This is part of a trend in Michigan.
As municipal governments wrestle with tight budgets, more and more they are turning to special taxes to supplement the regular property taxes that normally would pay for those services. For example, many cities now will propose a special millage for police or fire. That's because people will probably vote to support police officers on the street.
This is partly driven by plunging city revenues caused by a defective system of municipal funding, but that will be the subject of another post.