NPDES Program

The National Pollution Discharge Elimination System (NPDES) program is a congressionally mandated program under the Clean Water Act. The program is a comprehensive two-phased national program for addressing the non-agricultural sources of storm water discharges that adversely affect water quality. The program is implemented locally through the Oregon Department of Environmental Quality (DEQ). DEQ issues permits to applicable entities which participate in and/or oversee activities which are recognized as potential sources of pollutants. Municipal Separate Storm Sewers Systems (MS4), Industrial Activities and Construction Activities all potentially require an NPDES permit.

The City of West Linn obtained a permit under Phase 1 of the NPDES program in 1995. The City operates under a MS4 system which means that all storm water is collected and conveyed in a storm sewer system separate from the sanitary sewer system. Under Phase 1 of the federal program only MS4 systems serving a population of 100,000 or larger were required to obtain a permit. Although this City of West Linn was not subject to Phase 1 requirements, the City of West Linn took a progressive stance towards water quality and chose to comply with the NPDES permit as a co-applicant of Clackamas County.

As part of the permit the City has developed a Storm Water Management Plan that outlines Best Management Practices (BMPs) that the City will implement to improve and conserve water quality, as well as, prevent harmful pollutants from contaminating storm water runoff and entering the MS4. The nuts and bolts of this program include identification of major outfalls and estimating pollutant loadings; detecting and eliminating non-storm water discharges to the MS4; reduction of pollutants in runoff from industrial, commercial and residential areas; control storm water discharges from new development & redevelopment and regular maintenance of the public storm water collection/ treatments systems.

Compliance is essentially achieved by implementing an approved Storm Water Management Plan. Each permit holder is required to report annually the procedures, tasks and best management practices achieved that benefit water quality.