Mckee, L.; Gilbreath, A.; Sabin, L. 2022. Small Tributaries Pollutants of Concern Reconnaissance Monitoring: Application of Storm-event Loads and Yields-Based and Congener-Based PCB Site Prioritization Methodologies. SFEI Contribution No. 1067.

Stormwater agencies in the San Francisco Bay Area are identifying watershed areas that are polluted with PCBs in order to prioritize management efforts to reduce impairment in the Bay caused by PCBs carried in stormwater. Water sampling during storms has been used to characterize PCB concentrations but management prioritization based on the comparison of concentrations between watersheds is made difficult due to variations in flow and sediment erosion between storms and in relation to varying land use. In addition, identifying PCB source areas within priority watersheds has proven complex and costly. To address these challenges, the San Francisco Bay Regional Monitoring Program (RMP) has developed two new interpretive methods based on storm-event PCB yields (PCBs mass per unit area per unit time) and fingerprints of Aroclors (commercial PCB mixtures) that make existing data more useful for decision-making. 

The objectives of this study were to: 

  • Apply the yield method to the regional stormwater dataset and provide new rankings, 
  • Estimate the presence of Aroclors in samples where congener data are available
  • Evaluate data weaknesses and recommend watersheds to resample, and
  • Classify watersheds into high, medium, and low categories for potential management.