Rock Island WWTP - Projected Secondary Treatment Plant in Washington

Rock Island WWTP is a planned wastewater treatment facility located in Rock Island, Douglas County, Washington. Designed to serve a population of 1,075, the plant will provide secondary treatment for the community's municipal wastewater. As a projected facility, it represents future infrastructure development for the area. The plant will employ secondary treatment, a standard biological process that removes organic matter and suspended solids. With a designed capacity of 851.72 volume units, the facility is sized to meet the needs of the small population. Under the U.S. Clean Water Act, such plants must obtain National Pollutant Discharge Elimination System (NPDES) permits from the Washington State Department of Ecology, ensuring compliance with water quality standards. The treated effluent will be discharged into the Columbia River basin, which ultimately drains to the Pacific Ocean. The receiving waters support diverse aquatic life, including salmon runs, and the plant's operation will help protect downstream water quality and ecological health.

The plant discharges into the Columbia River basin, a major watershed that flows through Washington and Oregon to the Pacific Ocean. This river system supports critical habitats for salmon, steelhead, and other native species. The secondary treatment process will reduce pollutants, helping to maintain water quality in the basin and protect downstream ecosystems.