Upper Blackstone Water Pollution Abatement District - Millbury, Massachusetts Wastewater Treatment

The Upper Blackstone Water Pollution Abatement District is a major wastewater treatment facility located in Millbury, Massachusetts, serving a population of approximately 207,535. It is the primary treatment plant for the Worcester metropolitan area and several surrounding communities in central Massachusetts. As a large agglomeration serving over 200,000 people, the plant operates under the U. S. Clean Water Act, administered by the Massachusetts Department of Environmental Protection. Facilities of this scale are typically required to provide advanced secondary or tertiary treatment to meet stringent National Pollutant Discharge Elimination System (NPDES) permit limits, particularly for nutrients such as nitrogen and phosphorus. The plant's treated effluent is discharged into the Blackstone River, which flows south through Massachusetts and Rhode Island before emptying into Narragansett Bay. The Blackstone River watershed is ecologically significant, supporting diverse aquatic life and providing habitat for migratory fish species. The plant's operations are critical to protecting downstream water quality in the river and the bay.

The plant discharges into the Blackstone River, a tributary of Narragansett Bay via the Seekonk River and Providence River. The Blackstone River watershed spans over 500 square miles and supports a variety of fish species, including American shad and river herring. Downstream, Narragansett Bay is a large estuary that provides critical habitat for marine life and supports commercial and recreational fisheries. Nutrient loading from upstream sources can contribute to algal blooms and hypoxia in the bay, making advanced treatment at this plant important for regional water quality.