The treatment plant was constructed in 1938 and has been upgraded every ten years as industry and population increases in the City of Belleville. The plant is currently being expanded as part of the City’s Long Term Control Plan. The expansion will increase the plant's treatment capacity to 12.8 million gallons a day (MGD) from the existing 8 MGD. The additional capacity of the expanded plant would potentially serve an estimated 120,000 residents setting the City up for future residential, commercial, and industrial growth. View the Long term control planandLong term control plan schedule.