BOSTON — The state's aging natural gas pipelines are still riddled with thousands of potentially dangerous and damaging leaks, according to a new report.

The report, compiled by environmental groups using data from publicly regulated utilities, found at least 15,728 gas leaks statewide at the end of 2019, some of them dating back several years. A majority are "grade 3" leaks, considered the least dangerous, but the report's authors note that any leaking combustible gas is a hazard.

"Gas leaks are potentially explosive, kill trees, harm human health and release destructive greenhouse gas," said Audrey Schulman, president of the Home Energy Efficiency Team, a Cambridge nonprofit that mapped the data.

To be sure, the report shows utilities made progress fixing gas leaks last year, with at least 11,401 repairs.

A 2014 law requires the utilities to track and grade all gas leaks on a scale of 1 to 3, with 1 being most serious, and immediately repair the most hazardous. The law also requires utilities to share the information with the public.

Utilities say the majority of leaks are minor and pose no safety threat. Serious eruptions of gas lines, often reported by residents, are dealt with swiftly, they say.

Rep. Lori Ehrlich, D-Marblehead, called the latest data in the report "disappointing" and said utilities aren't moving quickly enough to fix the leaks.

"Though the number of leaks is slightly lower, it's nothing to celebrate," she said. "After more than a decade of new laws and deadly explosions that traumatized a whole region of our state, the gas companies have not come close to providing our state a closed system for their explosive gas."

Sen. Barry Finegold, D-Andover, said the lack of progress on fixing leaks since the 2018 Merrimack Valley gas fires and explosions is troubling.

"There's still way too many leaks," he said. "We know it's inevitable there will be some gas leaks, but we need a stronger commitment to fixing them."

The latest HEET report, posted at, includes an interactive map allowing viewers to search by town and zoom-in on neighborhoods.

Utilities say they're addressing the smaller leaks by replacing old iron distribution pipes with newer plastic and coated steel pipes, which are less prone to leaking.

Eversource spokesman Reid Lamberty said his company monitors all of its leaks and "goes above and beyond state and federal requirements."

"We survey more frequently than required and repair hazardous leaks immediately," he said. "Most outstanding leaks on our system are classified as Grade 3, non-hazardous leaks, and most of these will be removed or repaired over the next several years with future system enhancement projects."

Data from the HEET report shows that Eversource repaired 1,147 leaks last year and had another 2,583 leaks that were un-repaired. Eversource is in the process of acquiring Columbia Gas of Massachusetts in a $1.1 billion deal.

Columbia Gas reported repairs of 2,604 leaks in 2019, with another 1,946 left unrepaired at the end of the year.

A spokeswoman for National Grid said the company has ramped up efforts to replace miles of gas lines, which are among the nation's oldest.

"Accelerating the rate of main replacements is the best long-term approach to reducing leaks on the gas system and enhancing overall safe operations," National Grid spokeswoman Christine Milligan said in a statement. "Over time, accelerated main replacement will significantly reduce leak rates."

But Milligan said upgrades come "at a significant cost."

"The challenge is balancing the need to invest in our gas system while, at the same time, maintaining stable gas rates for our customers," she said.

Christian M. Wade covers the Massachusetts Statehouse for North of Boston Media Group’s newspapers and websites. Email him at


Leaking Gas

Here's some information on gas leaks, which was compiled using 2019 data from publicly regulated utilities.

City/town Repaired gas leaks Un-repaired gas leaks

Beverly 149 142

Salem 107 71


Peabody 37 161

Marblehead 115 147


Gloucester 37 75

Andover 54 75

Lawrence 214 97

North Andover 49 38

Newburyport 35 44

Methuen 243 126

Haverhill 93 147

Total statewide: 11,401 15,728

Source: Home Energy Efficiency Team/Gas Leaks Allies



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