Mayor Nutter fulfilled an important campaign pledge with his appointment last week of Mark Alan Hughes as Philadelphia's first sustainability director.

While the mayor and his administration have made it clear that sustainability is a top priority, a point person to lead and coordinate these efforts is absolutely critical to its success.

Hughes is a senior fellow in the University of Pennsylvania's Fox Leadership Program. His experience in urban-policy development as well as his proven ability to work with a broad spectrum of groups will aid him as he works to put Philadelphia on the national map as a green city.

The Next Great City coalition, which now includes almost 100 organizations, first put sustainability issues on the map during the mayoral race by releasing a commonsense, cost-effective environmental agenda in January 2007.

The following month, the coalition hosted the first issues forum, attended by all of the Democratic candidates. As a result, the 2007 mayoral race was the greenest in Philadelphia history and helped to focus attention on important issues such as energy conservation, air quality, recycling and parks.

Much progress has already been made. Single-stream recycling was expanded again and will be citywide by July. The Zoning Code Commission is meeting and will make recommendations to update the city's outdated rules on land use and development. The budget proposed by Nutter provides funding for parks and trees.

And more than ever, both residents and businesses are seeking ways to be part of the green movement.

But to truly fulfill the mayor's goal of becoming the "greenest city in America," significant work must be done.

Philadelphia still hasn't implemented many of the Next Great City recommendations, such as working to reduce diesel emissions from city trucks, which exacerbate asthma rates; preventing sewage backups and flooding, which cause property damage and public health problems; opening the riverfronts to the public and reconnecting them with bordering neighborhoods; cleaning and greening vacant lots to attract development and stabilize communities; improving transit stops to be safer and more user-friendly; and being smarter about energy use by buying or generating renewable energy and building energy-efficient buildings.

We also must make sure the progress made on recycling, zoning, and parks and trees is the beginning, not the end.

Beyond the Next Great City agenda, there are many existing projects and initiatives that the new sustainability director must take on.

The electrifying and inspiring presentation by California environmental activist Van Jones at the Urban Sustainability Forum in February has sparked the creation of task forces exploring how Philadelphia can grow its green economy and help employ people in sustainable jobs.

Hughes should be looking at ways that Philadelphia's procurement policies, zoning laws and workforce training can help to attract and maintain green businesses.

Many agencies and departments within city government have already begun to look at sustainability, with excellent results.

Green Plan Philadelphia, the city's first comprehensive open-space plan, is scheduled to be released this year. The Local Climate Change Action Plan also was put together through the work of many dedicated city employees.

Hughes must support this work and make sure the recommendations from each of these bodies are fully embraced and implemented.

There is a wealth of experience among Philadelphia's environmental organizations that have already researched what needs to be done, including the Pennsylvania Environmental Council's Building Green report, the Civic Vision for the Central Delaware by Penn Praxis, and the Pennsylvania Horticultural Society's Green City Strategy. These reports and others deserve to be incorporated into city policy.

Under Hughes' leadership, the city should also follow and support grassroots efforts, such as those to bring a public-use bike-sharing program to the city, or those that bring local, sustainable foods into inner-city neighborhoods.

The energy and enthusiasm of activists can and should be used to help move Philadelphia forward.

It's a big job, but with Nutter's support and leadership, Hughes could be just the person to do it.