Overview
Pilot Rock STP is a secondary treatment plant serving 1,540 people in Umatilla County, Oregon. It discharges 643.52 thousand cubic meters annually within the Columbia River Basin.
Pilot Rock STP is a municipal wastewater treatment facility located in Umatilla County, Oregon, serving a population of approximately 1,540. The plant provides secondary treatment, a standard level for small communities in the United States, and operates under the regulatory framework of the Clean Water Act, which mandates National Pollutant Discharge Elimination System (NPDES) permits for all discharges to surface waters. The plant has a designed capacity of 946.35 thousand cubic meters per year and currently discharges 643.52 thousand cubic meters annually, indicating operational capacity below design levels. As a secondary treatment facility, it utilizes biological processes to reduce organic matter and suspended solids before discharge, meeting typical requirements for inland plants of this scale. The treated effluent is discharged into a local waterway that ultimately drains into the Columbia River Basin, a major watershed supporting diverse aquatic life and regional agriculture. The plant's location inland and away from coastal areas reduces direct marine impact, but its discharge contributes to the overall water quality management of the basin.
Environmental context
The plant discharges into a tributary of the Columbia River Basin, which flows through Oregon and Washington before reaching the Pacific Ocean. The Columbia River supports critical salmon runs and provides water for irrigation and hydropower. The plant's secondary treatment helps protect downstream water quality, though nutrient and pathogen removal is less comprehensive than tertiary treatment.
Frequently asked questions
Pilot Rock STP is located on Circle Road in Umatilla County, Oregon, United States, serving the community of Pilot Rock.
The plant serves a population of approximately 1,540 people, classifying it as a small community wastewater system.
The plant discharges treated effluent into a local waterway that flows into the Columbia River Basin, ultimately reaching the Pacific Ocean.
Pilot Rock STP provides secondary treatment, which uses biological processes to reduce organic matter and suspended solids, meeting standard requirements for inland plants under the Clean Water Act.
As a US facility, Pilot Rock STP operates under the Clean Water Act, requiring an NPDES permit issued by the Oregon Department of Environmental Quality to regulate its discharge and ensure compliance with water quality standards.
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