The Arlington County Board approved the first step yesterday in a plan to preserve and renovate the 152-unit Westover Apartments, an aging garden apartment rental complex on Washington Boulevard that had been threatened with conversion to condominiums.

The board voted unanimously to authorize the Alexandria Redevelopment and Housing Authority to begin hearings on a proposed sale of $6 million in tax-exempt bonds to finance the project. The plan will come before the Arlington board again March 19 for final approval.

After voters overwhelmingly rejected the creation of an Arlington Housing Authority in a referendum two years ago, the county signed a cooperative agreement with the Alexandria authority to finance privately sponsored housing renovation projects in Arlington.

Under the agreement, the Alexandria authority provides private developers or private nonprofit housing corporations with low-interest, tax-free loans through the sale of revenue bonds.

The Arlington Housing Corp., a nonprofit agency that operates a variety of programs aimed at preserving affordable housing in the county, has a contract to buy and renovate the 46-year-old Westover complex, located on Washington Boulevard between Patrick Henry Drive and North Longfellow Street, the County Board was told.

Housing Corp. representative Austin Frum told the board that the group wants to set aside at least25 percent of the units for low- and moderate-income tenants. An estimated 61 percent of the current tenants are in that category.

Frum said the Housing Corp. had offers from three developers to buy its contract so that they could convert Westover to condominiums.

Board members said they regretted that more units could not be guaranteed for existing tenants, but agreed that the board should not pass up the opportunity to preserve the complex as rental housing.

Some residents of the Westover area said they feared the project could introduce "a dangerous element" to the community. But others argued that the rental housing is sorely needed, especially for the complex's large elderly population.