Recent history includes an incident involving groundwater contamination. A test of the groundwater conducted on September 14, 2001, showed that the water contained the ether MTBE (methyl tertiary-butyl ether) at levels of over 350 ppb (parts per billion). This was the first public statement concerning the presence of MTBE in Pascoag drinking water, though residents claim to have detected it as early as May 2001. MTBE is a gasoline additive intended to enhance octane levels. It is believed to have come from leaking tanks at a local Exxon Mobil gas station. As the situation was resolved over the following months, nearly 1,500 residents of Pascoag responded by filing a lawsuit against Exxon Mobil through the law offices of Napoli, Kaiser, and Bern and Houston attorney Armistead Easterby. Exxon Mobil signed off on a $7 million settlement with residents of Pascoag in May 2012, to cover the cost of having the Pascoag Public Utility District bore new wells.