Columbia Gas agreed Tuesday to notify local fire departments about potentially dangerous gas leaks in the Merrimack Valley immediately, a change from their previous procedure that fire chiefs have been pushing for.

Massachusetts state law requires gas utilities to notify the local fire department of gas leaks that are classified as a grade one leak, which means they pose a hazard to persons or property, but doesn't specify when they must do so. Columbia Gas had been sending the local department an email the day after a potentially hazardous leak was fixed, much to fire department chiefs' frustration.

The change in practice comes as the Merrimack Valley fire chiefs are seeing an increase in reported gas leaks in the area since September's fires and explosions.

After meeting with Columbia Gas executives on Tuesday, Chief Bill McCarthy of the North Andover Fire Department said the utility agreed to address fire departments' concerns about when they get notified about leaks.

“If they get a call from the public that there's an odor of gas out in the street ... they will in turn notify us immediately so we can we can have a response in that area,” McCarthy told WGBH News.

Columbia Gas confirmed to WGBH News that it now plans to reach out immediately to the fire departments about gas leaks in the three affected communities, and in neighboring Methuen.

Read more: Columbia Gas And Its Corporate Parent Have History Of Late Accident Reporting And 15 Explosions in 8 Years

Sen. Ed Markey expressed frustration at the slow notification process at a U.S. Senate field hearing in Lawrence last month.

“They don't call the fire department. They don't call the police department. They fix it as best they can," Markey said. "Then they call [the fire department] the next day or two days later [and] say, ‘Oh we had a big problem, but we didn't feel we had to call you — the fire department, the police department, of the city.’ Is that correct?"

"That is correct," Andover Fire Chief Michael Mansfield answered. The grade one leak is the worst-case scenario of a natural gas leak you could possibly have, and that's it in their infrastructure.”

State Rep. Lori Ehrlich was pleased when WGBH News told her Columbia Gas is changing its policy. Ehrlich has been working on a bill to amend the existing state law to require utilities to notify fire departments of grade one leaks right away, rather than after the fact. But despite the change at this one utility, she still plans to introduce that bill.

"I'm even more motivated now to formally file this bill," Ehrlich said.

Ehrlich said Columbia Gas proved this week that the notification issue can be resolved. Some other gas utilities in the state say they do already let local fire officials know as soon as a grade one leak is discovered, though as of now, nothing in state law requires them to do that.

The Merrimack Valley fire chiefs also said they’ve seen an increase in reported gas leaks in the area since the tragic fires and explosions there in September.

There have been more than 40 gas leaks that are classified as a grade one leak in the three affected communities since the Sept. 13 explosions, fire chiefs from Andover, Lawrence and North Andover told WGBH News.

“We’re seeing gas leaks in area of the pipeline that was replaced already," Andover Fire Chief Michael Mansfield said. "And certainly that’s a concern and certainly if it’s happening now, it’s going to continue to happen.”

Lawrence Fire Department Chief Brian Moriarty also said his department's calls for gas odors and gas leaks have "increased dramatically" since Sept. 13.

In a written statement, a Columbia Gas spokesman said some leaks were discovered during safety checks of newly installed pipelines, which he said is normal for a project of this size and scope. The utility addressed those leaks immediately and there is no threat to the public, the spokesman said.