By David S. Beckman

Nearly every time it rains, water pollution problems follow. That's because the impenetrable surfaces of our cityscapes - buildings, sidewalks, roads - repel rainwater directly into storm drains and, ultimately, our waterways. Along the way, the water collects a toxic soup of oil, chemicals, animal waste, and trash.

In many parts of the country, this polluted torrent overloads sewage treatment facilities, causing them to overflow and make matters worse. An estimated 10 trillion gallons of dirty runoff ends up in our rivers, lakes, and oceans annually, making storm water one of the nation's greatest sources of water pollution.

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.

Just using permeable pavement instead of conventional asphalt or concrete can make a significant difference. Philadelphia recently installed its first block-long permeable street, and the city's water commissioner said workers "couldn't find any water there" after Hurricanes Irene and Lee pounded the East Coast last fall, despite major flooding elsewhere in the city.

More green spaces also make neighborhoods more appealing and increase property values. They break up urban landscapes with natural beauty and act as filters, lowering temperatures, cleaning the air, and reducing rates of respiratory illness.

Catching on

Concrete tunnels and drains simply don't deliver such benefits. An analysis commissioned by Philadelphia officials compared green infrastructure with a traditional 30-foot-wide tunnel and found that the former would add more than 100 million days of outdoor recreation. City officials believe green infrastructure would even prevent some people from dying of heat-related illnesses.

Green infrastructure is also cheaper. Philadelphia estimated that reducing storm water with traditional approaches would have cost billions of dollars more than the city's 25-year green infrastructure program. Other studies have confirmed these findings. The EPA's own analysis shows green infrastructure usually saves money for developers and communities.

It should come as no surprise that tackling a major pollution problem in a cost-effective way that yields a range of community benefits is appealing to cities across the nation. Like Philadelphia, New York is rapidly developing what may become one of the country's most extensive programs of public investment in green infrastructure. Washington has plans to reduce storm water runoff from 18 million square feet of hard surfaces over the next five years. And Chicago has nearly 500 green roofs and a program to make alleys green, too.

These successes should inspire the EPA to make green infrastructure the centerpiece of new runoff standards that are expected later this year. By updating its standards to reflect everything we have learned about reducing pollution while enhancing neighborhoods and cutting costs, the agency can ensure that the cost-effective, sustainable approaches adopted by Philadelphia become the norm nationwide. And by making our communities greener, we will make our waters bluer.