A challenge to a proposed special taxing district in Campustown appears to be brewing. Before the Ames city council approved the first reading of the self-supported municipal improvement district Tuesday night, planning and housing director Kelly Diekmann told the council his office had reviewed a draft petition opposing the district. Such a petition would require a unanimous council vote to approve the tax. The special tax levy would pay for snow and garbage removal as well as other improvements for properties within the district. Opponents who spoke at the meeting objected to a higher levy for mixed use properties while supporters said the levy would make Campustown more appealing to visitors.