Arlington County Manager Barbara Donnellan unveiled a $1 billion budget proposal Wednesday that would raise local real estate taxes and cut spending in every county agency to fend off a $22 million funding gap.

The county's top administrator recommended a 3.2 cent real estate tax hike that would raise the tax rate to $1.003, the first time in more than a decade that Arlington's residential tax rate topped $1.

Donnellan said the increase was needed to accommodate the school system's growing population - expected to increase by more than 1,000 students next year - and to combat costs associated with the construction and staffing of new county facilities.

And with costs rising, the county has seen its commercial tax revenue fall flat, she said, another reason why it's necessary to raise the county's real estate tax.

"Tax base growth in the near-term could remain flat, particularly in the commercial sector, but we see positive signs in the residential market," she said. "We have a strong track record of managing through difficult situations."

Donnellan recommended cutting a combined $9.3 million from county agencies, ranging from condensing the number of county police districts from three to two to reducing employment services for mentally ill adults and the hours of restrooms in county parks.

She proposed eliminating 46 of the county's 3,600 workers. Twenty of the 46 positions are currently filled, Donnellan said, and 20 others have accepted an early retirement package.

"Only a few programs have been eliminated," Donnellan said of her proposed budget. "The existing workforce will absorb much of the workload."

The county manager's presentation to the County Board Wednesday was the first in a series of planned meetings. The board will vote on the budget April 20.

Board Chairman Walter Tejada said the proposed budget was "a good frame of the challenge we're facing locally," but cautioned against getting too comfortable with proposal with sequestration looming.

"It seems we have to be very guarded these days," Tejada said. "The potential that thousands of federal employees are being adversely affected is a reality."

Board member Libby Garvey said she also was concerned with the unknowns associated with sequestration.

"This feels to me like one of the most uncertain times we've been in," Garvey said.

Donnellan will formally present her proposed fiscal 2014 budget to the public and County Board on Saturday.