Five years ago this month, Philadelphia embarked on a comprehensive, innovative program that established the city as a national leader in environmental protection, storm-water management, and infrastructure improvements.

Green City, Clean Waters is the city's 25-year plan to reduce storm-water pollution and protect our waterways by using primarily environmentally friendly infrastructure to mitigate problems related to runoff.

In cities like Philadelphia, with vast areas of paved and impermeable surfaces, this is a huge problem. When a heavy rainstorm hits, water pours into the sewers, bringing along spilled motor oil, gasoline, and other surface pollutants. In areas with "combined sewers," these pollutants mix with sewage from homes and businesses and travel through one pipe. When pipe capacity is exceeded, pollution overflows into creeks and rivers.

The primary goal of Green City, Clean Waters is to reduce that pollution by reducing the overflow.

Working with public and private partners, Philadelphia has added more than a thousand green features - such as storm-water tree planters, rain barrels, porous paving, rain gardens, and green roofs - to our neighborhoods to reduce runoff volume and filter pollutants before they enter sewers. In turn, all of this helps protect our rivers and streams.

Working with an array of partners, including community leaders, city agencies, the School District, private developers, elected officials, and environmental advocates, the Water Department is now taking Green City, Clean Waters from its initial phase to a full-scale program. We have greatly benefited from five years of partnerships, planning, evolving designs, construction and maintenance achievements, and a growing knowledge base that is making our rivers cleaner and improving neighborhoods, block by block.

During the first five years, we exceeded regulatory obligations, surpassing our initial goal to achieve 744 greened acres (with reduced impervious cover) and cut 600 million gallons of combined sewer overflow by June 1. I'm proud to announce that we have actually reduced combined sewer overflows by 1.5 billion gallons. Further, as part of our pledge to make our rivers and streams fishable, swimmable, accessible, and beautiful, we have removed 6,000 tons of trash and debris from them.

In all, Philadelphia Water and its partners have completed 141 public green storm-water infrastructure projects. This includes 111 street projects redesigned to capture storm-water runoff with tree trenches, bump-outs, planters, and porous pavement. Eighteen park and open-space projects visibly demonstrate how better storm-water management means more vibrant, engaging recreation areas. Eleven schools now incorporate rain gardens and other techniques to manage storm water - and provide a real-life forum to educate students and residents. Private and incentivized projects have added hundreds of more green sites and manage hundreds of millions of gallons of storm water.

Cultural and economic benefits are also materializing. Neighborhoods are experiencing a renewed enthusiasm for improved streetscapes, new trees, less vandalism and trash, and a higher level of public engagement as these projects improve blocks and public spaces. In addition, Green City, Clean Waters is fueling a green-jobs economy, attracting more innovative and environmentally conscious companies. The program has been cited and celebrated nationally in a wide range of publications.

In short, we've accomplished much in five years. And the next five will be even more challenging. By 2021, our 10-year milestone, the Water Department must achieve 2,148 greened acres - nearly three times what the city has accomplished so far, and enough to keep two billion gallons of polluted water out of our rivers annually.

As we continue to expand this revolutionary program for protecting and improving Philadelphia's most important natural resources - the Delaware River and the Schuylkill, which provide all of our drinking water - we look forward to working closely with our customers, community members, elected officials, partners, and stakeholders in securing a safe and healthy future for generations to come.

Debra McCarty is commissioner of the Philadelphia Water Department.