Overview
Clatskanie STP is a secondary treatment plant serving 1,750 people in Clatskanie, Oregon. It discharges 757.08 m³/day of treated wastewater, operating under U.S. EPA NPDES regulations.
Clatskanie STP is a municipal wastewater treatment facility located in Clatskanie, Oregon, serving a population of approximately 1,750 residents. The plant is situated in Columbia County, near the Columbia River, and provides secondary treatment to meet state and federal water quality standards. The plant has a designed capacity of 1,892.70 m³/day and currently discharges 757.08 m³/day of treated effluent. As a secondary treatment facility, it utilizes biological processes to reduce organic matter and suspended solids. Under the U.S. Clean Water Act, such plants must comply with National Pollutant Discharge Elimination System (NPDES) permits, which set effluent limits to protect receiving waters. The treated wastewater from Clatskanie STP ultimately flows into the Columbia River, a major Pacific Northwest waterway that drains into the Pacific Ocean. The plant's operations help maintain water quality in the river, which supports salmon runs, aquatic habitats, and regional ecosystems. Its location within 50 km of the coast underscores the importance of effective treatment to prevent nutrient and pollutant loading to sensitive estuarine environments.
Environmental context
Clatskanie STP discharges into the Columbia River, which flows westward to the Pacific Ocean via the Columbia River Estuary. This estuary is a critical habitat for salmon, steelhead, and migratory birds. The plant's secondary treatment reduces organic pollutants and suspended solids, helping to protect downstream water quality in the river and the ecologically sensitive coastal zone.
Frequently asked questions
Clatskanie STP is located on Northwest 4th Street in Clatskanie, Columbia County, Oregon, United States.
The plant serves approximately 1,750 residents in the Clatskanie area.
The plant discharges treated effluent into the Columbia River, which flows to the Pacific Ocean via the Columbia River Estuary.
The plant operates under the U.S. Clean Water Act, which requires an NPDES permit issued by the Oregon Department of Environmental Quality. Secondary treatment is the minimum standard for municipal plants.
Small to medium-sized plants in the U.S. typically use secondary treatment, often with activated sludge or trickling filter processes, to meet NPDES permit limits for BOD and TSS.
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