Fortunately, cities such as Philadelphia have quietly begun to solve this problem in a way that could transform urban landscapes from coast to coast. In fact, the City of Brotherly Love is at the forefront of a national trend toward embracing urban design strategies, called "green infrastructure," that can slash water pollution, provide flood protection, beautify communities, and cut infrastructure and energy costs.
Now the federal government needs to catch up. Updates to the Environmental Protection Agency's 20-year-old standards for dealing with runoff pollution are overdue. The agency should move quickly to improve the standards and seize the opportunity to share the benefits of green infrastructure with communities nationwide.
Natural filters
The conventional way of dealing with polluted runoff has been to try to clean the mess up after it's been created by, for example, constructing treatment plants, concrete pipes, canals, and drains. This can help, but it typically deals with runoff pollution at the end of the pipe. And it often allows pollution to flow across streets and sometimes into local waters before it gets cleaned up.
Green infrastructure is more effective, because it stops the problem before it starts. Green roofs, street trees, rain gardens, and permeable pavement capture rain where it falls, preventing it from accumulating pollution and overloading sewage systems. Such features make the urban landscape function more like the natural environment.
