Overview
CENTRALIA STP serves 17,140 people in Lewis County, Washington. The plant operates under the US Clean Water Act and NPDES permit program.
CENTRALIA STP is a municipal wastewater treatment plant located in Lewis County, Washington, serving a population of approximately 17,140. The facility is part of the region's wastewater infrastructure, managing effluent from residential and commercial sources in the area. As a US-based plant, CENTRALIA STP operates under the Clean Water Act and is subject to National Pollutant Discharge Elimination System (NPDES) permits issued by the Washington State Department of Ecology. For a population of this scale, secondary treatment is typically required, with additional nutrient removal if discharging to sensitive waters. The plant's treated effluent is discharged into the Chehalis River basin, which flows westward to Grays Harbor and the Pacific Ocean. The Chehalis River supports diverse aquatic life, including salmon runs, and the plant's discharge must meet water quality standards to protect downstream ecosystems.
Environmental context
The plant discharges into the Chehalis River watershed, which drains to Grays Harbor and the Pacific Ocean. This river system supports critical salmon and steelhead habitats, making water quality management essential for maintaining healthy fish populations and overall aquatic biodiversity in the region.
Frequently asked questions
CENTRALIA STP is located at 1084 Goodrich Road, Lewis County, Washington, United States.
The plant serves a population of 17,140 people in the Lewis County area.
The plant discharges treated effluent into the Chehalis River basin, which flows to Grays Harbor and the Pacific Ocean.
As a US municipal wastewater plant, CENTRALIA STP operates under the Clean Water Act and is regulated by an NPDES permit issued by the Washington State Department of Ecology, which sets limits on pollutants to protect water quality.
For a population of this size, secondary treatment is standard under the Clean Water Act. Depending on the receiving water body's sensitivity, additional nutrient removal may be required to meet state water quality standards.
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