Mayor Martin J. Walsh’s bid to get a skyscraper built on a city-owned garage scored a big win Wednesday when the Boston City Council agreed to amend the law that protects Boston Common and the Public Garden from building shadows.
Council members voted 10-3 to rewrite 25-year-old laws restricting shadows on the two historic parks, which would allow Millennium Partners to build a 775-foot tower in Winthrop Square. Preliminary studies by the developer show the building would cast additional shadows on both parks during certain times of the year.
The change to the shadow law now needs approval from the Massachusetts Legislature.
Millennium has agreed to pay the city $153 million to buy the shuttered Winthrop Square Garage, and Walsh administration officials have said the deal provides a “once-in-a-generation” chunk of cash, which it plans to use for improvements to parks and public housing in Boston.
That argument won over most of the councilors.
“We will never see another project that will have so much impact on so many neighborhoods of Boston,” said Councilor Matt O’Malley. “I’m voting yes.”
But a few councilors remained troubled, arguing the city should not be putting a one-time payday before the two parks, and that the deal was being pushed through with no study of alternatives.
“We need to be advocating for these resources on a daily basis, on a macro level,” said Councilor Josh Zakim. “We’ve been presented with a binary, all-or-nothing proposal here.”
The proposal from Walsh would allow the additional shadows from the Winthrop Square tower, but would also limit how much more shadow could be cast on the parks by any other new buildings. It would also tighten limits on shadows from new buildings in Copley Square.
The vote followed a marathon public hearing Monday at which councilors grilled Walsh aides on the complex deal, and took testimony from dozens of supporters and opponents.
Wednesday’s vote took less time, and was more subdued. Just a handful of opponents — wearing yellow buttons urging protection of the parks — came to watch the debate, alongside executives from Millennium and project supporters.
After the vote, the Millennium Partners executive in charge of the Winthrop project said he was heartened by the margin.
“10-3 is a big number and [council members] spoke in a big way,” Joe Larkin said. “It sends a message from the city.”
The next, and potentially trickier, step will come next, at the State House, where state lawmakers must also approve the change.
Brian Golden, director of the Boston Planning and Development Agency, said the Walsh administration had already sounded out state legislators from the city as they crafted the complex bill, and are now looking for one to sponsor it, with the aim to have it passed before summer. Like Larkin, he said the strong vote in City Hall will make their job easier.
“We’re going to the state with a good story to tell,” Golden said.
Still, two key lawmakers — Representative Aaron Michlewitz, whose district includes Winthrop Square, and Representative Byron Rushing, who co-authored the original shadow bill — have thus far been noncommittal.
“I haven’t seen the final language,” Rushing said. “We’re going to review that and see what we can do.”
Michlewitz, who has said he wants the city use some Winthrop Square proceeds to fund the Rose Kennedy Greenway, did not return messages seeking comment.
Opponents such as Vicki Smith of the Neighborhood Association of the Back Bay, who said she was “not very happy” with the council’s vote, said they will now take aim at state legislators.
Still, any further negotiations about details of the bill could be limited, as any changes made by state legislators would have to come back to the City Council. Golden said he’d like to avoid any more delay for $1 billion project, already years in the making.Tim Logan can be reached at firstname.lastname@example.org. Follow him on Twitter at @bytimlogan.