The Baker administration is violating the Clean Air Act and state law by opening the HOV lane on Interstate 93 north of Boston to all traffic, and it may soon have to defend that action in court, an environmental organization said Tuesday.

The state responded to the Conservation Law Foundation by saying the measure was only temporary and officials planned to meet with the group to talk about its concerns.

The CLF said in a statement that it had reminded the Baker administration that the HOV lane was created to improve traffic flow for carpoolers and buses — and was a “required component” of CLF’s settlement with the state in a lawsuit brought in the 1990s pushing for mitigation of emissions caused by the Big Dig.


The administration’s recent decision to open the HOV lane to all traffic while construction takes place on the Tobin Bridge violates the law, the CLF alleged. The CLF has notified MassDOT they will take them to court unless they reinstate HOV lane restrictions.

“With the daily traffic nightmare on our roads, opening this lane to all cars is short-sighted, slows commutes for bus riders, and violates the law,” Staci Rubin, a CLF senior attorney said in a statement.

“Punishing people for carpooling and taking public transit is the exact opposite of good policy. For the sake of our environment and the health and well-being of residents north of Boston, the state must realize its mistake and undo this change immediately,” she said.

According to the CLF, the state has 60 days to respond before a lawsuit can be filed.

Jacquelyn Goddard, a spokeswoman for the state Department of Transportation, said, “MassDOT does not plan to make this condition permanent.”

“The opening of the I-93 southbound HOV lane in Somerville and Medford,” she said, “is one of several temporary measures being undertaken by MassDOT to relieve North Shore congestion for all travelers related to the Route 1 Chelsea Viaduct and the Tobin Bridge projects.”


“MassDOT looks forward to meeting with CLF in the near future to address the group’s concerns,” Goddard said in an e-mailed statement.

Martin Finucane of the Globe staff contributed to this report. John R. Ellement can be reached at ellement@globe.com. Follow him on Twitter @JREbosglobe.