Tonasket S_T Facility - Wastewater Treatment Plant in Tonasket, Washington

The Tonasket S_T Facility is a municipal wastewater treatment plant located in Tonasket, Okanogan County, Washington, United States. It serves a small population of approximately 1,025 residents, reflecting the rural character of the region. The plant is situated along Railroad Avenue, near the Okanogan River. The facility provides secondary treatment, which is the standard level required under the U.S. Clean Water Act for municipal wastewater. Secondary treatment typically involves biological processes to reduce organic matter and suspended solids. The plant has a designed capacity of 946.35 m³/day and currently discharges 757.08 m³/day, indicating it operates below its full capacity. The treated effluent is discharged into the Okanogan River, a tributary of the Columbia River. The Columbia River basin supports diverse aquatic life, including salmon and steelhead, and is a critical water resource for the Pacific Northwest. The plant's discharge is regulated under the National Pollutant Discharge Elimination System (NPDES) permit program to protect water quality.

The plant discharges into the Okanogan River, which flows into the Columbia River, ultimately reaching the Pacific Ocean. The Columbia River basin is ecologically significant, supporting salmon runs and other native fish species. The region's semi-arid climate and agricultural land use make water quality management important for both ecological health and human use.