The state plans to fine the energy company Eversource $1.5 million for safety violations related to a deadly gas explosion in a Maynard home in 2021.

In a "notice of probable violation," the state’s Department of Public Utilities cited Eversource for failing to properly classify, track and respond to gas leaks on a street in Maynard for years before a gas explosion destroyed a home there. The explosion was caused by a leaking gas line outside the home, and killed a man who flicked on a light switch while inspecting a "strange odor" in the basement.

The state also said that Eversource failed to monitor and remediate corrosion in pipelines, and used workers who were not properly qualified, including at least six contractors who responded to the incident.

In a statement, Eversource said the company strongly disagrees with the DPU's findings.

"The 2021 fire in Maynard was an isolated, tragic accident and we extend our sincere sympathies to family and friends impacted by it," the statement read. "We fully intend to work through the appropriate processes, as afforded to us through regulation, to present facts related to the information in this notice before any final resolution is reached.

"We take very seriously our daily work to maintain, modernize and upgrade our distribution systems to enhance safety and reliability for all of our customers in Massachusetts."

Nathan Phillips, a professor at Boston University who studies gas infrastructure, said it was “refreshing” to the see the state "holding a big and powerful utility to account with a credible and thorough investigation.”

However, he said the proposed fine was too low.

“The number and scope of violations was jaw dropping, and the penalty seems extremely light for the number and severity of violations,” Phillips said. He added that he was not surprised that overlooked and misclassified leaks led to an explosion.

“I could go out today and find hazardous leaks that are either misclassified by the utilities … or are not even on the books at all,” said Phillips. “But it never fails to be shocking, especially when an event like this is the outcome.”

Cathy Kristofferson, an organizer with the advocacy group Pipe Line Awareness Network for the Northeast, said the citation strengthened her opposition to Eversource’s planned construction of a gas pipeline in Springfield.

"It just raises concern for the quality of their work," she said.

Eversource is the largest energy delivery company in New England, with about four million customers in Connecticut, Massachusetts and New Hampshire. In Massachusetts, Eversource supplies gas to 117 communities.

The company has 30 days to respond to the department's findings.