From Seattle to Sweden, an ever-growing number of city and regional governments are using roof gardens, specially designed wetlands, and other forms of “green infrastructure” to rein in pollution from countless diffuse sources — and to save money.
While large cities such as Seattle, Milwaukee and Philadelphia have adopted rain gardens, green roofs, and other aspects of green infrastructure, it’s still a young field and much about the approach is untested and evolving. “This is really technology on the move,” says Weinstein. “Five years ago there weren’t any green roofs. Now they are all over the place.”