Mayor Ted Wheeler left the door open for public money to help support a development anchored by a new major-league ballpark in Northwest Portland.

Wheeler said Friday he had told the Portland Diamond Project that the city wouldn’t pay for a stadium or buy a team.

But he said development fee waivers and tax breaks are still on the table. The city, he said, also could absorb some costs related to transportation and other infrastructure such as utility service.

“It would be very naive to assume there will be no public contribution in any large-scale economic development strategy, in any urban development we do,” he said. “It’s just way too early to tell.”

That could, he said, include financing infrastructure costs by borrowing against future tax revenue from the ballpark, a strategy known as tax increment financing.

The city has frequently made contributions to large-scale developments like the Pearl District and the South Waterfront. It also last year approved a relatively small tax break to the Portland Timbers, forgoing $2 million in ticket tax revenue from new seats created at Providence Park in the expansion currently under construction.

The project’s backers already have said they intend to tap $150 million in state-backed bonds already approved by the Legislature. The bonds would be paid back with an income tax on player and management salaries.

The development described by the Portland Diamond Project, the group of investors trying to lure a Major League Baseball team, would include housing and commercial development. The ballpark itself would take only about 15 acres of the 53-acre marine terminal they hope to lease.

Diamond Project has previously said it could act as a catalyst for at 8,000 apartments, including workforce and affordable housing. That’s an astronomical number even in the context of Portland’s waning building boom, but a desirable perk for a city with climbing housing costs.

The chosen site is zoned as prime industrial land, and its rezoning could prove controversial.

The city is required under state law to provide a 20-year supply of industrial land. Converting the terminal site to other uses could result in pressure to make it up elsewhere — like the aborted port terminal development at West Hayden Island, which environmentalists want to preserve as wildlife habitat.

The city is a key player in that dispute because it would have to annex the land. The port shelved plans to develop West Hayden Island in 2014 when the port said the city’s environmental mitigation requirements would be too expensive.

Bob Sallinger, the conservation director of the Audubon Society of Portland, said converting the ballpark site could renew the push to add industrial land.

“Industrial interests want to covert the land to make some money,” Sallinger said, referring to the port. “But the same interests will come back a year from now complaining about the lack of industrial land.”

Wheeler acknowledged the stadium would reduce the city’s industrial land supply, and that it was too early to say how that could be resolved.

But, he added, the port isn’t using the Terminal 2 site to its potential. The terminal is lightly used because its cargo-handling work can also be handled at the port’s Terminal 6 in North Portland, or at other regional ports.

The site is also underserved by public transportation, and access roads would likely need an upgrade to accommodate crowds in the tens of thousands arriving for games and other stadium events. The proposed ballpark would have 32,000 seats.

Wheeler said he’d convened a meeting Friday afternoon of key city agencies — including the Transportation Bureau, the Planning Bureau, the Development Services Bureau and the economic development agency Prosper Portland — to start the process of resolving the issues.

But he threw his support behind the site, which he said was preferable to the others that had been publicly disclosed.

“That’s the right place to pursue the vision,” he said.

-- Elliot Njus

enjus@oregonian.com; 503-294-5034; @enjus