Pine Bend refinery in Rosemount is a top source of fish-harming element, report says

A Minnesota oil refinery is one of the industry's biggest emitters of a mineral that can harm fish, releasing it in wastewater bound for the Mississippi River, according to a recent report.

The analysis done by the nonprofit watchdog group Environmental Integrity Project points out the Pine Bend refinery in Rosemount as the fourth-biggest source of selenium in wastewater among U.S. oil processors.

The element can accumulate in the bodies of aquatic animals and build up through the food web. Coal-burning power plants are limited in how much selenium they can release into rivers, but not oil refiners, said Eric Schaeffer, executive director of the Environmental Integrity Project.

"Our point was to say, there aren't really up-to-date [pollution limits] at all," he said, "and there aren't requirements that apply to most of your pollutants."

Pine Bend was the only Minnesota facility mentioned of 81 studied in the report. It released 2,874.8 pounds of selenium into the Mississippi River in 2021. It was not cited as a top source of any of the other pollutants highlighted in the report, which included nickel, nitrogen and total dissolved solids.

Jake Reint, the vice president of communications for Pine Bend owner Flint Hills Resources, said the company is operating within the requirements of its water permit. The permit does not have a limit on how much selenium can be emitted, but it does require that the refiner report the amounts to the Minnesota Pollution Control Agency (MPCA).

Selenium naturally occurs in the crude oil that Pine Bend processes into gas, diesel and jet fuel, Reint said. He noted that the other top selenium emitters in the report also process heavy crude, which may contain more of the element. Pine Bend is the 15th-biggest refiner in the country and second-largest in the Midwest, processing 375,000 barrels of oil a day.

Andrea Cournoyer, a spokeswoman for the MPCA, wrote in an email that the agency sets water pollution limits based on how much a plant is releasing and whether that could break a water quality standard in a nearby river like the Mississippi.

"The data review showed that the selenium standard for [Pine Bend] is being achieved," so no limit there was set, Cournoyer wrote.

That data will be reviewed again when Pine Bend has to renew its permit, which expires later this year, she added.

In small doses, selenium is an essential nutrient and is sold in dietary supplements. But too much of the element causes significant problems in fish when they reproduce, said Isaiah Tolo, a fish health supervisor with the Minnesota Department of Natural Resources.

The element can build up as the fish eat smaller animals that also have selenium in their system. In embryos, developing fish may mistakenly incorporate selenium into proteins instead of necessary nutrients, which can compound into bigger problems such as deformities in the spine or gill coverings and misshapen or missing eyes.

"It makes me interested in looking," Tolo said of the report about Pine Bend's emissions. "l'll definitely be putting Spring Lake on my sampling request for this year, to look for selenium in that fish."

The "lake" is really a bend in the Mississippi adjacent to Pine Bend. Tolo said he wasn't aware of any cases where selenium had caused defects in Minnesota fish.

Selenium has not sparked concern locally as an issue in the river before — two local environmental groups focused on clean water were not familiar with it.

Tolo said he wasn't surprised that the pollutant was little known, because it mostly affects fish.

"The thresholds for contaminants are so much lower for aquatic life than they are for humans," he said. "A lot of our programs are really based [on] human health, not around fish or aquatic life health."

There is one waterbody in Minnesota with a special standard for selenium: the lower Minnesota River, between the Seneca Wastewater Treatment Plant in Eagan and the confluence with the Mississippi. The treatment plant handles the water from a local lead battery recycler, another potential source of the element.

Cournoyer wrote that the Seneca plant has also been in compliance with its water permit.