The Ohio Supreme Court says an energy company is allowed to pass on the $55 million cost of cleaning up two polluted sites to its customers in the form of an added charge on their monthly bills.

Duke Energy has been adding $1.67 to bills in Ohio for about three years to help pay for the cleanup of two long-closed facilities in Cincinnati. A spokeswoman says the charge will likely continue for two more years.

The Supreme Court ruled last week that cleanup costs can be treated like other business expenses.

The Cincinnati Enquirer reports that Charlotte, North Carolina-based Duke Energy inherited the plants from another company. They were closed in 1928 and 1963, but cleanup had been a low priority because there was little public access to the sites.