Tamoshan WWTP, Olympia, Washington - Secondary Treatment Plant

Tamoshan WWTP is a municipal wastewater treatment facility located in Olympia, Washington, United States. It serves a small population of 292 residents, reflecting its role in a rural or suburban area of Thurston County. The plant is situated near Glenwood Drive Southwest, within the Pacific Northwest region known for its temperate climate and abundant water resources. The plant provides secondary treatment, a standard biological process that removes organic matter and suspended solids. With a designed capacity of 189.27 cubic meters per day and a discharge volume matching that figure, the facility operates at full capacity. As a US plant, it falls under the Clean Water Act and is likely regulated by an NPDES permit issued by the Washington State Department of Ecology, which sets effluent limits to protect water quality. The treated effluent is discharged into a local water body that ultimately drains to the Puget Sound, a major estuary of the Pacific Ocean. This coastal discharge location means the plant's operations are critical for protecting marine ecosystems, including shellfish beds and salmon habitats that are ecologically and economically significant to the region.

The plant discharges into a tributary of the Puget Sound, a large estuarine system connected to the Pacific Ocean. The Puget Sound supports diverse marine life, including salmon, orcas, and shellfish, and is a vital ecological and economic resource. Secondary treatment helps reduce nutrient and pollutant loads, but coastal discharge requires careful management to prevent eutrophication and protect sensitive nearshore habitats.