Transcript 06_Grenier - San Francisco Estuary Institute

The South Bay Salt Pond
Restoration Project and
Bay Water Quality
SFEI
Letitia Grenier, Jay Davis, Robin Grossinger
South Bay Salt Pond Restoration

Largest tidal wetland restoration project
ever on the west coast
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Comprises 16,500 acres of salt ponds
15,100 acres in South Bay
 1,400 acres in Napa River watershed
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Map from SBSPRP web site
South Bay Salt Pond Restoration
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Extensive geographic scope
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Encompasses much of South Bay shoreline
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Certain to have tremendous benefits
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Concern about water quality
Marshes and Bay Strongly Linked
water
Restored
Marsh
sediment
Bay
food web
Potential for regional impacts
Project Objectives

Mix of wetland habitats for wildlife
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Flood management
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Protect or improve water and sediment
quality
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Public access and recreation
Water Quality Concerns
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Increased mercury in the food web
www.cargillsalt.com
Endangered California Clapper Rail
Methylmercury (MeHg)
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Toxic to animals, including humans
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Accumulates in food webs
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Already a problem in Bay food web
Humans
 Wildlife
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USGS
Human Health Screening Value
Data from Greenfield et al. (2003)
Effects become apparent from 0.5 – 0.8 ppm
Data from Schwarzbach and Adelsbach (2003)
Clapper Rail
Population Trends
See Pulse 2005 for data sources
Increased Food Web Mercury?

Wetlands
Known to produce methylmercury
 New wetlands may produce more MeHg
 Regional effects on MeHg accumulation
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SBSP Restoration Project
Could increase MeHg in food web
 Potentially as important as all current
sources
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Water Quality Concerns
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Increased mercury in the food web
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Legacy sediment pollution
New Almaden Quicksilver Mine
Legacy Sediment Pollution
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Legacy pollutants in Bay marshes, salt
ponds, and their food webs
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PCBs, DDT, Hg
South Bay sources
Historic mercury mining ― New Almaden
 Urban and industrial runoff
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More information is needed
Concentrations 10 times greater than Bay average
Runoff from New Almaden mining district
Beutel and Abu Saba 2004
Water Quality Concerns
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Increased mercury in the food web
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Legacy sediment pollution
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Erosion and recirculation of polluted Bay
sediment
Accelerated Erosion
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Restoration will likely increase erosion of
Bay and marsh sediments in some areas
Increased tidal prism
 Sediment sink
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Buried sediments from the 1950s and
1960s that contain high contaminant
concentrations could be eroded and
relocated
Lower South Bay
Model Prediction
San Pablo Bay Core
Water Quality Concerns
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Increased mercury in the food web
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Legacy sediment pollution
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Erosion and recirculation of polluted Bay
sediment
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Ongoing inputs of pollutants
Ongoing Inputs
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Contaminants
Legacy pollutants (Hg, PCBs, etc.)
 Chemicals in current use (PBDEs, pyrethroids)
 Combustion emissions (PAHs)
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Pathways
Runoff from adjacent watersheds
 Direct atmospheric deposition
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PBDEs
Highest concentration ever observed in biota
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Forster’s Tern egg
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Hayward shoreline
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Near Baumberg
salt ponds
Pyrethroids
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Use increasing in urban areas
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Highly toxic to fish and aquatic
arthropods
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Could cause breakdown of food web as
prey species are affected
How to Address Concerns
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Proceed with restoration
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Adaptive management
Sound science
 Reduce risk
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© C. Benton 2004
Key Recommendations
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Hg monitoring and research should be an
on-going component of the SBSPRP
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Hg poses the greatest contaminant threat to
achieving project goals
Coordination with other research and
monitoring projects (RMP, CBDA)
Further Information
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SBSP Restoration Project
http://www.southbayrestoration.org/
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Article in Pulse of the Estuary 2005 (p.72)
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Davis et al. 2003. San Francisco Estuary and
Watershed Science: Volume 1, Article 4.
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For a longer paper on this topic written for the
SBSPRP, contact me: [email protected]
© C. Benton 2004
© C. Benton 2004