A plan to raise millions for the Chesapeake Bay cleanup would charge Maryland developers for paving over dirt.

A proposal announced in February would start a “Green Fund” charge on new development in Maryland to pay for efforts to reduce nitrogen and other pollution in the Bay. Supporters say the fund could raise $130 million a year to speed cleanup efforts with the aim of getting closer to the 2010 goals of improving water quality in the Bay.

Here’s how it would work: Builders would pay 25 cents a square foot for any surface that water can’t get through, such as a traditional roof, parking lot or driveway. The fee would go up eight times—to $2 a square foot—if the new construction occurred outside an area designated for growth.

The fee could add $6,000 to a house built on a quarter-acre lot outside a growth zone, said Kim Coble, Maryland director of the nonprofit Chesapeake Bay Foundation, which promoted the “Green Fund” idea.

“This bill will be benefiting all of us,” Coble said.

The fee could be reduced by up to 25 percent through the implementation of actions that reduce runoff from the site.

If builders pass on the fees to home buyers, the increase in the cost of a mortgage on an average house on a quarter-acre lot would be $5 per month inside a growth area and $38 per month elsewhere, Coble said.

According to the CBF, the fund—coupled with existing programs—would achieve 75–85 percent of the state’s pollution reduction commitments.

The biggest chunk of the money—35 percent—would go to the state Department of Agriculture, and be earmarked for environment-friendly programs such as one that pays farmers to plant winter cover crops to reduce pollution.

Other portions would go to the state Department of Planning, to help local governments plan for growth; the Department of the Environment to help local stormwater and sewer planning efforts; the Department of Natural Resources to support stream buffer, wetland and oyster restorations; the Department of Housing and Community Development to promote housing in designated growth areas; the Chesapeake Bay Trust to provide grants for innovative agricultural and stormwater programs; and the University of Maryland and various agencies to provide technical support for cleanup efforts.

Additions to existing homes would be exempt, and developers could reduce the fees by taking environment-friendly construction steps such as building a “green roof” covered in plants.

Developers did not attend the announcement. Tom Ballentine, policy director for Home Builders Association of Maryland, said his group hadn’t taken a stance on the bill but that it appeared uneven.

“It looks to me this is going to ask new homeowners to pay more than their fair share to pay to clean up sediment pollution from farms,” Ballentine said. He added, “Cleaning up the Bay is supposed to be something we all pay for.”

Del. Maggie McIntosh, chairwoman of the Environmental Matters Committee and a backer of the bill, said that development is threatening Bay cleanup efforts, especially in rural areas.

“It’s smart growth with some teeth in it,” McIntosh, D-Baltimore City, said of the fee. “Development is the last threat to the Chesapeake Bay. It doesn’t have to be.”

Senate President Thomas V. Mike Miller, asked for his position, called the bill “laudable” and “very important.” and said he supports “finding funds to clean up the Bay.” But Miller said he’s not sure whether the General Assembly will pass the legislation, given that the state needs to raise money to deal with a projected deficit in future years.

Roger Richardson, designee to be the agriculture secretary under Gov. Martin O’Malley, praised the idea to raise money for better farming practices. “Farmers really are your first environmentalists,” Richardson said.