New Hampshire's top court on Oct. 2 upheld a $236 million judgment against Exxon Mobil Corp over groundwater contamination linked to gasoline additive MTBE.

The New Hampshire Supreme Court ruling affirms a 2013 jury decision that rejected Exxon's claims that contamination linked to the fuel additive was the fault of the local gas stations and storage facilities that spilled it.

In the 1990s, in response to U.S. clean air regulations, MTBE was commonly added to gasoline to reduce smog. Subsequent studies found that the chemical easily penetrated and contaminated groundwater, and its use was gradually phased out.

New Hampshire's lawsuit against Exxon, which is headquartered in Irving, Texas, dates back to 2003. State officials say the $236.3 million judgment is the largest MTBE verdict since states and other agencies began making the claims for remediation and other damages.

"This is the most significant environmental victory in the history of the state," New Hampshire Attorney General Joseph Foster said in a statement on Oct. 2. "This historic decision sends a clear message that New Hampshire will not permit polluters to endanger the health of its citizens and destroy its natural resources."

A spokesman for Exxon said on Oct. 2 that the company is considering appealing the case to the U.S. Supreme Court.

"MTBE contamination has been found in New Hampshire because someone spilled gasoline in New Hampshire, not because it was added to gasoline in a refinery in another state," spokesman Todd Spitler said in an email.

"The state should have sued the parties responsible for spilling gasoline, not the refiners who were compelled by law to add oxygenates to gasoline," he said.

In 2014, Exxon appealed to the U.S. Supreme Court a $105 million jury verdict in favor of New York City over MTBE contamination, but the court declined to hear the case, letting the decision stand.

According to New Hampshire officials, more than 600 wells in the southern part of the state are contaminated with MTBE.

New Hampshire has received $90 million in legal settlements with other gasoline suppliers over MTBE contamination. The state has yet to receive any compensation from Exxon.