On Thursday, the State of Alaska filed a law suit against the current and former owners of North Pole's Flint Hills Refinery for the costs of cleaning up the local polluted water supply.

According to the suit, filed Thursday against Williams Alaska Petroleum Inc. and Flint Hills Resources, in 2008 a plume of the refining chemical sulfolane was found to have leaked away from refinery property and into the groundwater around the refinery. The chemical had been traveling through groundwater underneath North Pole, in a plume that measured 2.5 by 3 miles wide.

The state Department of Environmental Conservation and Flint Hills worked together to test residential and city wells. Homeowners off city water had a choice of using holding tanks or a filtration system. The city's wells were replaced, although at the time their contamination levels were below the legal limit. In a pamphlet sent out to the homeowners of North Pole, Flint Hills claimed to have spent $70 million in cleanup costs.

The state's suit against Flint Hills and Williams is only the latest litigation they face. In 2010, North Pole homeowner James West sued both firms over the groundwater contamination and the potential health risks he and his family might have faced for the pollution.

Little is known about the long-term health effects of sulfolane exposure. The State Department of Health and Social Services says rats have showed symptoms of liver, kidney and spleen damage, as well as reduced white blood cell counts (PDF), after being exposed to much higher levels than what was reported in North Pole water.

Flint Hills eventually joined West as a plaintiff and West was dropped, leaving the lawsuit to be Flint Hills vs. Williams. In court records, Williams indicated that the statute of limitations had passed for the company to be held responsible for clean up.

In court documents, the state claims Williams knew there were spills on the facility property. According to court papers, Williams paid for a $50 million cleanup insurance policy as part of the sale agreement.

Flint Hills spokesperson Jeff Cook said in response to the new suit, "We view it as a positive development to ascertain who's responsible and for the ongoing costs up to date, to clear up the contamination and clear up the property,"

Williams did not respond to requests for comment before deadline of this story.

The contamination in North Pole affects about 300 households. Flint Hills has either provided those homes with water or installed a water filtration system.

The company also replaced wells for the city of North Pole.