College Place WWTP - Walla Walla County, Washington Wastewater Treatment Plant

College Place WWTP is a municipal wastewater treatment facility located in Walla Walla County, Washington, serving a population of about 8,780. The plant is situated inland, away from coastal areas, and discharges treated effluent into local waterways that ultimately drain into the Columbia River basin. As a US facility, the plant operates under the Clean Water Act and is subject to National Pollutant Discharge Elimination System (NPDES) permits issued by the Washington State Department of Ecology. For a plant serving this population size, secondary treatment is the standard requirement, ensuring removal of organic matter and suspended solids before discharge. The treated wastewater from College Place WWTP enters the local watershed, which flows into the Walla Walla River and eventually the Columbia River. This region supports diverse aquatic life, including salmonid species, and the plant's treatment processes help protect water quality in these ecologically important waterways.

The plant's discharge enters the Walla Walla River, a tributary of the Columbia River, which flows to the Pacific Ocean. The watershed supports critical habitat for salmon and steelhead, making effective wastewater treatment essential for maintaining water quality and ecosystem health in this agriculturally influenced region.