After a substantial clean up effort, portions of the Fox River have seen significant decreases in chemical pollution according to a recently released study conducted by the Wisconsin Department of Natural Resources.

Agents from the DNR and U.S. Environmental Protection Agency began a clean up of the Little Lake Butte Des Morts, whose north end becomes the section of the Fox River leading into Green Bay, in 2004.

The project took until 2009, when the DNR began taking water quality samples and tested walleye in the lake for quantities of Polychlorinated biphenyl, a chemical found to cause health problems in people including developmental problems in infants.

Sample results showed a dramatic decline in levels of PCB, according to the study. Gov. Scott Walker and DNR Secretary Cathy Stepps held a press conference along the banks of the Little Lake Butte Des Morts Thursday to express their satisfaction with the results of the cleanup.

“This is a great milestone in the recovery of a river that’s such an important economic engine and natural resource for this region and our state,” Walker said in a statement released after the press conference.

Specifically, the EPA and DNR study found a 73-percent reduction in the amount of PCB within walleyes, Gary Kincaid, a DNR engineer involved in overseeing the project, said.

He added the clean up resulted in far lower levels of PCB concentration in walleye, water and sediment than the DNR and EPA had originally set out to meet.

The PCB levels were lowered through a process called capping, which consists of putting sand, gravel and stone over the sediment that has PCB contaminants.

Kincaid said capping is a permanent and good solution to the problem and will be continually reviewed by an oversight team to make sure the caps are doing their job.

If the system were to fail, it would be fixed or the sediment would be removed promptly, Kincaid said, hoping to assuage the fears of citizens who worry capping is not a successful way to deal with PCB contamination.

The project was funded with $99 million, Kincaid said.

With other segments remaining for cleanup, Kincaid said they would continue to do full scale remediation in all places with considerable PCB contamination.