The Water Quality Control Division is responsible for the collection and treatment of the City’s wastewater and
stormwater, and is housed in two locations – a primary treatment facility located on Sutter Avenue and a secondary
treatment facility located about seven miles away on Jennings Road.
In addition to treating wastewater from industrial and residential sewer lines, the division also includes:
- A testing laboratory and Environmental Compliance Sections that ensure compliance with water, wastewater,
and storm water regulations;
- The Storm Water and Wastewater Collections Sections that maintain the industrial and domestic lines, rockwells,
storm drain lines and lift stations;
- The SCADA (Supervisor Control and Data Acquisition) system that provides real-time monitoring and control of
63 sewage and storm water pump stations, 150 drinking water wells, reservoirs and pressure points and the two treatment
The Water Quality Control Division treats an average of 25 million gallons of wastewater per day received from Modesto
residents and businesses. The treated water is cleaned in compliance with the City’s National Pollution Discharge
Elimination Standards (NPDES) Permit and is released to either the San Joaquin River (between October and April) or to
farmland for irrigation (during the remainder of the year). The bio-solids created during the process of cleaning the
water are combined with pruned refuse and other organic matter to enrich the compost and return the nutrients to the soil.