Coos Bay STP No 1 - Municipal Wastewater Treatment Plant in Coos Bay, Oregon

Coos Bay STP No 1 is a municipal wastewater treatment plant serving the city of Coos Bay, Oregon, on the southern Oregon coast. The plant handles wastewater from a population of about 13,000 residents, placing it in the small-to-medium agglomeration category under US regulatory frameworks. As a US facility, the plant operates under the Clean Water Act and is subject to National Pollutant Discharge Elimination System (NPDES) permits issued by the Oregon Department of Environmental Quality. Plants of this scale typically employ secondary treatment as a minimum standard, with possible nutrient removal to protect sensitive coastal waters. The plant's treated effluent discharges into Coos Bay, a coastal estuary that flows into the Pacific Ocean. This estuarine environment supports diverse aquatic life, including salmon runs and shellfish populations, and is an important ecological corridor for migratory birds. The plant's proximity to the coast underscores the need for effective treatment to protect marine water quality.

Coos Bay STP No 1 discharges into the Coos Bay estuary, which connects to the Pacific Ocean. This estuarine system is ecologically sensitive, supporting critical habitats for fish, shellfish, and migratory birds. The plant's location within 50 km of the coast means its effluent can influence nearshore marine water quality, making nutrient and pathogen control important for maintaining healthy aquatic ecosystems.