A sign announcing the future site of the Deep Geologic Repository Project. (Steve Friess)

If there was an off-key moment during the otherwise flawlessly executed trip to the U.S. Capitol this spring by the new Canadian prime minister, Justin Trudeau, it might have come when he was cornered by Rep. Debbie Dingell.

“We never want to see nuclear waste in the Great Lakes,” the freshman Democrat from Michigan sternly told Trudeau during a visit to the office of House Minority Leader Nancy Pelosi (D-Calif.).

Trudeau knew what Dingell was talking about. A few weeks earlier, his administration delayed an expected final ruling on whether Ontario Power Generation (OPG) could blast an area twice as big as the White House in a hole as deep as four Washington Monuments and then dump and seal inside 50 years’ worth of low- and intermediate-level radioactive waste amassed by the province’s three nuclear power plants.

The material, which will take thousands of years to decay to levels that are not toxic, would reside beneath layers of rock that geologists say have not moved in tens of millions of years. The planned Deep Geological Repository is controversial in part because it would sit about a mile from the bottom of Lake Huron. And that has prompted widespread activism throughout the Great Lakes region among those who see the concept as too risky for the 40 million people who rely on this, the largest freshwater network in the world.

Trudeau has remained tight-lipped on the plan, much to the frustration of many in both the United States and Canada.

Jan Thomas, of Port Huron, holds a sign protesting a proposed nuclear waste dump site on Lake Huron, Sunday, Aug. 16, 2015 during the International Rally to Protect the Great Lakes at Pine Grove Park in Port Huron, Mich. (Andrew Jowett/AP)

Dingell left her Trudeau visit, she said, a bit baffled and frustrated. “All he said was that he truly cares about the environment,” she said. “I didn’t know what to make of that. I’m not going to read into it. I just don’t know.”

The plan is supported by dozens of scientists, including those who participated in a government-appointed independent review panel that approved of the plan. The 2,231-foot hole would go far below the water table and into layers of rock so ancient that they have not moved in more than 50 million years, they say. It is the best solution available, they say, to ensure that the material, now stored in canisters at the surface, is kept away from humans well into the uncertain future.

That’s not enough for environmentalists and political leaders on both sides of the Great Lakes. “No matter what process is followed, abandoning radioactive nuclear waste in the Great Lakes basin will always be a bad idea,” said Beverly Fernandez, spokeswoman for Stop the Great Lakes Nuclear Dump, who lives in Southampton, Ontario, about 30 miles north of Kincardine.

The decision ultimately will fall to one person, Canada’s freshly installed environment minister, Catherine McKenna. The provincial government approved the plan last year after the independent review panel endorsed its safety. Now the federal government, specifically McKenna, must either green-light or kill it. She had promised to rule by March, but in February she asked OPG for more information; the utility said in April that it would comply by the end of the year.

OPG spokesman Bill McKinlay insisted that the company is “happy” to oblige McKenna, repeating the word more than a dozen times in 10 minutes.

“We’re happy to respond to them,” McKinlay said. “We’ve been open and transparent through this whole process, and we’re happy to do what we can to help people understand it.”

Opposition to the project, though, has swelled. More than 180 county boards, city councils and other local elected bodies near the Great Lakes in both countries have passed proclamations urging a veto of the plan. Dingell was among 32 members of Congress who signed a bipartisan letter to Trudeau asking him and McKenna to reject it. The GOP-dominated Michigan Senate unanimously passed a resolution calling on the White House and Congress to intervene under the Boundary Waters Treaty. (The White House referred questions to the State Department, which declined to comment on the issue.)

Some of those U.S. politicians, though, support the long-delayed effort to bury the United States’ high-level nuclear waste at Yucca Mountain, outside Las Vegas.

Dingell doesn’t see that as a contradiction. “This is different,” she said. “We’ve got to find a location that doesn’t impact large populations of people. A mountain that is in an isolated place is a better place than water that is 20 percent of the freshwater in the world. If there’s a leak or an accident at Yucca Mountain, it’s in an isolated area.”

Yet for Canada, like the United States, the issue remains one of the biggest headaches for nuclear power generation. Nuclear power is one of the cleanest, cheapest sources of energy, especially in places like Ontario, where coal-burning power plants were banned in 2003. But the conundrum of what to do with the waste persists, even after more than half a century of nuclear-fueled electricity.

Low-level waste includes mops, brooms and clothing, which are expected to reach safe radioactive levels in about a century. Intermediate-level waste includes hardware such as pumps, filters and other machinery that has been in direct contact with nuclear fuel and won’t return to safe levels for at least 10,000 years. (High-level waste includes spent uranium fuel rods; such material would not be sent to the planned repository.)

The Bruce Energy facility here in Kincardine is the world’s largest nuclear-power-generation site, with eight of the province’s 20 nuclear reactors. Since the early 1970s, the Bruce site has stored the low- and intermediate-level waste for all of Ontario’s power plants in above-ground bunkers and vaults, which are evidenced only by dozens of cement caps of various shapes arrayed in neat rows across a concrete plain near the reactor buildings. OPG and Bruce officials have long assured the public that such storage is safe, and they’re not backing away from that contention.

Yet it is an expensive long-term solution that relies on hundreds of future generations to maintain and defend it. “You look at parts of the world that seem to go from reasonable governments to chaos, and I don’t think you can predict what kind of society will exist hundreds or thousands of years from now,” said Derek Martin, a professor of geotechnical engineering at the University of Alberta and a key member of the research team that developed the plans for the Kincardine site. “When you look at the geological history of the area, it’s been so benign in geological activity in the last tens of millions of years. I don’t know how you could find a safer place to put it.”

The city of Kincardine, which received more than 600,000 Canadian dollars (about $465,000) a year between 2004 and 2014 for agreeing to host the repository — the stipends stopped after opposition grew and progress stalled — stands to benefit from additional regular payments as well as new jobs.

Mayor Anne Eadie pushes back at opponents who question the plan’s safety.

“It just keeps coming back to that main question,” she said. “Is it safer where it is right now? We had a tornado in a town near here three or four years ago . . . and that could’ve just as easily been in Kincardine. It was a devastating tornado. Wiped out the town. Is this stuff safer where it is now, or is it safer 650 meters down in rock that hasn’t moved in eons?”

Like Trudeau, the environment minister, McKenna, has publicly said nothing specific. But opponents are pleased that OPG has been asked to provide information about potential alternative sites — the company never researched any others, in part because it already owns the land where the repository would go — as well as to explain the “potential combined environmental effects” of both the OPG repository and a similar repository for high-level nuclear waste under consideration by Canada’s government. Three of the nine communities that have expressed interest in hosting the high-level waste repository are near Kincardine and, thus, almost as close to the lakeshore.

“The alternative-sites investigation should have been part and parcel of this thing from the beginning,” said Kevin Kamps of the national environmental group Beyond Nuclear, who has been fighting the OPG repository since 2001.

Kamps and Fernandez say they question the certainty of the scientists who have vouched for the safety of the site. The activists note that there are three other repositories in the world that handle nuclear waste, two in Germany and one in New Mexico, and all have had leaks or problems despite similar assurances that they were foolproof. Another is under construction in Finland, and several other countries including Sweden, Japan and Britain are considering building them.

Opponents of the plan don’t have a solution for what to do with the waste — and insist it’s not their job to figure it out.

“If it must be buried, bury it outside of the Great Lakes basin and far from people, far from water,” Fernandez said. “One thing is for sure: We shouldn’t bury this lethal material beside the source of drinking water for 40 million people in two countries. We will never know if there has been a leak until it’s too late.”