PARENT SESSION
WP5 - Riverine Discharge of Contaminants to Coastal Systems
Chair: Standley, Laurel1, 1 109 I Chestnut Crossing Drive, Newark, DE
2:10 PM to 5:30 PM - Wednesday, 20 November 2002
Room Ballroom D
(608) Discharge of Contaminants from Small Tributaries to San Francisco Bay .
McKee, Lester*,1, Leatherbarrow, Jon1, 1 San Francisco Estuary Institute, Oakland, CA, USA
ABSTRACT- San Francisco Bay is on the Clean Water Act 303(d) list of impaired water bodies for Hg, PCBs, and OC pesticides; PAHs, Cu, and Ni are on the watch list. These contaminants are persistent in the sediments of the Bay and are dominantly transported to the Bay associated with tributary suspended sediment (SS) loads. It is known that the local tributaries that drain the urban and agricultural areas surrounding the Bay have a considerable impact on the water quality, toxicity, and future recovery of the ecosystem. Presently an effort is underway on the best approach to quantify loads entering the Bay from 100s of storm drains. An average of 90% of the discharge of water from local tributaries enters the Bay during the wet season (November to April). Sediment is derived from landslide erosion, streambed and bank erosion, and erosion and transport of urban and agricultural soils and particles. An average of 99% of the SS load enters the Bay during the wet season and loads are highly variable within years and between years. A review of water and sediment transport will be presented in the context of comparisons of methods for estimation of contaminant loads. Using existing data and estimates of contaminant loads as a framework we will demonstrate the design of a new monitoring program to better estimate contaminant loads for TMDL purposes.
Key words: Sediment, Contaminants, Loads, Urban runoff