservative to come into effect, and “in the meantime, it’s important to look at other ways to mitigate concerns related to stormwater more broadly in the environment.”

Environmental groups, like the California Coastkeeper Alliance, also back Papan’s effort, though it is unclear exactly how many salmon and trout in California die daily from exposure to the chemical.

“We need to start taking action, or else these species might go extinct,” the group’s executive director, Sean Bothwell said.

He said filtering out the contaminants from stormwater using natural barriers is just the beginning; other roadway debris, like grease, oil and microplastics, could be treated using the same methods.

More on Climate Change

“It can address all that in one swoop,” he said. “We’re using 6PPD as the poster child of why we need to do this.”

Papan’s solution for reducing salmon and trout dieoff may also have a secondary benefit: reducing flooding during storms, which are only becoming more intense as the world warms.

“We can’t think about our infrastructure as one-trick ponies anymore,” said Hayley Currier, policy manager with the environmental nonprofit Save the Bay.

Because much of the state’s water infrastructure is not ready for future storms, Currier said she hopes the pilot projects prove that creating extra space for tainted runoff to pool into will help save fish species while also reducing flooding.

“Everything has to do multiple things,” she said. “When building our infrastructure, we need to think about climate resilience, and flooding needs to be right up there with fire and heat.”


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