Langley S_T Facility Wastewater Treatment Plant, Langley, Washington

The Langley S_T Facility is a municipal wastewater treatment plant located on Coles Road in Langley, Washington, on Whidbey Island in Island County. The plant serves a small population of 1,045 residents, reflecting the rural and coastal character of the community. The plant provides secondary treatment, which is the standard level required under the U.S. Clean Water Act for municipal wastewater. The facility has a designed capacity of 567.81 megaliters per year and currently discharges 302.83 megaliters annually. As a small coastal plant, it operates under the National Pollutant Discharge Elimination System (NPDES) permit program, administered by the Washington State Department of Ecology, which sets effluent limits to protect receiving waters. The plant's treated effluent is discharged into the waters of Puget Sound, a major estuary of the Pacific Ocean. Puget Sound supports diverse marine life, including salmon, orcas, and shellfish, and is ecologically sensitive to nutrient and pollutant inputs. The facility plays a key role in protecting this vital ecosystem from untreated wastewater.

The Langley S_T Facility discharges into Puget Sound, a large estuary connected to the Pacific Ocean via the Strait of Juan de Fuca. Puget Sound is a critical habitat for salmon, forage fish, and marine mammals, and is subject to nutrient management concerns. The plant's coastal location means its discharge directly influences nearshore water quality and marine life.