Over the past two years, the U.S. Army Corps of Engineers has dredged up tens of thousands of cubic yards of sludge, mud and sand from the bottom of Duluth Harbor and dumped it along the Lake Superior shoreline to try to raise beach fronts and protect homes from record high water levels.

It all may have been illegal.

The Minnesota Conservation Federation and the state of Wisconsin sued the Army Corps in 1976, the last time it tried to use dredgings from Duluth Harbor to bolster the shorelines of Lake Superior. The case was settled in federal court shortly before it was set to go to trial. That settlement document, however, seems to have disappeared.

Regardless, it remains in place today and prohibits dredgings from Duluth Harbor — polluted with heavy metals — from being exposed to Lake Superior or its beaches, said retired lawyer Grant Merritt, who was Minnesota's first Pollution Control Agency director and represented the Conservation Federation in the case.

"It's completely illegal," Merritt said. "I could sign an affidavit as to what was said in that settlement. There is no doubt this was binding."

The St. Paul District of the Army Corps of Engineers, which included Duluth at the time, is searching its archives, but as of Tuesday has found no record of it, a spokesman said.

No agency or court in Minnesota can seem to find the terms of that settlement either, as old court records have been filed away in federal archives. Judge Miles Lord, who signed off on it, died in 2016. The Corps' Detroit district, which now encompasses Duluth, found no details on the case.

The U.S. District Court sent records of the case to an archive in Chicago. But that archive has been closed for months because of the coronavirus pandemic.

Meanwhile, dredging continues and Merritt has been racing to find proof that the settlement he helped negotiate back then is binding today.

"It's ridiculous," he said. "Has it been destroyed or is it in the national archives? If it's there, let's get it."

The Army Corps dredges the harbor often to keep it open for navigation. Last summer, with permission from the Minnesota Pollution Control Agency (MPCA), it began depositing some of that material on the lake side of Park Point, also called Minnesota Point. The MPCA has given the Corps a conditional water quality certification to place up to 1 million cubic yards of dredge spoil on the point over five years, so long as the Corps meets certain standards. Some of it will also be used to expand Interstate Island within Duluth Harbor to try to save one of the last known colonies of common terns in Minnesota.

The Army Corps and Duluth residents have argued the need for the dredge fill is urgent, as Lake Superior levels have reached record highs and caused erosion and property damage for many of the 300 homes, hotels and businesses sitting on the skinny strip of land.

The fill is "a godsend" for homeowners, said Hamilton Smith, who has lived on Park Point for nearly 50 years.

"It really does make a difference, when the beach disappears and the waves are rolling in," Smith said.

He said homeowners are aware of the old lawsuit, but he believes the issues raised four decades ago don't reflect the situation today. The MPCA and the Corps have sampled the material and found it didn't pose a health risk, he said.

"If that material passes the human health risk standards, we'd like to have it on Park Point," Smith said. "Unless we don't trust the MPCA. But you've got to trust somebody."

Old worries renewed

Water levels in the Great Lakes were also high in the mid-1970s, and property owners along the point were losing land to erosion, news articles from the time show. The Army Corps decided to try a "beach-nourishment experiment" using the sand and mud it dug up to replenish the shore.

The Conservation Federation sued, arguing that the project would release mercury and lead, among other dangerous pollutants, according to articles from the Minneapolis Star, the Minneapolis Tribune and the Associated Press. The Wisconsin Attorney General joined the lawsuit in December 1976, saying the project would carry toxic substances into Wisconsin waters.

The Wisconsin State Law Library said Tuesday that it is searching for any records it may have of the case.

A search of the Star Tribune's archives could not find any mention of how the case was resolved, only that the Conservation Federation and Wisconsin had successfully blocked the fill from going to the beaches.

Retired lawyer Tom Larson, who represented the Army Corps in the case and now lives in Nebraska, said he can't remember details of the settlement. But he remembers reaching a deal and can't believe records have been so hard to find. If the agreement was binding, as Merritt says, then the Army Corps should have the records, he said.

"If you agree to something, that means you're responsible for complying with it," Larson said.

Merritt said he fears the same pollutants that lay in the harbor 40 years ago, deposited by Duluth's old industrial giants, remain.

Even clean sand that's dredged up and released causes too much turbidity to meet state water quality standards, said Willis Mattison, a retired ecologist who worked at the MPCA for 28 years.

Both Mattison and Merritt called on their old agency to conduct a more thorough assessment of the risk and more rigorous monitoring of the dredge spoil.

One of the key problems, Mattison said, is that the man-made structures built to open the harbor to navigation cut off the natural flow of sand. They have flooded one side of the shore with sand while starving Park Point, he said.

"Right now our solution to this man-made problem is to dump dredge spoil, which just causes other problems," Mattison said.

MPCA officials did not respond to a request for comment.

Anna Hotz, an MPCA supervisor, wrote in the decision approving this year's dredge placement that any pollution problems are "anticipated to be localized, short-term in nature, and of no long-term impact to the water quality of Lake Superior."