The Journal Star did a good job of covering this:

By a 9-1 vote, the City Council approved a tax on natural gas usage, which would equate to roughly $24 to $25 a year for the typical residential customer of Ameren Illinois….

Originally, the council had planned to approve a 3.5-cent-per-therm – a measurement of gas use – tax that would generate $6 million a year, resulting in $32.97 more in annual residential bills.

Fourth District Councilman Bill Spears, though, recommended a cheaper 2.5-cent-per-therm tax [which could generate roughly $4.3 million annually].

Proponents of the new revenue stream say it will allow the City to keep those police and firefighter positions that were threatened to be eliminated. They also point out that the tax applies to all natural gas users, including non-for-profit institutions like hospitals and churches, thus spreading the pain among a larger base than other proposed taxes. Critics say it protects wasteful spending that should be cut first before new revenues are added. They also say it will present a hardship on many households, especially those on a fixed income, and at the worst possible time — as we’re heading into winter.