Overview
Mossyrock S_T Facility is a secondary wastewater treatment plant in Lewis County, Washington, serving a small population of 533. It discharges treated effluent into the local watershed, supporting downstream water quality.
Mossyrock S_T Facility is a municipal wastewater treatment plant located in Lewis County, Washington, United States. It serves a small community of 533 residents, reflecting its role as a local infrastructure asset in a rural area of the Pacific Northwest. The plant provides secondary treatment, a standard biological process that removes organic matter and suspended solids. With a designed capacity of 454.25 volume units and a current discharge volume of 264.98, the facility operates under the regulatory framework of the U.S. Clean Water Act, which requires National Pollutant Discharge Elimination System (NPDES) permits for all point-source discharges. For plants of this scale, state-level permits typically set effluent limits to protect receiving waters. The treated wastewater is discharged into a nearby water body that drains into the Cowlitz River basin, eventually reaching the Columbia River and the Pacific Ocean. This connection underscores the plant's role in safeguarding regional water quality and aquatic habitats in the broader Columbia River watershed.
Environmental context
The plant discharges into a local stream that flows into the Cowlitz River, a major tributary of the Columbia River. The Columbia River system supports diverse aquatic life, including salmon and steelhead runs, and is an important ecological corridor in the Pacific Northwest. The facility's secondary treatment helps reduce nutrient and pollutant loads, protecting downstream water quality in this sensitive river basin.
Frequently asked questions
Mossyrock S_T Facility is located in Lewis County, Washington, United States, near the town of Mossyrock in the Pacific Northwest region.
The plant serves a small population of 533 residents, typical of a rural community wastewater system in Washington state.
The plant discharges treated effluent into a local water body that flows into the Cowlitz River, part of the Columbia River basin, ultimately reaching the Pacific Ocean.
As a U.S. facility, it operates under the Clean Water Act, requiring an NPDES permit issued by the Washington State Department of Ecology, which sets effluent limits to protect water quality.
For small communities, secondary treatment is standard, providing biological removal of organic matter and suspended solids to meet federal and state discharge standards.
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