The Highland Park Farmers Market will open in its usual location this month, but city officials say it needs a new, permanent home.

Duane Ashley, city director of community initiatives, and City Councilman Len Bodack are scouting potential locations so vendors can continue to sell their fresh produce.

The market, which is to open May 18 and run through November, is held in a parking lot next to Butler Street that is used by visitors to the Pittsburgh Zoo & PPG Aquarium. The market was started in 1980 and 40 to 50 vendors sell their goods there Thursdays from 3:30 to 7:30 p.m.

But progress, in the form of new exhibits at the zoo featuring polar bears, sea otters and walruses, along with two new ball fields, means the market will have to move, sooner or later.

Mr. Bodack, whose district includes Highland Park, said zoo officials want the market to move no later than July because that's when two male polar bears will arrive from the Denver Zoo. New exhibits always mean higher attendance, which is already up 44 percent over last year, and higher attendance means more car traffic.

B.J. Leber, chief of staff for Mayor Bob O'Connor, lives in Highland Park and patronizes the market.

"We don't have an alternative location to open the season. If it is at all possible, we will find a new location when the polar bear exhibit opens. If that's not possible, we will absolutely commit to a new location for the next summer," Ms. Leber said.

Between 4 and 6 p.m., with the market opening at 3:30, traffic congestion annoys zoo visitors and farmers market customers, said Frank Cartieri, the zoo's director of operations. As of May 27, when the summer hours go into effect, the zoo will not close until 6 p.m.

One day last summer, Ms. Leber said, "it took me 45 minutes to get from the entrance of the zoo and loop around to the market because all of the parents were picking up their kids from zoo camp. I know firsthand what the issues are."

Eric VandenHengel, a supervisor in the city's farmers market program, said eight years ago, the Highland Park Farmers Market grossed $2 million.

But, he added, market revenue began dropping four years ago when increased traffic made it harder for customers to enter and exit the zoo's parking lot without waiting in long lines.

Mr. Bodack agreed that the traffic problem "is only going to get worse when the exhibit opens," adding that the mayor's office has assured him police officers will be used to keep traffic moving.

In 2008, the market would have to move anyway because the city plans to start construction to turn the 675-space lot the farmers market uses into an extra large ball field that can accommodate two soccer games simultaneously.

Eventually, the zoo will build a new parking lot on land used by the city's Department of Public Works as a dump for leftover asphalt and grass clippings. The Public Works lot is used now for overflow on busy days, typically on the weekends, Mr. Cartieri said.

On Jan. 1, 1995, the zoo was privatized and taken over by the Zoological Society of Pittsburgh. City and zoo officials signed a 99-year lease on the land that requires the zoo to pay the city $1 per year.

The lease gives the zoo the first option to reuse the 18 acres it occupies. It has the right to create a parking lot where the city's maintenance dump is, Mr. Ashley said, because that's a higher use for the land.

After consulting their respective strategic plans, city and zoo officials worked a land swap that allows the soccer fields to be built along Butler Street in the lot used by the farmers market.

In the future, the zoo plans to reconfigure its Baker Street entrance.

Mr. Bodack said he is aware of all of these initiatives but his priority is to find a permanent location for the market as close to its current location as possible.

"It's the No. 1 revenue-producing farmers market," Mr. Bodack said. "People come across the [Allegheny] river to that market."

DeeAnna Cavinee, a Greenfield resident who founded Farmers Market Friends, said relocating a market "can actually lead to decline and sometimes the disappearance of markets."

Vendors are concerned about the uncertainty.

"We would just as soon start the season at a more permanent location. People get so confused," said Sandi Christoff, who, along with her husband, Jim, has sold produce and fresh herbs at the market since it opened.

Mr. Bodack said he has looked at several sites, including Reservoir Drive, which circles one of the Highland Park reservoirs, and Mount Bigelow, a higher point in the park with a view of the Allegheny River.

Another option is on 50th Street, at a parking lot on property owned by the Rubinoff Co.

"It's a stone's throw from Butler Street," Mr. Bodack said, but the city would have to pay rent and that does not seem likely.

A fourth option is Lawrenceville's Arsenal Park, which is bounded by Penn Avenue, 40th and 39th streets, and Butler Street.

"In that situation we may have enough parking," Mr. Bodack said, adding that such a move would affect residential parking in that neighborhood.

Mr. Ashley is not sold on moving the market to Lawrenceville because it would force some customers to drive farther.

"It's essentially creating a new market. It's no longer an extension of the Highland Park market," Mr. Ashley said, adding that customers come from Shadyside, East Liberty, Morningside, Highland Park and Aspinwall.

"That's why we looked internally to Highland Park, so we could maintain the existing customer base," he said.