PCBs have trickled into Lake Michigan from the Kinnickinnic River for decades, but a $22 million project now is under way to stem the flow of industrial pollutants into the lake.

The cleanup is the first step for potentially tens of millions in additional dollars to restore the natural character of Milwaukee's forgotten river.

The project is intended to remove harmful polychlorinated biphenyls from the troubled Kinnickinnic between W. Becher St. and S. Kinnickinnic Ave.

It began last month, with crews working up to 24 hours a day deepening the river and removing pollutants from the 2,000-foot section east of I-94.

This year, the state Department of Natural Resources and the U.S. Environmental Protection Agency anticipate the removal of 170,000 cubic yards of contaminated sediment, including 1,200 pounds of PCBs and 13,000 pounds of polyaromatic hydrocarbons, a petroleum byproduct.

In 2007, American Rivers magazine called the Kinnickinnic one of the 10 most troubled rivers in the nation.

Vast stretches upstream are lined with concrete and are bereft of natural habitat and prone to flooding. Excessively high levels of road salt taint the river during the winter, according to a 2008 U.S. Geological Survey study.

"When I first started working here seven years ago, people said, 'Forget the KK; it's long gone,' " said Cheryl Nenn, interim executive director of Milwaukee Riverkeeper.