SILETZ STP - Secondary Wastewater Treatment Plant in Siletz, Oregon

SILETZ STP serves the community of Siletz, Oregon, a small town in Lincoln County. The plant treats wastewater for a population of 1,197, operating under the regulatory framework of the U.S. Clean Water Act, which requires secondary treatment for municipal facilities of this scale. The plant has a designed capacity of 1,400.60 cubic meters per day and currently discharges 794.94 cubic meters per day, indicating operational headroom. As a secondary treatment facility, it uses biological processes to reduce organic pollutants and suspended solids before discharge. The treated effluent is released into local waterways that drain toward the Pacific Ocean. The plant plays a key role in protecting the Siletz River and downstream ecosystems, including coastal habitats that support salmon and other aquatic species.

The plant discharges into the Siletz River watershed, which flows westward through the Oregon Coast Range and empties into the Pacific Ocean near Siletz Bay. This coastal estuary supports diverse aquatic life, including salmon runs and migratory birds. The plant's secondary treatment helps maintain water quality in this ecologically sensitive region.