After months of searching, the U.S. Army Corps of Engineers has unearthed a long-lost legal settlement that sets the rules for what to do with the mud and sand it digs out of the historically polluted Duluth Harbor shipping channel.

Now, there's disagreement over how to interpret it.

The case could affect an effort already underway to use dredged material to raise the beaches and protect homes along Duluth's Minnesota Point, which has been battered by Lake Superior's record high water levels. The Army Corps launched the project in 2019 after testing revealed the dredged materials were clean, but environmentalists balked this summer. They argued that the settlement — spurred by a dispute over using the fill to raise the same shoreline in 1976 — barred the release of dredge spoil into the lake.

Strangely, the settlement seemed to be forgotten by all except the lawyers who negotiated it. No agency, court or lawyer in Minnesota could find a record of the agreement until the Corps uncovered it this week.

Here's what it says: In all future dredges, the Army Corps is required to "give good faith and reasonable consideration to the feasibility of on-land dredge material disposal areas," before putting the fill in the lake. The Corps is allowed to consider cost, environmental impact and availability of sites, "along with other relevant factors," as it decides where to put the material.

The Corps was also required to establish a testing program with the Environmental Protection Agency (EPA) and the Minnesota Pollution Control Agency (MPCA) to sample any material it pulls out of the harbor, which it did.

The Army Corps has met or exceeded each of those standards, said Bill Dowell, spokesman for the Corps' Detroit District, which includes Duluth.

"This doesn't prohibit the placement of the material. It requires the Corps, in good faith, to consider a variety of factors," Dowell said.

Grant Merritt, who helped negotiate the settlement agreement on behalf of the Minnesota Conservation Federation, disagrees.

For the past 40 years, the Corps has been able to find feasible inland dumping sites for the Duluth Harbor dredge spoil so pollutants don't wind up in the lake or its fish, said Merritt, who was also the first commissioner of the MPCA.

"So how can they say that they had no feasible or prudent alternative?" he said. "They clearly didn't give good-faith consideration."

It's unclear if the Minnesota Conservation Federation or another environmental group will press the issue or take it back to court.

Lance Ness, president of the federation, said they just received the settlement and are reviewing it.

A cleaner harbor

The Army Corps dredges more than 100,000 cubic yards of silt and sand from the harbor every year to keep it open for navigation.

Last summer, with permission from the MPCA, it began depositing some of that material on the lake side of Minnesota Point. Both the MPCA and the Army Corps say they are certain the dredge material they are using for the project is safe. It was tested before, during and after it was placed.

A lot has changed in the harbor since 1976, said Melissa Bosman, project manager for the Army Corps.

After the Clean Water Act was passed, the harbor and the St. Louis River, which feeds it, truly began to recover from a century of industrial pollution, she said.

Army Corps tests over the past decade show that about 95% of the dredged material the agency now pulls up from the harbor is clean. The 5% that still has elevated levels of mercury, lead, dioxins, or signs of oils, greases or any other pollutant is taken to a land facility and stored, Bosman said.

The EPA and the MPCA set the safety standards that the Corps' fill has to meet to be put on a shoreline or a public beach. Dioxins, for example, which are one of the harmful pollutants that sparked the original lawsuit, are not allowed to exceed 7.2 parts per billion.

The fill used on Minnesota Point tested at .05 parts per billion, Bosman said.

"So that's 100 times lower than the most conservative screening value," she said.

Minnesota Point residents have said the need for the dredge fill is urgent, as rising water has caused erosion and property damage for many of the 300 homes, hotels and businesses on the skinny strip of land.

This spring the MPCA conducted its own tests on the sediment placed a year ago, to see how the beach was holding up and found no elevated levels of pollutants, said Anna Hotz, supervisor of the MPCA's rules unit.

"It didn't exceed background levels," Hotz said. "The act of dredging is closely monitored, and then the placement is closely monitored. We're making sure we get the full picture to truly make an assessment of any risk."