Winthrop Sq. tower shadows could cause ‘great damage to historic buildings,’ Galvin says

A rendering of Millennium Partners' proposed building on the site of the Winthrop Square Garage. Handel Architects

William F. Galvin is not backing down over shadows on Boston Common.

In a letter to lawmakers Tuesday, Massachusetts’ secretary of state urged them to delay a key vote that would clear the way for a skyscraper on the site of Boston’s Winthrop Square Garage, saying shadows from the 775-foot tower could inflict “great damage to historic buildings” in downtown Boston, including the State House.

It’s the second time in two weeks that Galvin, whose office oversees the Massachusetts Historical Commission, has weighed in to slow the billion-dollar project. Before development plans can go forward, state legislators would have to amend 25-year-old laws restricting shadows on Boston Common and the Public Garden.

That process, Galvin said, is being pushed through without appropriate study by the developer, Millennium Partners, and Boston Mayor Martin J. Walsh — who is counting on the $153 million the city will receive when it sells the shuttered garage to Millennium. Galvin is urging closer scrutiny of the shadows’ effects — both on the parks and on historic buildings — before any vote.

“You can’t propose to do this without a complete study, but that’s what they’re talking about,” he said in an interview Tuesday. “I don’t understand the rush.”

City officials, though, note that shadows have been the topic of study and debate since November, when the Globe first reported the Winthrop Square tower would require a change in state law. They talked at length with parks advocates and with the City Council ahead of a 10-3 April vote by the council to change the laws. Even if the regulations are changed, the Winthrop Square project would face lengthy city and state environmental reviews, including more detailed shadow studies.

But that can’t happen until the project is legal, city officials say, which requires the change in the laws. By calling for a full study now, Galvin is confusing matters, said Brian Golden, director of the Boston Planning & Development Agency.

“We are disappointed that [Galvin’s] office is convoluting the process that will give the City of Boston an opportunity to invest hundreds of millions of dollars into our neighborhoods to improve our parks and public housing,” Golden said in a statement.

It was not clear Tuesday how lawmakers would respond to Galvin’s request for a delay.

Elected officials from Boston are largely on board with the bill — a priority for the Walsh administration — and a parade of supporters testified in favor of it last month at a hearing. Even former critics of the project, such as the Friends of the Public Garden community group, have muted their concerns since the City Council vote. Galvin was one of just a handful of critics to speak against it.

Still, the consummate Beacon Hill insider could prove to be problematic for Millennium and the mayor, even if the shadow laws are changed. The Historical Commission has broad power to review — if not necessarily stop — developments that might affect historic buildings.

A preliminary study already has such raised concerns, Galvin wrote to legislative committee chairs considering the shadow laws. He warned of “great damage to historic buildings,” new morning shadows “through the heart of the Public Garden (including the Swan Boats),” and “permanent moist conditions” even on inside walls of buildings that would receive less sun because of the tower.

“These are all important things we need to study,” Galvin said. “We have to ask these questions.”

Those questions and any others will be answered as part of the project’s standard environmental review, promised Joe Larkin, who’s leading the project for Millennium. But Larkin said it makes no sense to start that long and costly process until it’s clear the project can be built.

It’s been nearly a year since Millennium won the coveted rights to develop the garage site, a project it had hoped to start construction on this fall.

City officials and Millennium have often said they’re eager to get the project built before Boston’s current development boom dies out. That means it’s time to wrap up the shadow laws, Larkin said.

“It’s imperative that this legislation be passed before the summer recess” at the start of August, he said. “There are a lot of people who are asking for this project to move forward.”