Coos Bay STP No 2 Empire Wastewater Treatment Plant, Coos Bay, Oregon

Coos Bay STP No 2 Empire is a municipal wastewater treatment plant located on Fulton Avenue in Coos Bay, Oregon. It serves a population of about 9,800 people, placing it in the small-to-medium agglomeration category for US wastewater infrastructure. As a US facility, the plant operates under the National Pollutant Discharge Elimination System (NPDES) permit program, administered by the Oregon Department of Environmental Quality. The Clean Water Act requires secondary treatment for municipal plants of this scale, with effluent limits designed to protect receiving water quality. The plant's designed capacity is 1.00 million gallons per day, indicating it is sized for its service population. The plant's treated effluent discharges into the Coos Bay estuary, which flows into the Pacific Ocean. The estuary supports diverse aquatic life, including salmon runs and migratory birds, making proper treatment essential for maintaining ecological health in this coastal environment.

The plant discharges into the Coos Bay estuary, a coastal inlet on the Pacific Ocean in southern Oregon. The estuary is part of the larger Coos River watershed and provides critical habitat for Chinook salmon, steelhead, and numerous bird species. As a coastal discharge, the plant must meet stringent water quality standards to protect both estuarine and marine environments from nutrient loading and pathogen contamination.