The City has 46 sanitary sewer lift stations. These pumping stations allow for the continuous flow of wastewater in areas of the city where gravity sewers are either ineffective or too expensive to build.
In 1997 the Sanitary Sewer Utility began a program to upgrade two lift stations per year. This program enables the City to ensure that all lift stations are operating effectively. A telemetry system allows lift station personnel to monitor station operations from a central location and respond immediately to emergencies.
The Western Lakes Superior Sanitary District (WLSSD) is the receiving and treatment facility for all Duluth wastewater. WLSSD bills the City for the cost of treating its waste based on the volume and quality of the waste. Quality is determined by the level of pollutants, in particular, BOD (Biochemical Oxygen Demand) and TSS (Total Suspended Solids) found in the waste stream. The district also monitors wastewater for other pollutants but charges to the City are based on volume, BOD and TSS.