In the on-again, off-again saga of the Waldorf bypass, state transportation officials warned the Charles County commissioners this week that rapid development in the area could jeopardize the long-debated alternate route around one of Southern Maryland's most congested traffic corridors.

"If the county continues to allow development to occur on both the western and eastern bypass corridors, it puts this project at risk," State Highway Administrator Neil J. Pedersen wrote in a letter to county leaders.

Failing to protect the potential routes, Pederson wrote, could "make it impossible for the state to deliver these needed transportation improvements."

State Highway Administration officials urged the county commissioners Tuesday to try to stall development along several possible paths, or alignments, for the bypass while the state conducts environmental studies required under federal law. That would require broader planning powers and changes to the county policy.

If the county follows through on the state recommendation, it is likely to prompt opposition from local property owners and developers. David Cooksey of the engineering and planning company Loiederman Soltesz Associates in Waldorf said expanding the county's powers would "pretty much stop development across the whole county."

"There are not that many places left,'' said Cooksey, who has a half-dozen projects that would be affected by such a change. "It would have a significant impact."

Finding a way to divert non-local traffic around the congested commercial shopping and service district along Route 301 has been the topic of discussion and planning for at least 15 years. Local leaders have debated whether to bypass Waldorf to the east or west and how to avoid damaging wetlands.

An unanticipated increase in state transportation funding last year revived plans, and commissioners and state officials agreed Tuesday that the Waldorf bypass is critical because of the county's continued growth.

The highway administration is "pursuing this project as a priority," Raja Veeramachaneni, the director of the office of planning, told commissioners at their weekly meeting in the County Government Building in La Plata.

The problem, he said, is that development threatens to limit the options engineers have to pave a path around the congested area in Waldorf. Veeramachaneni's office has identified pieces of four properties scheduled for development that he said should be bought or reserved within the next six months to avoid delays or insurmountable costs. Purchasing the land would cost about $42 million, according to the state's estimates.

To comply with the state's request, the county would have to tweak a policy adopted two years ago that allows it to reserve land for public projects in exchange for a tax exemption for the landowner. As written, the law allows the county to put pieces of private property off-limits to development for three years, but just along one route identified by the commissioners.

The county, for instance, reserved a slice of the turf farm on Berry Road that could become a business park. But that agreement has expired.

The state wants the county to change the policy to make it possible to reserve land in several locations at once, in this case so the state can study several alignments to comply with environmental regulations.

The most recent map of possible bypass alignments from January 2002 has numerous potential routes that one planning official compared to strands of spaghetti.

Commissioner Candice Quinn Kelly (R-La Plata) said she was "extremely concerned" by the state's assessment. "We need this to move forward," she said.

County attorneys are in discussions with the state attorney general's office about how to proceed.

If the state can move ahead, Veeramachaneni said, the first formal public hearing on a study could come in late 2007.

Commissioners President Wayne Cooper (D-At Large) asked for a time frame for the project. The last estimate said it would take 15 years to complete a bypass from the time of approval. Veeramachaneni reminded the commissioners that the planned intercounty connector from Gaithersburg to Laurel has been on the books since the 1950s.

Cooper responded: "Give us a little more hope than that. We really need it."