Alderwood Water and Wastewater Dist - Snohomish County, Washington Wastewater Treatment Plant

Alderwood Water and Wastewater Dist is a major wastewater treatment facility serving Snohomish County, Washington, with a population equivalent of over 131,000. The plant is situated near Picnic Point, approximately 50 kilometers from the coast, and discharges into the Puget Sound watershed. As a large agglomeration, it plays a critical role in regional water quality management. The plant's designed capacity is 1. Under the US Clean Water Act, facilities of this scale are required to meet secondary treatment standards through National Pollutant Discharge Elimination System (NPDES) permits issued by the Washington State Department of Ecology. These permits set effluent limits to protect receiving waters. The treated effluent ultimately reaches Puget Sound, a major estuary that supports diverse marine life, including salmon, orcas, and shellfish. The plant's location near the coast means its discharge can influence nearshore ecosystems, making nutrient and pollutant control essential for maintaining water quality in the sound.

The plant discharges into the Puget Sound basin, which drains into the Salish Sea and eventually the Pacific Ocean. Puget Sound is a biologically rich estuary that supports critical habitats for Chinook salmon, Southern Resident killer whales, and Dungeness crab. The region's dense urban development and industrial activity place pressure on water quality, making effective wastewater treatment vital for protecting marine life and recreational uses.