Re-posting from Mark Mattson's Blog

Wesleyville, Lake Ontario and the Price of Silence

I drove past Wesleyville yesterday. It is a quiet corner of Ontario, a small village framed by farmland and the open water of Lake Ontario. What catches your eye is not the homes or the shoreline, but a towering smokestack rising alone at the water’s edge.

The stack belongs to a power plant built decades ago that never produced a single watt of electricity. It sits empty and unused—a ghost on the waterfront, a monument to an energy future that never arrived. Around it lies one of the last large stretches of relatively untouched Lake Ontario shoreline.

It’s the kind of place that makes you stop and ask questions. Why was this built? Why was it abandoned? And now, what happens next?

This month, the Ontario government provided its answer. The Wesleyville site, a 1,300‑acre parcel just west of Port Hope, is slated to become the largest nuclear generating station in the world. At 10,000 megawatts, the project is being promoted as a “clean” and necessary response to Ontario’s growing energy needs.

But behind the polished messaging is a reality Ontarians deserve to confront openly: this project would lock Lake Ontario into a level of ecological risk we have never seriously debated—and may not be able to undo.

A Lake Already Pushed Too Far

Lake Ontario is not an empty canvas. It is already the most nuclear‑industrialized body of freshwater on the planet.

Across the Great Lakes basin, there are 38 nuclear reactors. Ontario operates nearly half of them, with 10 located directly on the north shore of Lake Ontario. Alongside these reactors sit thousands of tonnes of high‑level radioactive waste, stored in facilities described as “temporary,” yet positioned right on our shorelines.

Building a massive new nuclear complex at Wesleyville is not just an addition—it is an escalation. It further concentrates industrial risk along a lake that supplies drinking water to tens of millions of people in Canada and the United States and supports one of the most important freshwater ecosystems on Earth.

At some point, we have to ask a simple question: how much is too much?

Treating a Lake Like a Machine

One of the most immediate threats comes from the cooling technology likely to be used. The proposal relies on once‑through cooling systems—the same approach used at Pickering and Darlington.

Once‑through cooling treats Lake Ontario as a piece of industrial equipment rather than a living system. Massive volumes of water are sucked into the plant to absorb heat and then discharged back into the lake at higher temperatures.

The consequences are well‑documented. Fish are trapped against intake screens and killed by pressure. Smaller organisms—fish eggs, larvae, and the tiny species that form the base of the food web—are pulled into the system and destroyed. At Darlington, more than a million fish have been killed in a single year through this process alone.

At the scale proposed for Wesleyville, the plant could draw in the equivalent of an Olympic‑sized swimming pool of lake water every few seconds, day and night. This relentless extraction would steadily erode nearshore ecosystems that fish, birds, and coastal communities depend on.

Heating the Lake

The harm doesn’t end when the water leaves the plant.

Discharged water can be more than 10 degrees Celsius warmer than the surrounding lake. These artificial “hot zones” disrupt fish migration, interfere with spawning, and can cause direct heat stress or death in species that cannot adapt quickly enough.

At the same time, warmer water creates ideal conditions for invasive species and pathogens—organisms that already pose one of the greatest threats to the Great Lakes. Once established, these invaders are nearly impossible to remove.

The Myth of “Clean” Water

Nuclear power is often called “clean” because it does not emit carbon dioxide while generating electricity. But that framing ignores what happens to water.

Tritium, a radioactive form of hydrogen, is routinely released from nuclear facilities. Ontario’s allowable limit for tritium in drinking water is far higher than standards used elsewhere, including in the European Union and parts of the United States.

Radioactive materials also accumulate in living organisms. As they move up the food chain, concentrations increase—meaning the risks are not evenly distributed. They are borne most heavily by those who fish, harvest, and live closest to the lake.

Calling this “clean” energy without acknowledging these trade‑offs is misleading at best.

A Choice, Not an Inevitability

The Wesleyville project entered the federal Impact Assessment process in early 2026. That process exists for a reason: to ensure that decisions of this scale are tested in public, with evidence, transparency, and accountability.

At a minimum, Ontarians should demand two things.

First, any new nuclear development must abandon once‑through cooling in favour of modern closed‑cycle systems that use far less water and dramatically reduce harm to aquatic life.

Second, the province must justify—openly and honestly—why a nuclear expansion projected to cost hundreds of billions of dollars is preferable to a diversified energy strategy that includes renewables, storage, efficiency, and distributed power systems that can be deployed faster and with far less ecological risk.

Lake Ontario is not a cooling pond. It is our drinking water, our shoreline, our food source, and a shared responsibility across borders and generations.

Once we cross certain thresholds, there is no reset button. Wesleyville may look quiet today—but the decisions made there will echo for decades.

What You Can Do

Ontarians should demand a full, transparent public review of the province’s energy plan through the Ontario Energy Board and environmental assessment processes before irreversible commitments are made.

This issue also demands international attention. The International Joint Commission, the Canada Water Agency, and elected officials at every level should be engaged now—not after construction begins.

There will only be one chance to get this right. Silence is a decision too—and it may be the most expensive one of all.

By Mark Mattson