Toledo STP - Secondary Wastewater Treatment in Toledo, Washington

Toledo STP is a municipal wastewater treatment facility located on South 1st Street in Toledo, Lewis County, Washington. Serving a population of approximately 540, this plant is part of the small community's infrastructure for managing domestic wastewater. The plant operates under the regulatory framework of the US Clean Water Act, which requires secondary treatment for municipal discharges to surface waters. The plant provides secondary treatment, a biological process that removes organic matter and suspended solids. With a designed capacity of 560.24 volume units and an average daily discharge of 280.12 volume units, the facility operates at about half its capacity, indicating room for future growth. As a small-scale plant, it is subject to Washington state's water quality standards and NPDES permitting requirements. The treated effluent from Toledo STP is discharged into a receiving water body within the Columbia River basin, which ultimately drains to the Pacific Ocean. The plant plays a key role in protecting local water quality in the Cowlitz River watershed, supporting aquatic life and downstream ecosystems in this forested region of the Pacific Northwest.

Toledo STP discharges into a tributary of the Cowlitz River, which flows into the Columbia River and then to the Pacific Ocean. The watershed supports diverse aquatic species, including salmon and steelhead, which are sensitive to nutrient loading and pollutants. The plant's secondary treatment helps reduce organic pollution and protect these ecologically important waterways.