After four years of study and $4 million, the favored route for a tri-county parkway -- a proposed highway that would connect Prince William, Loudoun and Fairfax counties -- is unlikely to get the federal funding or the approval it needs to be built as it is currently proposed, said Ken Wilkinson, project manager for the Virginia Department of Transportation study.

Wilkinson said that the U.S. Army Corps of Engineers looks for roadways that cause the least disturbance to the environment, and that the route favored by 40 percent of the public -- as determined through e-mails, letters and surveys -- is not the best of four proposals.

Wilkinson explained the corps' conclusions at a meeting of the Prince William Board of County Supervisors on Tuesday. Supervisors expressed frustration that the route the public wants and that all three counties already have in land-use plans is no longer an option.

The route is known as the Comprehensive Plan Alternative because all three counties have placed similar routes in their separate land-use plans. It is also the most expensive, at $548 million, and would wind 11.7 miles from Route 50 near Dulles through a bit of Fairfax County in Bull Run Regional Park and east of the Manassas National Battlefield Park, ending at the Route 234 bypass and Route 28 interchange in Prince William County.

In a June letter to the Federal Highway Administration, Nicholas L. Konchuba, chief of the Eastern Virginia Regulatory Section of the corps, wrote that building the road would require a permit from the corps because it would "involve impacts to waters of the United States, including wetlands."

Because the path's potential impact on wetlands and streams is greater than the other routes', the corps would likely not issue a permit for construction, Konchuba concluded in the letter, of which supervisors received a copy.

"This damn thing was on our comp plan for 30, 40 years," board Chairman Sean T. Connaughton (R) said after Wilkinson's presentation, adding that the proposal is now off the table.

Wilkinson said there might be hope, noting that Route 288 around Richmond had similar obstacles but was constructed.

"Mr. Wilkinson, I appreciate you being here. I don't appreciate the message," Connaughton said.

Wilkinson said he will give the same presentation to Fairfax officials this week.

The supervisors also heard a presentation on the Manassas National Battlefield Park bypass study from Jack Van Dop of the Federal Highway Administration. He presented six options for a road that would close some parts of Routes 29 and 234, which currently go through the Civil War park.

When Van Dop said 24 percent of the public favors Alternative G, a $322 million, 10-mile route that wraps around the park's southern end, supervisors questioned the survey. Just 46 people were part of the survey, although Van Dop said the FHA had 3,000 people on an e-mail list.

"There are more people sitting in here now than actually indicated a preferred route," Connaughton said.

Stewart Schwartz -- executive director for the Coalition for Smarter Growth, which has staged several protests against the multimillion-dollar roads -- did not attend Tuesday's meeting. "They are wasting our tax dollars by studying and pushing these bypasses," he said.

The best alternative is to focus on creating interchanges at Route 28 and Interstate 66 that could help alleviate traffic, he said.