The Maryland Public Service commission is fining Washington Gas $750,000 in a case related to the 2016 gas explosion at the Flower Branch apartments in Silver Spring that killed seven residents and injured 65. The ruling is narrower, and the fine lower, than what some public safety advocates had hoped.

The fine has to do with gas regulator valves, which are the pieces of equipment that control the pressure of natural gas entering a building. In 2003, Washington Gas told the Public Service Commission it needed to replace more than 66,000 old regulators. The equipment, inside people’s homes, was 40 to 60 years old and contained dangerous mercury.

Washington Gas said at the time it would replace 550 regulators a month, upgrading all of them within a decade with new spring-loaded regulators. But the utility abandoned the project, and never told the Public Service Commission. Washington Gas told commissioners later it needed to focus on repairing gas leaks in Prince George’s County.

The gas regulator involved in the explosion at the Flower Branch Apartments was one of these old mercury regulators. It would have been replaced at least three years before the disaster in August, 2016, had Washington Gas completed the replacement program as planned.

According to the National Transportation Safety Board, a faulty regulator was probably one of the causes of the explosion.

The commission had to rule on two questions: whether Washington Gas should be fined for failing to complete the replacements, as the company said it would, and whether it should be fined for failing to report on progress of the project, which the utility also said it would do.

Commissioners decided to only impose a penalty for failing to file reports. The commission found the utility was overdue on 17 required yearly reports — they were cumulatively 55,845 days late. The maximum penalty, calculated per day, was $5,584,500, according to the commission’s ruling.

“However, the Commission finds that amount would constitute an excessive penalty for WGL’s failure to timely report in this case,” the ruling reads, referring to Washington Gas’s parent company.

Commissioners did not impose a penalty for failing to complete the gas regulator replacements.

One of the five members of the commission disagreed with that decision, in a concurring opinion. “I believe this case would warrant the Commission assessing WGL two separate penalties,” wrote Commissioner Michael Richard. “I remain convinced that further attention should have been given to the public safety deficit associated with WGL’s failure to complete the [mercury regulator replacement program],” wrote Richard.

“I was terribly disappointed in this outcome and frankly, in the entire process leading up to it,” said Del. Lorig Charkoudian, who represents the area in the Maryland General Assembly. Charkoudian said the $750,000 penalty was “not a lot of money” for a company the size of Washington Gas, and that the narrow ruling, focused on late reports, sends the wrong message.

“I’m disappointed in the decision that the public service commission itself made, but I’m also disappointed in all the structural things that are in place that allow a utility to essentially avoid accountability for the devastation that their systems caused,” said Charkoudian.

Washington Gas has disputed the NTSB findings. In a statement at the time, the company said it did not believe the evidence showed a failure of its equipment, and argued the NTSB “should have investigated other potential causes of the explosion.”

Washington Gas spokesperson Brian Edwards reiterated that argument: “The records show that mercury service regulators operate as safely as spring-loaded service regulators,” Edwards said.

Edwards said the company is now embarking on a new program to replace the old equipment. All mercury regulators should be replaced by 2027 — 14 years after the original deadline.