A persistent abandoned-property problem has reduced the value of Philadelphia homes by an average of $8,000, according to a new study.

The report from Econsult Corp. puts Philadelphia's blight troubles into stark economic terms, estimating that the more than 40,000 vacant or abandoned properties rack up $20 million in annual maintenance costs, rob the city of $2 million in annual tax revenues and reduce property values.

"Vacancy is a citywide problem. No neighborhood escapes the problem of vacancy," said Econsult's Richard Voith, who did the study on behalf of the Redevelopment Authority and the Philadelphia Association of Community Development Corporations.

Armed with a new study about an old problem, the Nutter administration is figuring out what to do next. A series of anti-blight programs over the years, including former Mayor John Street's $296 million Neighborhood Transformation Initiative, have not turned things around.

Mayor Nutter has put Managing Director Richard Negrin in charge of a task force charged with analyzing the city's vacant-land management and offering recommendations. Negrin's chief of staff, Brian Abernathy, acknowledged yesterday that initially the task seemed daunting.

"When we first started to take a look at this over the summer, 'overwhelmed' is the way to describe how Rich and everyone felt," Abernathy said.

Abernathy said city officials are working on key questions, like how to manage foreclosures, bundle lots for development and clean up vacant land. He said the city is already working on a master list of city-owned vacant properties, as well as a list of privately held abandoned properties.

"At the very least, we need to make sure there's a seamless entry point" for developers or interested buyers, Abernathy said.

Dealing with blighted land in Philadelphia is a complicated task. Only about 25 percent of the vacant or abandoned land is city-owned, and those properties are divided among several agencies. About half of the privately held properties owe back taxes. Sometimes they go to sheriff's sale, but often they just decay.

Abernathy and other officials said they hadn't zeroed in on a plan for vacant land.

One example that has been heralded is in Genesee County, Mich., home to Flint, where the government set up a land bank that takes control of abandoned and tax-foreclosed properties and decides the best use - be it to sell the property to a developer, to give it to a community group or to maintain the land itself.

But officials yesterday wouldn't commit to putting all the land management under one agency.

"The city needs to figure out what makes sense," said Rick Sauer, executive director of PACDC.

Mayor Street made reducing blight a central goal of his administration. His Neighborhood Transformation Initiative leveraged $296 million in bond money, with plans to tear down crumbling buildings, package cleared lots together and get them to developers.

His administration reduced the number of blighted buildings and encouraged development, but critics noted that it fell far short of his goal to demolish 14,000 buildings and that little was done about the cumbersome process of seizing abandoned properties and getting them on track for development.