Ilwaco Wastewater Treatment Plant - Ilwaco, Washington | Municipal Wastewater Facility

The Ilwaco Wastewater Treatment Plant is a municipal facility serving the community of Ilwaco, Washington, a small coastal town in Pacific County. With a population served of about 8,127, the plant is classified as a small to medium agglomeration under U.S. regulatory frameworks. The plant's designed capacity is 1.00 million gallons per day, reflecting its role in managing local wastewater flows. As a U.S. facility, the plant operates under the Clean Water Act, administered by the Washington State Department of Ecology through National Pollutant Discharge Elimination System (NPDES) permits. Plants of this scale typically employ secondary treatment to meet federal and state standards for organic and solids removal. The permit ensures compliance with water quality criteria for the receiving water body. The plant's treated effluent is discharged into the Columbia River estuary, a major Pacific Northwest waterway that flows into the Pacific Ocean. This estuary supports diverse aquatic life, including salmon runs and migratory birds. The plant's proximity to the coast (within 50 km) underscores the importance of effective treatment to protect downstream marine and estuarine ecosystems.

The Ilwaco Wastewater Treatment Plant discharges into the Columbia River estuary, which connects to the Pacific Ocean. This estuary is a critical habitat for salmon, steelhead, and other anadromous fish, as well as a stopover for migratory waterfowl. The plant's operations must comply with water quality standards to prevent nutrient loading and pathogen contamination, which could impact shellfish beds and recreational waters in the lower Columbia River and coastal zone.