1930s

The Green Bay Metropolitan Sewerage District was formed December 4, 1931, with the first treatment plant beginning operation early in 1935. The condition of the river water was bad enough that, even in the Depression 30s, people were concerned enough to raise the $1,800,000 needed to construct the plant.

This first facility, with a capacity of 10 million gallons per day (MGD), included two primary clarifiers and chlorination for treatment of the wastewater. Treatment at that time averaged 2.5 MGD.

This was better than no treatment at all, but it soon became evident that it also wasn't enough.

1950s

Area growth and a desire for improved water conditions led to several plant expansions from 1935 through the 1950s.

In 1955, a secondary treatment system, using trickling filters, was installed to biologically treat the water and remove wastes more extensively. The design capacity of the plant at this time was 22 MGD, though treatment averaged about half that initially.

Also, during the middle 1950s, work began on the separation of storm and sanitary sewers. That way, storm water wouldn't be filling up the system, and treatment could focus on the more concentrated wastes.

1970s

In the early 1970s, federal clean water regulations mandated tougher water quality guidelines.

GBMSD, in anticipation of stricter regulations, began in the late 1960s by conducting intense research on the feasibility of treating domestic sewage and pulp mill discharge.

This effort culminated in a $72 million expansion project, which utilized activated sludge in its secondary treatment process. Not only was this process more effective at removing waste from the water, but it also allowed GBMSD to be the first plant in the nation to simultaneously treat municipal and pulp mill wastewater, setting a precedent in the fight against water pollution.

With the planning stages beginning as early as 1963, the plant was completed in 1975 and had a capacity of 52 MGD.

1990s

Based upon more stringent effluent standards, GBMSD's 1990s expansion took another large stride toward cleaner water. With the addition of two aeration basins, two clarifiers and an improved solids handling system, the plant greatly improved its ammonia removal efficiency.

Additional facilities provided for dechlorination of the effluent (treated water leaving the plant).

The capacity of the plant dropped just a bit to 49 MGD. Even though additional basins were added to the facility, the process was changed and treatment required a greater detention time. This greater detention time allows for more efficient removal.

Allowances were made in the design to facilitate future expansions as growth and regulations demand.