MADISON, Wis. (AP) — Two of Wisconsin’s most polluted sites on the Great Lakes are marking cleanup milestones, after the state Department of Natural Resources declared both waterways to be no longer impaired.

The Lower Menominee River and the St. Louis River are among five areas in the state designated as Areas of Concern and featured on a list of most contaminated sites on the Great Lakes. The department removed impairment designations for the two rivers in February, Wisconsin Public Radio reported.

The Lower Menominee River was listed for arsenic, coal tar, oil and grease pollution. The river originally had six out of 14 types of impairment classifications set by the U.S. Environmental Protection Agency.

The removal of the site’s last remaining impairment for degraded fish and wildlife populations could result in its removal from the Great Lakes contamination list this year. It would become the first site in Wisconsin to be removed from the list, said Kendra Axness, Area of Concern and Lakewide Action and Management Plan policy coordinator with the Wisconsin DNR.

The Great Lakes Restoration Initiative , which was started by former President Barack Obama, has provided about $300 million each year for cleanup work around the Great Lakes since 2010. The initiative has been vital to the restoration effort, Axness said.

“The acceleration of the progress that’s been accomplished by the GLRI is really astounding,” she said. “I hope we get to continue to keep doing this good work because I think we’re making really good progress.”

The impairment against the St. Louis River was removed after scientists confirmed that the health of the river’s fish population had improved, the DNR said.

Scientists conducted studies of the river from 2011 to 2015. Researchers found that less than 5% of the roughly 620 white suckers that were examined had skin or liver tumors, a rate lower than elsewhere in the Great Lakes, said Matt Steiger, St. Louis River AOC coordinator at the DNR.

“The sucker is an important food source for a lot of other game fish that people are out there pursuing,” said Steiger. “If that’s a healthy population, we can hope that’s reciprocated through other sought-after species in the estuary.”