The first sanitary sewers were installed in Burlington in 1946. A "trickling filter" type of treatment plant was constructed at that time, consisting of a primary clarifier, trickling filter, secondary clarifier, chlorine disinfection, and anaerobic digester. It was located on Railroad Street and was one of the first secondary-treatment wastewater plants in Washington state.
In 1974, with the help of state and federal funding, a new wastewater treatment plant was built on Section Street and remains in service today. In 1976, the sewer system was extended west to serve the Skagit Country Club area and the Port of Skagit County Business Park. A connection was also made to the Lake Samish system and Burlington began providing secondary treatment to the wastewater discharged from their primary treatment lagoons.
In the year 2000, the Section Street wastewater plant was upgraded and enlarged to keep pace with the growth in our service area. The project more than doubled our capacity, switched from aerobic to anaerobic digesters, and from chlorine to ultraviolet disinfection.