Urban Land Institute

Green City, Clean Waters

Philadelphia, Pennsylvania

Philadelphia’s Green City, Clean Waters plan has been lauded for its pioneering approach to using sustainable landscaping and green technologies to collectively retrofit its over-100-year-old stormwater and sewage system at a neighborhood scale and at a low incremental cost. The plan features many of the policy tools profiled in this report, promoting green infrastructure at the citywide level and actively involving the private sector.


Green City, Clean Waters represents a holistic approach to incorporating green infrastructure across the city at a cost affordable to taxpayers. Mami Hara, former deputy commissioner of the Philadelphia Water Department, who initially pioneered the project with design firm WRT, explains that the plan did not emerge “with a wide-eyed perspective that we should use this stuff to make things pretty. It’s really from a perspective of trying to make the very best use of all of our investments. In certain places, green infrastructure is the best value, and I think that holds true for developers as well.”

In the 1990s, the evaporation of the federal Construction Grants Program and the threat of lawsuits over contaminated stormwater runoff spurred the Philadelphia Water Department to completely overhaul the city’s aging network of underground pipes, pumps, and treatment facilities. In 2012, Philadelphia reached a consent agreement with the U.S. EPA to finalize a series of decentralized investments over a period of 25 years. These investments and the related policies are outlined in Green City, Clean Waters.

Green City, Clean Waters is estimated to cost $1.6 billion over the lifetime of the project. An independent economic analysis of this plan estimates that, without the Green City, Clean Waters program, the city of Philadelphia would have needed $8 billion to $10 billion and several decades to upgrade and expand its conventional combined sewer overflow system.

Today, the Philadelphia Water Department displays the progress of its stormwater management strategies, spanning 45 percent of city land, on an online interactive map, which includes 409 privately constructed and 474 publicly constructed features to date.

Currently, the following projects are under design or construction:
• 742 stormwater tree trenches;
• 195 stormwater planters;
• 49 stormwater bump outs;
• 179 rain gardens;
• 6 stormwater basins;
• 268 infiltration/storage trenches;
• 63 porous paving projects;
• 48 bioswales;
• 2 stormwater wetlands;
• 33 downspout planters; and
• 25 other projects.

Environmental Benefits

The Philadelphia Water Department is tracking environmental outcomes of its stormwater management services, particularly as they relate to air quality, soil erosion, the cost avoidance of sick days, and health care costs associated with asthma and heart attacks.vi
A 2011 report estimated Philadelphia waterways will have up to 85 percent fewer pollutants and 1.5 billion pounds of avoided or sequestered greenhouse gases through the plants and trees distributed throughout the city. The program has also catalyzed up to $8.5 million in investments over the next 40 years to restore habitats and support biodiversity in targeted locations, including the preservation of 45 acres of existing wetlands, the creation of 148 acres of new wetlands, and the restoration of 7.7 miles of streams in the Cobbs Creek watershed and 3.4 miles of streams in the Tookany/Tacony Frankford watershed.

Economic Benefits

Conservatively, Philadelphia’s sustainable stormwater practices are estimated to have a nearly $60 million economic impact, sustaining 430 local jobs and generating $1 million in local tax revenue. Local firms in the fields of architecture, engineering, and landscaping have been able to export their innovative stormwater management technologies and services to other cities, such as Washington, D.C., and New York City, which seek to emulate Philadelphia’s model policies. From 2013 to 2014, public and private firms related to stormwater management grew 14 percent, with revenues totaling more than $146 million.

Social Equity Benefits

Philadelphia’s Green City, Clean Waters program has concentrated the majority of public and private stormwater management amenities and services in low-income communities to improve environmental and physical health. The stormwater management programs completed in the first five years of the program alone are estimated to have resulted in a total of $9.9 million invested in local schools and $8.1 million invested in city services through property tax revenue.



Philadelphia Water Department, Green City, Clean Waters: The City of Philadelphia’s Program for Combined Sewer Overflow Control, Program Summary, Amended (Philadelphia, 2011), www.phillywatersheds.org/doc/GCCW_ AmendedJune2011_LOWRES-web.pdf.
Sarah Madden, “Choosing Green over Gray: Philadelphia’s Innovative Stormwater Infrastructure Plan” (master’s thesis, Massachusetts Institute of Technology, 2010), 24, http://web.mit.edu/cron/Backup/project/urban-sustainability/Stormwater_Sarah%20Madden/sarahmadden_thesis_MIT.pdf.
Philadelphia Water, Green City, Clean Waters.
Econsult Solutions, The Economic Impact of Green City, Clean Waters: The First Five Years (Philadelphia: Sustainable Business Network of Greater Philadelphia, 2016), www.sbnphiladelphia.org/images/uploads/Green%20City,%20Clean%20 Waters-The%20First%20Five%20Years(1).pdf.
Philadelphia Water, Green Stormwater Infrastructure Project Map, www.phillywatersheds.org/BigGreenMap.