Pomeroy WWTP - Secondary Treatment Plant in Pomeroy, Washington

Pomeroy WWTP is a municipal wastewater treatment facility located in Pomeroy, Garfield County, Washington. The plant serves a population of approximately 1,425 residents, classifying it as a small-scale facility under U.S. EPA guidelines. It is situated inland, away from coastal influences, and treats wastewater from the local community. The plant provides secondary treatment, a standard level required by the Clean Water Act for most municipal facilities in the United States. With a designed capacity of 1,022.06 million gallons per day and an average discharge volume of 764.65 million gallons per day, the plant operates below its capacity, indicating room for future growth. The facility is permitted under the National Pollutant Discharge Elimination System (NPDES), which sets effluent limits to protect water quality. Treated effluent from Pomeroy WWTP is discharged into a local water body that drains into the Snake River basin, part of the larger Columbia River watershed. This region supports diverse aquatic life and is important for regional agriculture and recreation. The plant's operations help maintain the ecological health of downstream waters by reducing pollutant loads.

The plant discharges into a tributary of the Snake River, which flows into the Columbia River and eventually reaches the Pacific Ocean. The local watershed supports salmonid species and other aquatic life, making water quality protection critical. The plant's secondary treatment helps reduce organic pollutants and suspended solids, mitigating impacts on downstream ecosystems.