Characterization of Stormwater Transport of Contaminants of Emerging Concern

The City of Tacoma, in partnership with Western Washington collaborators, will characterize stormwater and stormwater sediment concentrations for several Contaminants of Emerging Concern (CEC). They will study 15 sites associated with four land uses: Industrial, Commercial, High Density Residential, and Low Density Residential.

Previously, permittees monitored stormwater from these land uses as required by the Municipal Phase I permit. The immense data set has been used in several planning tools including The Nature Conservancy’s Stormwater Heatmap, King County’s Water Quality Benefits Evaluation toolkit, Seattle’s Integrated Plan, and Tacoma’s Watershed Insights Tool.

In this follow up project, Tacoma will coordinate sample collection at 16 sites. Stormwater and stormwater sediment samples will be analyzed for 6PPD-quinone, vehicle-derived constituents, PFAS, tire and road wear particles (TRWP), and microplastics. Additionally, they will analyze for the same chemistry parameters collected from many of the same locations over a decade ago to enhance our understanding of stormwater quality trends.


Study questions

  • What is the correlation between different land uses (industrial, commercial, residential) and the concentrations of emerging contaminants in stormwater?
  • Has stormwater quality improved over the past decade, as indicated by samples collected from the same locations during different time periods?

Study findings

This project will continue through 2027.

Project tasks & key deliverables

Contract & Scope of Work

  1. Project management
    • Technical Advisory Committee meeting notes
    • Semi-annual progress reports
  2. Plan for monitoring
    • GIS analysis for each basin
    • Equipment purchasing
    • Quality Assurance Project Plan
  3. Review CEC literature and available data
    • Database of existing CEC data and associated land use
    • Literature review
  4. Sample collection and monitoring
    • Site installation
    • Field notes from each collection event
    • Laboratory reports
  5. Data management and analysis
    • Quality assurance review of data
    • Internal technical dashboard
    • External communications dashboard
  6. Communication Plan and reporting
    • Communication Plan and Project Schedule
    • Project Report
    • Data submitted to Ecology’s Environmental Information Management database
    • Three presentations, including one to Stormwater Work Group
    • SAM Fact Sheet