The Interior Department has recommended against routing the proposed Springfield bypass through two Fairfax County parks, winning praise from environmentalists but dealing a setback to officials trying to reduce the highway's impact on nearby communities.

In a letter mailed Friday, the department recommended against building the road through Popes Head Park and Burke Lake Park. Federal environmental law prevents the taking of parkland for highways unless there is "no reasonable and prudent alternative."

The letter said the taking of more than 10 acres of parkland for the highway would not be justified because the impact of the road on adjacent neighborhoods does not "constitute a unique problem, an unusual factor or a community disruption of extraordinary magnitude."

The proposed highway would cross Fairfax County for 33 miles between Rte. 7 in the northwest and Rte. 1 in the southeast. Construction is scheduled to begin on some segments next year.

The letter was directed to the Federal Highway Administration, which will make the final decision on whether the road can be routed through the parks. A copy of the letter was obtained by The Washington Post.

"We're not bound to follow it, but they are a commenting agency and we certainly have to look very carefully at their comments," said Robert Gatz, director of the planning office for the FHA's regional office in Baltimore.

A ruling against the plan to build through the parks probably would not delay the project. Because the federal government rarely grants permission to build highways through parks, the Virginia Department of Transportation designed the road with alternative paths, one that crosses parkland and one that does not.

Nevertheless, Fairfax County officials had promised residents along the path of the highway that they would try to secure permission to build through the parks.

"What it does is increase the impact on some of the citizens adjacent" to the parks, Fairfax County Board Chairman John F. Herrity said yesterday.

Paul Geithner, a resident of the Colchester Meadow subdivision adjacent to Popes Head Park, called that park a "landfill" with little recreational value, noting that the acreage once served as a Nike missile site. "It looks no more like a park than a city dump," he said.

Geithner said that if the road is built to avoid the park, "there will be a four-lane divided highway 100 feet from my house. It would almost be better if they took my house."

Geithner said he and other residents bought their houses based on the county master plan, which called for building the road through Popes Head Park.

Environmentalists praised the recommendations. "That certainly is consistent with the stand we took," said Gary Nelson, transportation chairman of the Northern Virginia Conservation Council. He said building the road through the parks would create excess storm water runoff and a noisy intrusion into tranquil wildlife areas.

Popes Head Park, with nearly 100 acres, serves as a refuge for deer, fox and other animals, Nelson said. "It's a very significant conservation area."

The highway project would consume 8.2 acres in Popes Head Park and 2.5 acres in Burke Lake Park.

The state and county also are seeking permission to build the bypass through two other parks, South Run Park and Huntsman Park, options that the Interior Department found less objectionable than the others.

The department found that impacts on Huntsman Park would be "minimal" because the road would consume less than 0.01 of an acre. While the road would consume about 6.5 acres of South Run Park, the department suggested that was better than the alternative, which would involve moving 50 to 60 graves in the Lee Chapel Cemetery.