In 1987 the Clean Water Act (CWA) was amended to address non-point sources through the National Pollutant Discharge Elimination System (NPDES) program, which was divided into Phase I and Phase II. Washington State Department of Transportation (WSDOT) is a NPDES Phase I permit applicant, which requires them to monitor their facilities for specific water quality parameters. Effective and affordable treatment of highway runoff is a significant concern, because various pollutants found in non-point source runoff can impact the overall health of a watershed. Furthermore, many factors influence the types and concentrations of pollutants found in stormwater and the various types of Best Management Practices (BMP) available. Stormwater regulations utilize a prescriptive approach, which assumes that water quality standards will be met if on-site BMPs are implemented. This methodology does not consider what the watershed concerns are and how the BMP will protect aquatic resources or declining salmon populations. Furthermore environmental agencies take a perspective approach which views the environment as a cause and effect relationship this approach creates barriers to new innovative ideas and off site mitigation. Often the regulator evaluates the impacts and mitigation in the project limits versus considering offsite mitigation which could benefit the watershed and reduce project costs. This paper will evaluate: • What are the water quality concerns for the watershed? • What level of performance do BMPs achieve? 6 • Is the BMP effective in addressing water quality concerns in the watershed? I will further illustrate the dilemma for two WSDOT stormwater sites with on-site stormwater mitigation with approved BMPs versus considering off-site mitigation or experimental BMPs. Furthermore, we are left without a clear understanding of why concentrations of pollutants vary between storm events and sites and which types of BMPs are required to meet legislated performance goals that have been set across the board, in a cost-effective manner on site.
stormwater, highway runoff, Best Management Practices
Weber, Sherry L.. "Evaluation of Two Washington State Department of Transportation Stormwater Facilities along State Route 18 Highway." (2007). https://digitalrepository.unm.edu/wr_sp/74