Presentation on theme: "In Pursuit of Urban Runoff in an Urbanized Estuary: Losing sleep over troubled water In Pursuit of Urban Runoff in an Urbanized Estuary:Losing sleep over."— Presentation transcript:
In Pursuit of Urban Runoff in an Urbanized Estuary: Losing sleep over troubled water In Pursuit of Urban Runoff in an Urbanized Estuary:Losing sleep over troubled water Lester McKee, Ph.D. Sources Pathways and Loading Workgroup
What is all the fuss over? Urbanized portions of the Bay Area watersheds are significant sources of persistent contaminants (PCBs, mercury, OC pesticides, dioxins, and PBDEs). For example, urban runoff likely accounts for ~41% of the annual 83 kg PCB load (Hetzel 2004). The TMDLs for PCBs and mercury propose large reductions in urban runoff loads. Sound science on loads monitoring and research into urban BMP performance are essential ingredients in adaptive implementations of the TMDLs. Troubled waters!
How long has all this been happening? 1800 1900 1850 2000 1950 1840s: Hg discovered in Guadalupe River watershed 1870s: Hg production reached a maximum 1929: PCBs first manufactured 1940s: OC pesticides first used in CA 1972: DDT banned 1979: PCBs banned 1980s: Chlordane and dieldrin banned TMDLs
The Challenge of Measuring Loads in Urban Runoff Rainfall 90% falls in the winter Varies from 40-200% of the average
The Guadalupe River Study (Funding from CEP and RMP)
Objectives To determine if urban runoff from small tributaries such as Guadalupe River are significant sources of PCBs, mercury and OC pesticides To measure concentrations over floods and between years to get a better understanding of how contaminants are transported from sources under variety of climatic conditions Provide a reliable data set to evaluate the effectiveness of management To inform the debate on how best to improve water quality in the Estuary
The Hydrograph in More Detail Lower Watershed Peak Upper Watershed Peak
Upper versus lower (urbanized) watershed concentrations PCBs Mercury Lower Upper Preliminary data
Inter-annual variations Preliminary data Extrapolating the WY 2003 PCB result yields about 25 kg (not dissimilar to the TMDL report estimate).
What can be done about stormwater loads? Both the PCB and mercury TMDL reports promote urban BMPs as a potential solution for reducing loads. BMP Issues -Stormwater BMPs such as street sweeping and stormwater maintenance programs have been in place for a long time – how much more is feasible? -Most BMPs capture sediment to a measurable degree but which BMPs improve effluent quality of trace contaminants the most? -What is the best way to measure BMP effectiveness and which combination of BMPs will be likely most effective in the Bay Area urban landscape?
BMPs and Prop 13 Feasibility of capture of urban pollutants is the subject of several recent stormwater agency studies and a CEP study led by LFR. In addition SFEI is collaborating with BASMAA and the Regional Board on a Prop 13 grant titled: Regional Stormwater Monitoring and Urban BMP Evaluation: A Stakeholder-Driven Partnership to Reduce Contaminant Loadings
By 2007 An almost complete map of >24 inch storm drains for the Bay Area A model that either supports or rejects the use of suspended sediment data for extrapolation of more limited contaminant data to unmonitored watersheds An evaluation of loads of priority contaminant avoided by urban stormwater BMPs An evaluation of up to 4 BMPs in common use in the Bay Area for efficiency in effluent concentration reductions
Acknowledgements Sources Pathways and Loadings Workgroup SFEI field team – Nicole David, Ben Greenfield, Jennifer Hunt, Sarah Pearce, Linda Russio, Seth Shonkoff, Chuck Striplen, Eric Wittner, and Don Yee Collaborators – Rand Eads (RSL), Larry Freeman (USGS), Russ Flegal (UCSC) Laboratories – MLML, AMS (Texas), AXYS