The earliest wastewater treatment facility in the City of South Milwaukee was located on Hawthorne Avenue, close to Lake Michigan. By-products of the settling process were treated in drying beds near Third and Marquette Avenues.
In 1936, a primary treatment facility was constructed at the present site. In 1970, a secondary treatment facility was constructed at this site. In 1985, a new aeration system was installed and a process was added to dewater digested sludge. A 2.8 million gallon sludge storage dome and an ultra-violet disinfection system were added in 1996. In 2000, new primary clarifiers, a fine screen machine and a grit removal system were added to the facility. Currently, in 2008, raw influent pumps and a waste gas burner are under construction. Prior to this, the city embarked on a program of rehabilitation and independence, thereby separating the City of South Milwaukee from the Milwaukee Metropolitan Sewerage District. South Milwaukee had a combined sewer system, where the flows from both sanitary and storm sewers flowed to the treatment facility. Early developers of the city foresaw the potential problems with this, and separated the systems back in 1910.
Today, South Milwaukee remains independent and the treatment facility treats over 4 million gallons of wastewater every day.