The Potluck

Minnesota’s Flint Hills refinery is one of the largest polluters of a toxic metal, according to new report

By: - February 6, 2023 1:44 pm

The Marathon oil refinery in St. Paul Park. Photo by Max Nesterak/Minnesota Reformer.

Flint Hills Pine Bend Refinery in Rosemount is one of the largest polluters of a toxic metal called selenium, according to a new report from the Environmental Integrity Project, an organization established by former Environmental Protection Agency regulators.

Selenium is toxic to fish and other aquatic life, causing mutations and reproductive problems. Selenium can also make its way through the food chain and threaten other wildlife, “sometimes decimating populations,” according to the report. 

Selenium is often dumped into fragile waterways that people depend on for fishing and recreation. 

Flint Hills Pine Bend Refinery — which supplies more than 50% of the gas and diesel sold in Minnesota and around 40% of fuel in Wisconsin — released 2,875 pounds of selenium in  2021. It’s the fourth largest polluter of selenium in the United States. 

The report found U.S. refineries released an estimated 60,000 pounds of selenium into waterways in 2021, even though an EPA study in 2019 found that technology can reduce selenium levels in refinery wastewater up to about 80%. 

In an email, a representative from Flint Hills Resources said the Minnesota Pollution Control Agency “has recognized the Pine Bend refinery as an outstanding wastewater treatment operator for the past 14 of the last 17 years.” 

“It is a priority to seek, innovate and find ways to responsibly source water, use less of it, treat it and ultimately return it safely to the environment,” the representative of Flint Hills Resources wrote. “These measures include our use of stormwater, re-use of steam condensation and implementation of reverse osmosis technology to enhance recovery.” 

An MPCA representative said in an email that the agency sets limits for selenium discharge from refineries, and Flint Hills Refinery hasn’t exceeded the threshold. 

The EPA limits the amount of selenium coal power plants can discharge, but the rules don’t apply to refineries, which release even more selenium. Minnesota does set standards for the amount of selenium considered “acceptable” for public use and the MPCA has the authority to enforce those standards, as well as to create “site-specific standards” for specific waterways. 

“The lack of controls over these pollutants from refineries is dangerous and requires EPA action,” the report said. 

Our stories may be republished online or in print under Creative Commons license CC BY-NC-ND 4.0. We ask that you edit only for style or to shorten, provide proper attribution and link to our web site. Please see our republishing guidelines for use of photos and graphics.

Grace Deng
Grace Deng

Grace Deng was a reporting intern with the Minnesota Reformer. They studied legal studies and Asian American Studies at Northwestern University. The Seattle native has previously been a statehouse intern with USA TODAY Network Ohio and an editorial fellow with Washingtonian Magazine.