Shirley Dept of Public Works Wastewater Treatment Plant, Ayer, Massachusetts

Shirley Dept of Public Works is a municipal wastewater treatment facility located on Brook Street in Ayer, Massachusetts, within Middlesex County. The plant serves a small population of 525 residents, reflecting its role in a rural or suburban community. It operates under the regulatory framework of the United States Clean Water Act, which requires secondary treatment for municipal discharges to surface waters. The plant provides secondary treatment, a standard biological process that removes organic matter and suspended solids. Its designed capacity is 378.54 cubic meters per day, with a daily discharge volume matching that figure, indicating full utilization. As a small facility, it is subject to EPA National Pollutant Discharge Elimination System (NPDES) permitting, typically administered by the Massachusetts Department of Environmental Protection. The treated effluent is discharged to a local water body, likely a tributary of the Nashua River or the Nashua River itself, which flows into the Merrimack River and eventually to the Gulf of Maine. The plant's operations help protect downstream aquatic habitats and water quality in the Merrimack River watershed, an important ecological and recreational resource in northeastern Massachusetts.

The plant discharges into a local stream or river within the Nashua River watershed, which drains into the Merrimack River and ultimately the Gulf of Maine. The Merrimack River supports diverse fish populations, including migratory species like Atlantic salmon and river herring, and provides drinking water for downstream communities. The plant's secondary treatment helps reduce nutrient and organic pollution, protecting these aquatic ecosystems.