Manchester STP - Secondary Wastewater Treatment Plant in Manchester, Washington

Manchester STP is a municipal wastewater treatment facility located in Manchester, Kitsap County, Washington, United States. The plant serves a population of approximately 2,310 residents and operates as a secondary treatment facility, which is the standard for domestic wastewater in the region. As a secondary treatment plant, Manchester STP uses biological processes to remove organic matter and suspended solids. The plant has a designed capacity of 1,741.28 million gallons per year and currently discharges 757.08 million gallons per year. Under the U.S. Clean Water Act, such facilities are regulated by the National Pollutant Discharge Elimination System (NPDES) permit program, which sets effluent limits to protect water quality. The plant's treated effluent is discharged into the local watershed, which ultimately drains into Puget Sound, a major estuary in the Pacific Northwest. Puget Sound supports diverse marine life, including salmon, orcas, and shellfish, and is ecologically sensitive to nutrient pollution and contaminants. The plant's coastal location within 10 km of the sound underscores the importance of effective treatment to protect this vital ecosystem.

Manchester STP discharges into the local watershed that flows into Puget Sound, a large estuary connected to the Pacific Ocean via the Strait of Juan de Fuca. Puget Sound is a critical habitat for salmon, orcas, and shellfish, and is sensitive to nutrient loading and toxic pollutants. The plant's proximity to the coast (within 10 km) means that treated effluent can quickly reach marine waters, making effective secondary treatment essential for maintaining water quality and ecosystem health.