The Prince William County Board of Supervisors raised building permit and rezoning fees by an average of 50 percent yesterday in an effort to raise county revenues to meet the budget passed this spring.

The newly approved fees, effective Friday, are expected to increase county revenue by $570,000, said Finance Manager Connie Bawcum. The board also directed that another group of fees--for public assembly permits, taxicab licenses and blasting permits, among others--be increased to raise another $60,000. A public hearing on thoses increases will be held next week.

Bawcum said that while building permit and rezoning fees can be raised without a public hearing, other proposed fee increases require a change in the County Code and come before a public hearing before supervisors can vote.

In May, the Fairfax County Board of Supervisors approved a 38 percent increase in builders' fees which they said will now cover 65 percent of the cost of running the county Department of Environmental Management, which reviews building plans. The board will hold a public hearing later this year to consider raising the fees to cover 100 percent of the costs.

The Fairfax supervisors said before the vote that they wanted contractors to shoulder more of the county's costs for reviewing construction plans and inspecting new homes, a sentiment echoed by Prince William supervisors.

The building permit and rezoning fees approved by the Prince William supervisors yesterday will cover 75 percent of county costs, according to the new fee schedule released by the Department of Development Administration, which issues building permits and inspects building sites.

In Prince William, the supervisors said they intended to raise user fees when they passed the county's $106.5 million budget earlier this year. The budget took effect July 1.

Bawcum said not all fees will be raised at the same rate, and some are not being raised at all. For instance, the cost of motor vehicle registration will remain the same while the cost of a taxicab permit would jump from $50 to $125 under the proposed fee schedule.

Under the new fee schedule approved yesterday, a developer applying for a building permit in an area zoned for town houses will pay the county $1,100 plus $50 for every acre, compared with the current rate of $460 plus $20 an acre.

To apply for a Residential Planned Community zone, which allows commercial, residential and business development, developers now must pay the county $22,220 plus $50 per acre. The previous rate, in effect until Friday, is $9,250 plus $20 an acre.

As in the previous fee schedule, there is no charge for owners who want their property designated as part of a historic district.

The newly approved fee schedule does provide a break for those applying for some types of special use permits. For example, the application cost for roadside stands, tourist homes, private businesses and churches will cost $25 less, or $525.

At a public hearing last night, the supervisors voted unanimously to buy the Ben Lomond Community Center for $300,000 from a local sanitary district. Officials said the purchase will mean that neighbors of the center near Manassas will no longer have to pay extra taxes to keep up the recreational facility. The neighbors voted to sell bonds through the sanitary district in order to build the center 10 years ago and have been paying for it ever since.