Toxic Tire Chemical Found at Dangerous Levels in Eureka Parking Lot Runoff
Press release from Humboldt Waterkeeper & California Coastkeeper Alliance:
A recent stormwater sampling effort in Eureka revealed a troubling trend in area parking lots: Even in periods of relatively light rain, high concentrations of salmon-killing toxic compounds are being flushed directly into local creeks and Humboldt Bay.The results come from a pilot project recently conducted by Humboldt Waterkeeper. The organization collected water samples from two Cal Poly Humboldt parking lots in Arcata and from the Eureka Target and Costco parking lots. The water samples were testing for a compound that has recently been discovered to be particularly toxic to coho salmon, which are listed under the federal Endangered Species Act.[Stock photo by Tyler Menezes on Unsplash]
The pollutant in question, known as 6PPD, is used in tires to help maintain their integrity. As tires break down from normal wear and tear, 6PPD is released and reacts to ozone in the air and transforms into a compound known as 6PPD-q. The samples collected at the Cal Poly Humboldt lots after a relatively heavy rain showed concentrations of 130 ng/L, which is higher than the 95ng/L threshold above which coho mortality increases significantly. The Eureka Costco parking lot sample showed much higher concentrations – 340 ng/L – while runoff from the Eureka Target parking lot was even higher, 430 ng/L, or more than four times the lethal concentration for coho salmon.
“Recent scientific discoveries have zeroed in on this pollutant as a significant driver of the steep declines in coho populations, and our pilot study shows that it’s not just a concern in major metropolitan areas,” said Jennifer Kalt, executive director of Humboldt Waterkeeper.
Caltrans and the Department of Toxic Substances Control gave an in-depth presentation to the State Water Resources Control Board in December 2024 about the dangers of 6PPD-q to humans and wildlife. In the presentation, Caltrans pointed to bioswales as a proven treatment option for significantly reducing the concentration of this and other toxins from roadway runoff. Bioswales collect runoff that slowly infiltrates into the soil, removing pollutants before they reach creeks and other waterways.
“Tire manufacturers are searching for a less-toxic substitute, but there’s no guarantee that new chemicals will be a good solution. Thankfully, there are relatively low-tech, low-cost approaches that could significantly reduce the amount of 6PPD-q making its way into coho-bearing streams,” added Kalt.
Runoff from impermeable surfaces like parking lots is a major contributor to water pollution. California Coastkeeper Alliance, of which Humboldt Waterkeeper is a member, is sponsoring AB 1313 (Papan) to help address this concern by requiring the State Water Resources Control Board to create a statewide Commercial, Industrial, and Institutional Stormwater Permit. As drafted, the bill encourages collaboration between stormwater dischargers, like big box stores, and local governments to develop bioswales in strategic areas to intercept parking lot runoff. This nature-based solution would make a big difference in reducing microplastics and other pollutants in waterways.
“It’s concerning to see this level of 6PPD-q in runoff in a relatively small, rural city like Eureka,” said Sean Bothwell, executive director of California Coastkeeper Alliance. “These results make it even more urgent for statewide action on this issue. Every community deserves access to clean water, and AB 1313 provides the framework to start cleaning up polluted runoff throughout the state.”
Research indicates local governments spend between $18–$46 per household for stormwater permit compliance. AB 1313 would shift some of that burden to private sources of pollution, like large commercial parking lots, and encourage private companies to collaborate with local governments to create regional solutions that will reduce pollution in local waterways.
“AB 1313 would require commercial properties to take responsibility for their contribution of stormwater pollution,” said Assemblymember Papan. “A statewide commercial stormwater permit would require compliance through the development of onsite natural infrastructure or through investment in local community stormwater management, treating stormwater as a resource instead of a liability.”
The Humboldt Bay area is relatively rural, and its tributaries provide important habitat for juvenile coho salmon. Removing toxins like 6PPD-q from area streams would improve water quality for area residents as well as for struggling salmonids. These recent water samples point to the need for more study, as Caltrans’ current assumptions likely underestimate the impact of this chemical on streams even in relatively rural areas.
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Its a parking lot, a simple parking lot. And we are supposed to believe the runoff is killing all the Coho Salmon ? Get rid of cars ? Humans ?
BTW, the bay is full of them right now, jumping everywhere.
What points are you making exactly?
Because parking lots are not complex they can’t be a source of toxins?
You are misunderstanding, maybe intentionally, no one claim that this chemical is “killing all the coho salmon”
Uh that’s what the propaganda that I read leads me to believe
Because its a freaking parking lot. There will always be things in that asphalt that comes from the rubber in the tires. No way around it. Some oil here and there, brake fluid, dust from brake pads and clutches.
So do they want us to stop driving our cars ? Not going to happen.
And here is a interesting note for all you enviros who think electric cars are some kind of answer. Electric cars are VERY heavy and the tires wear at a much faster rate. Putting more rubber compounds into our environment. In the end, they are dirtier than gas cars. Super expensive to work on. Hard to find the people who can do it and just what do you do with these giant battery piles of junk when they are worn out ?
Not to mention what it takes to mine all the toxic metals to make the GIANT BATTERIES
IMHO:
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Sighs… er ‘toxic’ tire compounds are found on ANY parking lot, road, highway, freeway, back roads, driveways, sewage plant discharge, airport runways.
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Then if you go further, Asphalt breaks down and releases oils and tars. Concrete releases alkali compounds. Dirt roads contribute silt. Gravel roads contribute alkali compounds. Brake compounds release toxic grit. It goes on.
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Hmm… I wonder what the Eureka City Council… ‘green paint’ is contributing… that green stuff has to go… ‘somewhere’.
