Oct. 22--SAGINAW, Mich. -- Every spring, Dow Chemical sponsors a fishing tournament "celebrating all things walleye" on the wide, fast-moving river that flows past its sprawling world headquarters.

Signs warn anglers not to eat the fish, which are contaminated with high levels of cancer-causing dioxins the chemical giant dumped into the Tittabawassee River for most of the last century. Yet tournament organizers sell hats featuring the slogan "Dioxins My Ass."

Such conflicting messages are common in this picturesque and economically distressed region, where Dow is a major employer but also responsible for poisoning a river valley that stretches more than 50 miles into Saginaw Bay and Lake Huron.

Now, after three decades of promises by federal and state officials to force Dow to clean up the mess, the Obama administration is stepping in with a new plan intended to scour away decades of contamination that turned this area into one of the nation's most polluted sites.

Late last week, the U.S. Environmental Protection Agency and Dow announced a deal they contend will finally address dioxin contamination from the company's chemical complex in nearby Midland, a company town about 200 miles northeast of Chicago.

The success -- or failure -- of what happens here could affect dozens of other polluted sites along the Great Lakes. Saginaw Bay is one of 31 "areas of concern" on the U.S. side of the lakes that wash toxic chemicals into the world's largest source of fresh surface water. Sites in the Chicago area include Waukegan Harbor, the Grand Calumet River and the Indiana Harbor and Ship Canal.

Under provisions in the federal Superfund law, Dow will be required to evaluate and clean up dioxin-contaminated parks and yards along the Tittabawassee and Saginaw rivers starting this winter. Dow also agreed to work downstream from its plant to remove or cap dioxin-contaminated sediment, preventing toxic muck from repeatedly churning back into the water and from spreading farther into Saginaw Bay. The goal is to restore the entire watershed by 2018.

"We are on the right track now," said Robert Sussman, senior policy adviser to EPA Administrator Lisa Jackson. "Once the work begins, we will have the momentum to get this done."

Given the sluggish pace of previous cleanup work, the EPA's inspector general recently concluded the sites would not be restored until 2086. The Obama administration has promised to set aside more money to speed up things and is pushing to restore a tax on polluters to help cover the tab, estimated to reach $4.5 billion.

Cleanup of the region surrounding Dow's plant has dragged through several administrations. Soon after taking office, Jackson dispatched Sussman to meet with company officials and citizen groups and renewed negotiations that had stalled during the waning months of the Bush administration.

"I agree with community members who believe that this contamination is a threat to public health in the communities in the area, to the vibrancy and diversity of the ecosystem, and to economic development in Northeastern Michigan," Jackson wrote in a May letter outlining the agency's agenda.