Washington Gas has been ordered to pay a $750,000 fine for failing to notify officials it had not replaced mercury gas regulators such as the one blamed in a deadly 2016 explosion in Silver Spring, Md. The utility pledged more than a decade ago to replace all of its indoor mercury gas regulators, but never did.

In proceedings before the Maryland Public Service Commission, the utility said it decided to focus on addressing a surge of natural gas leaks instead. Washington Gas argued that its pledge to replace the regulators was a “plan” rather than a “commitment.”

The commission disagreed and found that Washington Gas should “at a minimum” have notified the commission that it was not honoring its commitment, said the order issued Friday.

“At no time did [Washington Gas] inform the Commission that it was addressing these leaks at the expense of its commitment” to replace the regulators, the order said.

The fine was based on the number of days over many years that the utility failed to file required annual reports on the replacement effort. The order also accepted a plan by the utility to replace its indoor mercury regulators within about six years.

Brian Edwards, a spokesman for Washington Gas, said that although the utility is moving forward with that plan, “it’s important to note that the Commission made no safety-related findings in the case, and the record shows that mercury service regulators (MSRs) operate just as safely as spring-loaded service regulators.”

The gas provider agreed to undisclosed settlements last year to end lawsuits filed by residents of the Flower Branch Apartments, where the deadly blast occurred.

Some in the community say the fine levied Friday didn’t go far enough. State Del. Lorig Charkoudian (D-Montgomery), in whose district the explosion occurred, said she was “shocked and dismayed” by a penalty she called “inconsequential.”

“The public safety implications of [Washington Gas’s] failure was massive,” Charkoudian said in a statement. She said the utility chose to “flagrantly abandon commitments” and should be held more accountable to discourage other utilities from doing likewise.

While seeking a rate increase in 2003, the gas provider said it would replace all 66,793 of its indoor mercury gas regulators over the next decade to address age and environmental concerns. The utility said it would deploy a staff of seven to replace more than 6,000 regulators a year for 10 years at a cost of about $200 per regulator.

The gas company cited the need to replace the regulators among many reasons it needed more money from customers. It received permission for the rate hike, but never delivered on its plan.

Three years after the regulators were to have been replaced, one became the prime suspect in an explosion that destroyed a building at the Flower Branch apartment complex, killing seven.

The National Transportation Safety Board concluded last year that a failed gas regulator and a disconnected vent line probably allowed gas to build up “to an explosive level” inside a basement meter room at the mostly low-income complex just outside Washington.

The resulting blast injured more than 30 and displaced more than 100.

The regulator and vent were owned and operated by Washington Gas and were the utility’s responsibility to maintain, NTSB investigators said. The regulators reduce the pressure of gas coming into a building. If a regulator leaks or fails, the vent pipe is supposed to carry gas safely outdoors, where it can dissipate.

Washington Gas officials have said that they disagree with the NTSB’s findings and that the agency didn’t sufficiently investigate other potential causes.

The utility has acknowledged it still doesn’t know how many regulators need replacing or where they are, and says it will undertake a survey to find out.

“After we complete this survey over the next year, Washington Gas will remove all multi-family MSRs [mercury service regulators] within 3 years and all single-family and other MSRs within 5 years,” Edwards said.