The Seattle City Council voted unanimously this afternoon to ban single-use shopping bags, in what City Hall is casting as an effort to protect marine wildlife. That will eliminate 292 million bags a year, of which, only about 13 percent are recycled while other bits of plastic end up floating in Puget Sound, according to Seattle Public Utilities.

The question is: Will the ban stick? City law provides a 30-day window for someone to file a referendum and begin gathering approximately 16,000 signatures to place the measure on the ballot. That's what happened in 2009 when the American Chemistry Council (ACC) spent a record $1.4 million on a successful city campaign to overturn a 20-cent fee on paper and plastic bags.

The plastic lobby still has money to spare on this issue. Bag maker Hilex Poly bought a half-page ad on Friday in the Seattle Times that promotes recycling and condemns bans and fees (here's the ad). Along with the ACC, Hilex Poly and other bag makers could fund another campaign.

But Council Member Mike O'Brien, who sponsored the bill, hopes his ordinance is bulletproof. As templates, he used bills that passed in Bellingham and Mukilteo this year that, for now, are still around. In addition to banning disposable plastic sacks, Seattle law requires grocers to collect a five-cent fee for paper bags that the grocery store keeps. As I reported earlier this month, that provision won the support of the Northwest Grocery Association—which represents the largest grocery chains in Seattle, including Safeway, QFC, and Fred Meyer. If Seattle's bag ordinance is challenged with a ballot referendum, Northwest Grocery Association president Joe Gilliam says, "It's possible that we would contribute to the campaign to uphold the law."