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Ludington Daily News, Jeff Kiessel, File) MANDATORY CREDIT, Associated Press
In this photo taken Aug. 10, 2010, an unidentified Pere Marquette Township resident holds waste that has been washing up onto the shoreline near the Buttersville Peninsula beach in Ludington, Mich. The waste contains a variety of items including medical waste, plastic and paper products.

TRAVERSE CITY, Mich. — The Obama administration says it will be more flexible when pushing financially struggling cities to upgrade their sewage systems to prevent overflows that foul U.S. waterways with harmful bacteria and viruses.

The Environmental Protection Agency has reached legal settlements on sewer overflows with more than 40 cities and counties since the late 1990s. Many require improvements costing hundreds of millions of dollars.

The U.S. Conference of Mayors says the price is getting too steep with the economic downturn, which has cut into tax revenues.

EPA officials say they'll allow greater use of cheaper alternatives, including "green infrastructure" such as rain gardens and permeable pavement that reduce the amount of storm water flowing into sewers.