Raw sewage is backing up into basements and backyards of some homes in Mason City near where a private sewer system connects to the city’s main sewer line. Cerro Gordo County health director Ron Osterholm says they’re investigating the cause of the problem and are working on a rapid solution. Osterholm says the health threat is potentially very serious and he hopes it can be quickly resolved. He says they want to get rid of the waste due to the health problems and they want to be sensitive to the financial problems involved. An intensive fund drive organized Thursday by a Mason City hospital and other entities generated more than 12-thousand dollars to help solve the problems.