Colton STP - Secondary Wastewater Treatment Plant in Colton, Washington

Colton STP is a municipal wastewater treatment facility located in Colton, Whitman County, Washington, United States. The plant serves a small population of 395 residents, reflecting the rural character of the community. It operates as a secondary treatment plant, a standard level for small agglomerations under U.S. regulations. The plant's designed capacity is 280.12 megaliters, with an annual discharge volume of 227.13 megaliters, indicating moderate utilization. Under the U.S. Clean Water Act, such facilities are typically regulated through National Pollutant Discharge Elimination System (NPDES) permits issued by the Washington State Department of Ecology, ensuring compliance with water quality standards. The treated effluent is discharged into a local water body that ultimately drains into the Snake River basin, a major tributary of the Columbia River. The Columbia River system supports diverse aquatic life, including salmon runs, and flows to the Pacific Ocean. The plant's operations contribute to protecting downstream water quality in this ecologically significant watershed.

Colton STP discharges into a local watercourse that flows into the Snake River, a key tributary of the Columbia River. The Columbia River basin supports critical salmon and steelhead habitats and is an important migratory corridor for fish. The plant's secondary treatment helps reduce nutrient and organic loads, protecting downstream water quality in this ecologically sensitive region.