The Indian Head Division of the Naval Surface Warfare Center plans to ask the Navy for authorization to lay off about 100 workers, according to base officials.

Such a layoff would likely be the largest in recent years at the Navy installation, the biggest employer in Charles County.

In addition, 40 workers at the division have accepted offers by the Navy to leave their jobs. They will be off the payroll by Sept. 30, according to Chris Adams, a spokeswoman for the division. They are part of a group of 100 workers who were offered separation incentives, Adams said.

The reductions are necessary to get the Indian Head work force in balance with a decreasing workload, officials said.

"Downsizing at the Indian Head division is consistent with and responsive to projected . . . Navy budgets," Mary Lacey, the director of the Indian Head division, said Tuesday.

In addition, six division workers are already in the process of being laid off as the result of conclusions reached in a separate commercial activities study of supply and inventory management operations at Indian Head. Workers at Indian Head perform some work for private businesses who contract with the Navy.

The proposed layoff of 100 workers would have to be approved by the Navy, followed by notification of Congress. Implementing the reduction would take a number of months. The positions that would be eliminated have not been selected, according to Adams.

"We're in the process of evaluating our workload right now and identifying what positions would be affected," Adams said. The layoffs would likely not be concentrated in any particular section or type of work. "There's no one pocket," Adams said.

"A [reduction in force] is always an unfortunate last resort option," director Lacey earlier told Business, the newsletter of the Charles County Chamber of Commerce. She said anyone "affected by RIF will . . . be put on a priority placement list for government jobs and will be given offers for vacancies in which they qualify."

The Indian Head division employs 1,822 people, while a total of about 3,000 people work at the century-old installation along the Potomac, which conducts research and development of ordnance for Navy ships.

The latest reductions are part of an ongoing reduction in the work force at the division that has accompanied a general downsizing of U.S. defense spending by Congress. Over the last seven years, the division's work force has been reduced by about 1,000, or more than 30 percent, through attrition, including normal retirements and people accepting early retirement offers.

"As we look at the question of whether the work we have matches the work force, it's always a possibility that we'll ask authorization to conduct a reduction in force," Adams said.

Employees "know why this is happening," Adams added.