Since 1917, the Sanitary District of Decatur has been the wastewater treatment authority for central Macon County, Illinois. The District provides wastewater treatment for the residents and industries in Decatur, Mt. Zion, Forsyth, Argenta, and Oreana. The original treatment facility was built in 1924, and the current treatment plant was completed in 1990. Prior to 2019, about a half dozen carbon adsorber systems handled the odor control for the east side of the plant, which is located adjacent to a nearby neighborhood. The high concentrations of hydrogen sulfide (H2S) being treated made it very difficult to keep the carbon absorber systems online.