Immediately after the establishment of the BSA in 1934, a primary wastewater treatment plant at Bird Island was constructed and began operations on July 1, 1938. The original treatment plant was constructed with a hydraulic capacity of 570 MGD and consisted of bar screens, grit removal equipment, primary settling tanks (clarifiers) and disinfection facilities. Solids generated during the treatment process were disposed of in three multiple hearth incinerators. In conjunction with the construction of the plant a number of pump stations were constructed throughout the City to collect and transmit wastewater to the Bird Island treatment plant. The South Buffalo Pumping Station was built in 1938, the Hamburg Street Pumping Station was built in 1939, and the East Amherst Street Pumping Station was built between 1948 and 1949. Finally, intercepting sewers to convey flow to the WWTP were constructed between 1936 and 1939. The terminus of the intercepting sewers is located at the gatehouse on the mainland side of the City across the Black Rock Canal from the WWTP. The terminus of the collection system consisted of two 8-ft diameter concrete inverted siphons that to this day convey wastewater under the Black Rock Canal to the WWTP.
The Bird Island WWTP operated in this configuration until the mid-1970s when in response to the federally mandated Clean Water Act, the BSA upgraded the plant to meet new secondary treatment standards. Secondary treatment facilities were added at the plant between 1975 and 1979. Under this upgrade, aeration and secondary clarification equipment were added along with upgrades to the disinfection system. Upgrades to the facility allowed for improved treatment for up to 360 MGD of flow. Flows in excess of the secondary treatment system capacity are treated through the original primary facilities or a combination of both primary and secondary. Currently the Bird Island WWTP is the second largest plant in New York State with a design average flow of 180 MGD. Since the secondary plant was constructed, the BSA has continued to improve and upgrade other areas of the plant with over $30 million of capital investment made in the past 10 to 15 years alone.