On Sunday, the DPU confirmed it’s engaging in high-level talks with each of the state’s natural gas utilities — a group that includes Eversource’s two territories, the former NStar Gas area and the former Columbia Gas customers — to explore how to revise the delivery charge on their bills to minimize further price volatility for customers.

“We are reviewing the letter and will respond to the legislators who have contacted us,” DPU spokeswoman Alanna Kelly said in a statement. “We have listened to ratepayers, and we will be working directly with the gas companies over the coming days to revise their delivery rates to provide relief as soon as possible for their customers.”

Senator Jamie Eldridge, a Democrat from Acton, said in an email that he is grateful that his colleague, Senator Jake Oliveira, took the lead in drafting the letter.

“Over the past few weeks, as the winter has gotten colder, I’ve heard from dozens of constituents who are finding it harder and harder to pay their electric and gas bills, and our public utility agencies must take stronger action to reduce the financial stress on consumers,” Eldridge said.

Assuming no change in usage, rate changes approved by DPU that took effect on Nov. 1 drove the bills up 30 percent for a typical homeowner in the former Columbia Gas territory, for last month compared with January 2024. Meanwhile, the typical bill rose 23 percent in the former NStar Gas communities.

The senators implied that profit-making was behind the sharp increase in costs this season, but Eversource pointed to several other factors at play.

Eversource spokesman William Hinkle said profit for the company typically only makes up about 10 percent of a monthly natural gas bill. The primary drivers for this latest increase, he said, include more demand for the state’s Mass Save home heating efficiency program (reimbursed by a charge on utility bills), the commodity cost to procure natural gas on behalf of customers, and infrastructure improvements. The latter was particularly true in the former Columbia Gas territory; Hinkle said the company is still making investments that the state required as part of approving its purchase of Columbia Gas in 2020, following the disastrous explosions along gas lines in the Lawrence area two years earlier.

Hinkle said Mass Save costs represented 60 percent of the increase in the rates for former NStar Gas customers, and around 25 percent of the bills for former Columbia Gas customers.

That’s just what’s behind the fundamental rates. Hinkle also noted that this January was much colder than in previous years, prompting usage to go up. He cited figures showing average usage in Eversource territories rose 19 percent in January from the same time a year ago.

“Even if you don’t adjust your thermostat, … it takes more energy to get 65 [degrees] when it’s 10 degrees outside than when it’s 30 degrees,” Hinkle said. “The colder it gets, the more energy you use to get to that setting. The reason this crescendo has started now is because the increased usage has led to much higher bills, even though people have been living with these rate increases since November.”

Natural gas utilities typically adjust the supply portion of the bills twice a year, with the DPU’s blessing. But if supply costs rise or fall by more than 5 percent, Hinkle noted, an interim adjustment is necessary. The cold temperatures and New England’s gas supply constraints prompted a significant increase in wholesale gas prices this winter. As a result, Eversource adjusted gas rates again on Feb. 1, causing the typical bills to rise by 6 to 7 percent from what they would have been under the Nov. 1 rates, assuming similar usage levels.

As a result of the sharp increase in costs this winter, Eversource is holding webinars on Tuesday and Thursday this week to offer more information about its various payment plans and assistance programs.

“Affordability is a top priority for us,” Hinkle said. “We’re trying to address that every single day and help our customers with the tools that are available so they can better manage the cost of energy.”

Jon Chesto can be reached at jon.chesto@globe.com. Follow him @jonchesto.