Maybe Canada should levy a tumbleweed tax on the U.S.

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Emily Waugh is a Toronto-based writer and past lecturer in landscape architecture at the Harvard University Graduate School of Design.

When Vladimir Menkov lived in B.C.’s Okanagan Valley, he figured his south-facing fence would be enough to protect his yard from the tumbleweeds that blew up from Washington each fall. But as he explained on Quora, the website where he has answered more than 1,700 questions like “Do bears and native North American animals cross the U.S.-Mexico border or even the U.S.-Canada border?”, Mr. Menkov discovered that if he didn’t patrol the fence line regularly, the tumbleweeds would roll on top of one another, stacking up to form a launching ramp for the “new arrivals” to jump the fence entirely. In idle moments Mr. Menkov wondered what would happen if someone were to load those same tumbleweeds in the back of a truck and try to drive across the border.

Or fly. Around this time every year, 2.6 billion migratory birds cross the United States border into Canada – no certificate of origin, no customs declaration required. But try to drive over the Ambassador Bridge with a container of leftover duck enchiladas from Vecino on 3rd Street in midtown Detroit? No way. Restrictions aimed to reduce the spread of highly pathogenic Avian influenza (which has impacted more than 17 million domestic birds in Canada to date) explicitly prohibit restaurant food or leftovers containing poultry to enter Canada. Don’t try to mail them either: Meat items (including poultry) may not enter Canada by mail or courier.

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From the waters of the Detroit River alone, Canada has unwillingly imported enough industrial waste, alien chemicals and phosphorous-laden wastewater to declare Lake Erie dead in the 1960s; millions of gallons of oil, including a spill in 1948 that killed 11,000 ducks and geese; lube waste; diesel fuel; greaseballs; raw sewage; football-sized chunks of animal fat, hair and small pieces of garbage; PFAs, PFOs, PCBS, PAHs, and VOCs; Brown Bullheads with both internal and external tumours; mercury, copper, iron, zinc, cadmium and lead; and an unknown amount of limestone aggregate tainted with Manhattan Project-era uranium.

Add up the ecological, cultural and economic toll of the incidental imports that blow, fly, tumble, roll, swim, float, hitchhike, spill and bloom across our 8,891-kilometre border with the United States, and Mr. Menkov’s tumbleweed paradox shifts from a hypothetical “what if,” to a very real “how much?”

Let’s start with the tumbleweed, which is essentially a rolling seed bomb of invasive Russian Thistle. This noxious weed first snuck into South Dakota in 1873 with a shipment of contaminated flaxseed from Siberia and continued to freight-hop its way through the western U.S. before importing itself into Canada 20 years later. Invasive weeds in plants and pastures (including jointed goat grass, woolly cup-grass and other “weeds of economic concern” that have arrived via the U.S.) cost Canada an estimated $2.2-billion every year through reduced crop yields and quality, removal, and weed control.

The emerald ash borer, according to this genteel description from the Government of Ontario, “likely crossed into Ontario at Windsor after establishing in the Detroit area.” It has since girdled and killed millions of ash trees and would cost an estimated $1.4-billion in removal through 2035 if unregulated. Black ash, which Indigenous communities have used for generations to make baskets, canoe thwarts, and cradleboards, is now listed as endangered in Ontario.

Invasive moths, plant hoppers and other winged pests such as the carnation tortrix and spotted lanternfly have made their way from the United States and threaten Canada’s $1.6-billion fruit sector (by farm-gate value). That’s more bad news for B.C. farmers whose production of nectarines, peaches, wine grapes, apricots, sweet cherries and other tree fruits have already been walloped by heat domes, cold snaps, atmospheric rivers and other climate impacts.

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It’s not only flying pests arriving by air, but fine particulate matter and ambient air pollution as well. Health Canada estimates that anthropogenic air pollution sources (including those that drift across the border from the U.S.) cause more than 15,000 premature deaths each year in Canada, at a cost of $114-billion annually. A 2024 paper published in Science of the Total Environment studied the health impacts of the transboundary air pollution that comes to Canada from the United States, with a specific focus on ozone and fine particulate matter including dust, pollen, soot, smoke, and liquid droplets. The authors attribute one in five particulate matter deaths and more than half of ozone deaths in Canada to U.S. sources.

Twenty transboundary waters flow back and forth between the United States and Canada, making the environmental policies of our two countries intertwined. As I type, all that stands between millions of pounds of invasive silver carp and the Great Lakes (and their $7-billion commercial and recreational fishery) are two electric dispersal barriers in the Chicago River. Not to mention the agricultural runoff and wastewater effluent coming down the Maumee and Detroit Rivers, driving the cyanobacteria algae blooms that plague Lake Erie every summer. I can tell you from personal experience that the foul smell and heaps of bloated fish washing up on shore make the beaches less than inviting.

Whether you prefer Pierre Trudeau’s “sleeping with an elephant” metaphor for living next door to the United States, or Robin Williams’s slightly less diplomatic “nice apartment over a meth lab” version, we feel “every twitch and grunt,” as Mr. Trudeau put it, when our neighbours make a move. Or, with their current administration, every time they revoke, rollback, or flat-out mock a move designed to protect our shared environment.

It has often taken conflict to move forward with shared environmental agreements between our two countries. Acid rain in the 1980s gave us the 1991 Canada-U.S. Air Quality Agreement. The Migratory Bird Treaty Act of 1918 (Migratory Birds Convention Act in Canada), which protects more than 1,000 of the species in flight today, was a crisis response to the decline of migratory bird populations being harvested for sport, sale, and feather trade. It took the destructive power of the sea lamprey, an aggressive, blood-sucking, leathery skinned, primitive, eel-like predator, to jolt Canada and the U.S. into joining together to form the Great Lakes Fishery Commission to save the largest freshwater system in the world from complete devastation. Just saying.

In the meantime, maybe U.S. Immigration and Customs Enforcement could redirect some of its new US$70-billion budget toward killer algae enforcement and removal operations, cross-border carp investigations and detention centres for alien tumbleweeds.