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Meanwhile: AB 1313… Papan… a SF Politician.
It’s just another regulation… to add to the list.
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California has a large number of regulations, making it the most regulated state in the US. Specifically, the California Code of Regulations contains 420,434 restrictions as of 2023. This is more than double the national average of 135,000 regulations.
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Go figure.
California is The Rules State.
Seems like 101 would generate tire dust too..probably more that Target. Also it makes sense that light rain would have higher concentrations, there’s less dilution. Big rain, big flush
The question I have is, why are Cohos affected and not Steelhead or Kings? I mean, sure, they’re different species, but not profoundly different. How do the Coho do it up in Oregon? There’s videos of Cohos crossing flooded roads running urban streams up there…
Maybe these big box retailers should be required to get licensed along the lines of Weed Farm-Destroyer of the Environment
Because the 6PPD-quinone and thresholds for toxicity are much higher for trout than the salmon. Or other species. Some fish don’t seem to be bothered at all in some studies. Coho are the most sensitive, so that’s what clean up and alternatives efforts are going to use as a goal line. The issue is not new, nor unique to us, but global. Seems to be higher in colder climates too. Think our numbers are high? Eastern Asia is off the charts in some places, microplastics in particular. But 6PPD is the most toxic to fish, but by far not the only compound or material used in tires of any type.
Fortunately the Coho are not schooling up at the edge of the parking lots — I’m all for reducing pollution and toxic runoff but a more realistic measure of exposure would be to grab a water sample 100’ downstream from where the storm drains discharge into the waterways.
Samples are. In the article links to the presentation, it notes various bioswales (e.g. roadside collection points) and other monitoring sites throughout the state. Avenue of the Giants as well as Highway 1 were sampled. Parking lots. Freeway drainages, road run off. Lots of places. Parking lots should be expected to have higher numbers from constant traffic. Nothing is said about banning anything rather alternatives provided in the report from the major tire manufacturers. Which by their own accord, are more of a “maybe” and “it’s going to be a while for anything to happen because what do we do with all the used tires?”. I did note that graphene was suggested. That’s a rather up and coming material for everything from tires to solar panels and insulation, with a lot of study being done with it. We’ll see what happens. But before anything gets banned, I’d at least expect that dead coho tissue would be sampled to note what actually killed them, and go after that.
Breaking: Coho salmon not actually spawning in the Target lot.
The toxin? Diluted long before it hits a creek. Alarmism like this doesn’t protect wildlife—it just erodes credibility.
Once again the cause is obvious as is the solution.
Mainly bike tires.
Bicycle tires are the worst offenders, a close second are Crocs and Birkenstocks.
“A statewide commercial stormwater permit would require compliance through the development of onsite natural infrastructure or through investment in local community stormwater management, treating stormwater as a resource instead of a liability.”
A statewide commercial stormwater permit would require compliance through the development of more draconian state sanctioned fees, fines, and years long waiting periods for license approval and a mass reduction in new business or through forced compliance of businesses to pay said fines and fees as a way to further steal from taxpayers money already allocated for stormwater management, treating stormwater as cash cow for the state instead of fixing existing infrastructure, which is a not a liability to the state.
That tax already exists. It’s $1.75 per tire (along with an extensive list of various other things you pay taxes on). Did you model the fee use explanation after the official one?
“Fee revenues are used to fund programs that promote recycling and other alternatives to landfill disposal and stockpiling of used tires, and for the mitigation or remediation of air pollution caused by the decomposition of tires in this state”
B.S. Humboldt state who misidentifies fish in our local river and fish in our ocean these jokes need to hit the road with there propaganda learned crap. I’ve fished in our local rivers since I’ve been a kid I have watched our coho numbers explode in the last few years if you want proof of spawning coho go to headwaters trail head in January and February you’ll see dozens of uncounted coho that have successfully spawned in the creek. What else are these brainwashed liberals gonna come up with. It’s just another way for our state to control and regulate our means of transportation and life libs dems and non locals leave our county no one wants you here.
Robert f Kennedy Jr is the founder of the Water Keeper Alliance, of which Humboldt Bay Keeper is associated. Just noting that for the Trump voters out there, and the Trump haters.
I think that we can agree, on both political sides that keeping toxins out of the water is a good thing. Monitoring and testing is not sexy and doesn’t get a lot of attention but I appreciate the people doing the work.
High concentrations of salmon-killing toxic compounds are being flushed directly into local creeks and Humboldt Bay daily…
Brembo develops brakes with almost no brake dust and less wear https://arstechnica.com/cars/2025/05/brembos-new-brakes-cut-particulate-emissions-by-90-percent/
That is the exact same chemicals running off the highway into the rivers every time it rains.
Its been claimed that a new diesel engine sold in CA is so cinched down on emissions that they actually vacuum up and filter other road dust like tire particulates, leaving their space cleaner than before, but producing greater amounts of CO2, and burning more fuel than their earlier engines with the same displacement. I’ve heard that modern gas engines actually emit more particulates now than new diesels. Exhaust filters for gassers coming soon.
the first 2 paragraphs of their article sums it up and the word “potentially” says it all. So somehow this contaminant is the recent, as in the past few years, cause of the decline of an endangered species. yet the use and subsequent deposition of the contaminant is not new and has been used in all automotive tires since the 1960s. its hard to have any respect for this group that just wants to squeeze money of certain entities so they can pay themselves. their tax returns are public information. most developments don’t have the ability to add a bio swale and therefore have to give them money to avoid a lawsuit. I find it interesting that other salmon, that are not listed on the Endangered Species Act, are not as affected by this contaminant, just the currently listed one.