In 1989, the Conservation Law Foundation took aim at combined sewer overflows, which are basically pressure valves that allow raw sewage to drain into rivers and bays whenever rainfall floods sewer systems.

The group released a report and joined a federal lawsuit against major sources of the pollution, including the cities of Portland and South Portland. Nearly 20 years later, Maine communities have spent about $300 million, and counting, to reduce the overflows and clean the state’s waters.

Now CLF is taking aim at another source of pollution that it feels has been overlooked for too long: storm water.

The group is pressuring the state and federal environmental agencies to crack down on businesses with big rooftops and parking lots, but no plans for keeping industrial chemicals and other pollutants out of storm runoff and the environment.

It filed a federal petition Friday calling on the U.S. Environmental Protection Agency to require pollution permits from the businesses in the Maine Mall area, the state’s most prominent collection of impervious surfaces.

Runoff from the roofs and parking lots in the commercial district are polluting Long Creek, which runs into Clark’s Pond and, eventually, Casco Bay.

If successful, the group could help drive new clean water regulation, and a lot of spending, statewide. It wouldn’t be the first time.

Look here for CLF's announcement and petition.