A metal-plating company in St. Louis Park must eliminate ongoing pollution that’s contaminating Lake Calhoun and its fish within two years or face daily fines.

Last month, Douglas Corp. signed an agreement with the Minnesota Pollution Control Agency (MPCA) to address pollutants in stormwater runoff reaching the lake from a manufacturing facility about a mile away.

The chemicals, known as PFOS, were used by the company as recently as 2010 and had accumulated on the roof, according to the MPCA. Rain and snowmelt then carried the PFOS into the stormwater system, which eventually flowed into the lake. Since being identified as the source of pollution in 2010, the company has been working with the MPCA to get rid of sources of contamination by replacing the roof, roof vents, tanks and other structures.

“They were cooperative,” said Scot Sokola, a water quality compliance coordinator at the MPCA. “We had many meetings with the company and gave them instructions in what we would like to see them do, and they carried them out throughout the process.”

But the contaminants, from a family of man-made chemicals known as perfluorochemicals (PFCs), are still present, albeit in lower quantities.

Douglas Corp. officials said they will continue to address the issue. The company first became aware of PFOS in a product they used in 2007, said John Fudala, vice president of the plating division.

“As soon as we realized that, we sought out and found alternatives that didn’t contain PFOS,” Fudala said, noting they had stopped using the product completely by 2010.

According to the MPCA agreement, the company must decide how to address its contaminated stormwater within six months, either by capturing the runoff before it leaves the facility or by treating it. It must put to use its solution by May 4, 2018. Failure to do so will incur daily fines of $500 per violation, Sokola said.

Near the company’s St. Louis Park facility, shallow groundwater has also been contaminated, but state pollution officials haven’t found any PFOS in surrounding drinking-water supplies. The agreement also calls for the company to investigate the extent of the contamination.

“The document is designed to remedy Calhoun and protect the groundwater,” Sokola said.

Contaminated fish

While most Lake Calhoun visitors would not notice the PFOS contamination, it is present in the lake’s fish and may cause harm if eaten repeatedly over a long period of time.

The chemical was first discovered in Lake Calhoun by a University of Minnesota researcher in 2004.

The Minnesota Department of Health has had an advisory in place since April 2006, cautioning people against eating fish contaminated by PFOS, said Pat McCann, fish advisory program manager at the health department.

With other contaminants, such as mercury, smaller fish have lower amounts of pollutants. But PFOS contamination is trickier.

“Unfortunately, it doesn’t follow that rule,” McCann said. “It’s more difficult to predict which fish would have higher levels.”

Currently, largemouth bass tissue holds the highest levels of PFOS, despite decreasing by more than half since 2008.

Health officials caution against eating more than one meal per month of bass from Lake Calhoun. Other fish types — such as bluegills, crappies and northern pike — also contain elevated levels of the chemical but can be eaten more often.

The health threats posed by PFOS range from liver issues to immune system problems, which have been observed in animal studies, McCann said.

The lake, however, has no advisories against boating or swimming, and the MPCA hopes that contaminant levels will decrease enough for the fish advisories to end.

Minneapolis park officials said the lake is busier than ever and view the recent agreement between the MPCA and the company as a positive step forward.

“It’s been a long process,” said Rachael Crabb, water resources supervisor for the Minneapolis Park and Recreation Board. “We’re just really pleased that they’ve been able to come to an agreement that benefits Lake Calhoun.”