inner cabrillo beach source tracking study and quantitative … · 2019-03-07 · birds were a...
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Inner Cabrillo BeachSource Tracking Study
AndQuantitative Microbial Risk
Assessment (QMRA)
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Background
• The issue: Not all FIB come from human sources- non-human sources are less “risky”
• The option: EPA identified QMRA as a tool for Site-Specific Objectives
- New objectives based on health risk
• The challenge: QMRA for Site-Specific Objectives has never been done at a marine beach
• The goal: Conduct a QMRA at a marine beach in California- Use as a precedent setting case study
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QMRA Framework
• Source identification- Goal is to know sources for sampling pathogens
• Pathogen loading- To generate exposure information
• Risk modeling- Sensitivity testing
• Advisory Committee- Regulatory, regulated, NGO
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Inner Cabrillo Beach Met the 8 Criteria
• Persistent, but low level FIB exceedances• High level of effort to eliminate human sources• Willing Partners• High volume of beach use• Total Maximum Daily Load (TMDL) completed/Adopted• Septic tanks are minimal and not a prominent sewage
treatment solution• Implemented dry weather flow diversions• Well defined, small watershed
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The Final Outcome
• Birds were a major source of Enterococci at ICB
• There was a persistent, but low level of human fecal contamination at ICB based on HF183
- Attempts to fix beach sewage infrastructure did not get rid of the HF183
• The QMRA has been placed on hold
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Sampling Sites at Cabrillo Beach (2016)
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Site
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uman
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Ent M
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Enterococcus, Gull Marker and Human Marker Concentrations at Cabrillo Beach (2016)
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Human Marker Concentrations In Outer Los Angeles Harbor (2017)
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Human Marker Concentrations In Outer Los Angeles Harbor (2017)
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Human Marker Detection Frequency BeforeSewage Collection System Repairs (2016) Compared to After Repairs (2018)
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The Final Outcome
• Birds were a major source of Enterococci at ICB
• There was a persistent, but low level of human fecal contamination at ICB based on HF183
- Attempts to fix beach sewage infrastructure did not get rid of the HF183
• The QMRA has been placed on hold
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Some Potential Next Steps
• Identify the human source or pathway for pathogen loading
- Groundwater is the next logical choice
• Conduct low-level pathogen analysis in receiving waters- Will require substantial method development