Intensive Storm Water Monitoring for Metals in the B-Street/Broadway Piers and Downtown Anchorage Drainage Areas of San Diego, CA

Abstract

In this study intensive storm water monitoring was conducted for 22 metals (total and dissolved concentrations) for urban drainage areas in San Diego, CA (B Street/Broadway Piers and Downtown Anchorage) for the period of 2009-2010. Key findings from this monitoring program are presented. Storm water samples were collected during both dry weather periods and wet weather events, and for both sediment and water, at a number of sites (37 dry, 6 wet) across the drainage areas. Wet weather sampling used both pollutagraph and flow-weighted composite sampling to characterize pollutant concentrations during storm events. The land use monitoring sites provide bases for modeling and storm water characterization among different land uses. The results suggested that concentrations of dissolved copper and zinc were elevated compared to hardness-corrected California Toxic Rule (CTR) water quality objectives for both the study areas. Urban and industrial areas were the contributors of total copper and zinc, as suggested by higher concentrations from industrial land use sites. The wet weather sampling suggests there is a relationship between total metals concentrations and flow during storm events but not for dissolved metals. The transport of metals (total concentrations) is facilitated by total suspended sediments (TSS). Estimated daily dry weather loads for a number of metals were greater than wet weather loads, suggesting that dry weather loads can be significant. This study represents one of the most comprehensive efforts at characterizing storm water quality in an urban area.