Following the lead of several other states, Maryland is preparing to sue the oil industry for the costs of cleaning up a one-time gasoline additive that’s contaminated  water across the state.

Maryland’s Board of Public Works approved Wednesday a plan by Attorney General Brian E. Frosh to hire a trio of outside law firms to seek damages from gasoline marketers and refiners for using methyl tertiary butyl ether, or MTBE, in motor fuel sold in the state.

The law firms — Berger & Montague of Philadelphia, Miller & Axline of Sacramento, CA, and the Law Offices of John K. Dema of Rockville — were chosen to represent Maryland in the MTBE litigation after state lawyers reviewed proposals from four different legal teams.

“The companies that caused this contamination should be held responsible for their actions,” Frosh said in a statement issued after the board action. “This legal team has the expertise and the ability to make Maryland whole from this environmental damage, and to ensure accountability. We are enlisting the resources we need to protect the public.”

MTBE was put in gas in the 1990s to help reduce ground-level ozone pollution, or smog. An estimated 1.2 billion gallons were blended with gas sold in Maryland from 1995 to 2001, according to the U.S. Energy Information Administration.

But MTBE often leaked from underground storage tanks, and became implicated in contamination of many drinking water wells.  Even small amounts can cause foul odor and taste in water, and the Environmental Protection Agency considers it a suspected carcinogen.

Though the industry stopped putting MTBE in gas in 2006, it has persisted in ground water for years. Nearly 12,000 underground gasoline storage tank leaks have been identified across Maryland, most of them involving service stations, according to state officials. 

Regulators usually require the source of a leak to clean it up. But the state has spent $18 million remediating contamination where no responsible party could be identified, according to a notice issued last year by the attorney general’s office when it was soliciting proposals from outside counsel.

Dozens of lawsuits have been filed nationwide over MTBE contamination by cities, states and municipal water suppliers. The suits allege the industry knew its additive was prone to leaking, and they seek to recover the costs of investigating and treating tainted ground water supplies.

In New Hampshire, a group of petroleum refiners agreed to pay the state $136 million in an out-of-court settlement. A jury trial later awarded the state another $236 million from the Exxon Mobil Corp., which had not participated in the earlier settlement.

The three law firms hired by Maryland jointly represent New Jersey in an MTBE lawsuit brought by that state, while two of the firms also represent Pennsylvania in another case.

Under Frosh’s plan, the firms would be paid out of whatever Maryland gets if the industry defendants settle or lose in court. Legal fees would range from 1 percent to 22.5 percent, depending on how much money is recovered and how much work is put into the litigation. No taxpayer funds would be paid to the firms, the attorney general’s office said, unless the state drops its lawsuit before the case gets resolved.

Exxon Mobil did not respond Wednesday to a request for comment.  In remarks to The Baltimore Sun last year, a company spokesman called such lawsuits “second-guessing” of the decision by the federal government to use MTBE in gasoline to fight air pollution. Todd Spitler, the Exxon Mobil spokesman, said the severity of ground water contamination has been rapidly decreasing since the industry ceased using it.