Allowing polluters to buy, sell or trade water-quality credits could significantly reduce pollution in river basins and estuaries faster and at a lower cost than requiring facilities to meet compliance costs on their own, a new Duke University led study finds. The scale and type of the trading programs, though critical, may matter less than just getting them started. The analysis in the journal Water Resources Research shows that water-quality trading of any kind can significantly lower the costs of achieving Clean Water Act goals.