A bankrupt paper mill in North Carolina is refusing to take responsibility for millions of gallons of wastewater, polluted landfills, and toxic chemicals it produced, leaving state environmental regulators stymied and alarmed. “We’ve just never dealt with anybody who said, ‘We’re going to walk out the door and leave it,'” said Forrest Westall, the regional water-quality supervisor in nearby Asheville. Of primary concern is a lagoon containing as many as 500 million gallons of contaminated wastewater and sludge. Regulators fear that, with the plant closing, the power will be shut off, stilling the pumps that keep rainwater from flooding the lagoon and sending toxics into the groundwater. The state attorney general has ordered the mill owners to continue environmental monitoring and foot the bill for the $70 million to $200 million cleanup, but the owners say their obligations will end when the mill is sold.