In Pursuit of Urban Runoff in an In Pursuit of Urban Runoff in an Urbanized Estuary:Urbanized Estuary:

“Losing sleep over troubled water”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!

Where do all the PCBs come from?

Where does the mercury come from?

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

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Rainfall90% 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

Sampling28% 51%

In Other Words - Sampling Mirrors Runoff!

The Hydrograph in More Detail

LowerWatershedPeak

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Peak

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Preliminary data

Inter-annual variations

Mercury (ug/l) PCBs (ng/L)Minimum Maximun Minimum Maximun

Water Year 2003 0.2 18.7 3.4 90Water Year 2004 MDL 1.4 0.9 67

Mercury (kg) PCBs (kg)

Water Year 2003 312 82 1.1± 0.3Water Year 2004 <60 ~0.5 (Questimate)

Preliminary data

Extrapolating the WY 2003 PCB result yields about 25 kg (notdissimilar 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