Spatial and temporal patterns of sewage indicator bacteria in Boston Harbor and its tributary rivers

1. Spatial and temporal patterns of sewage indicator bacteria in Boston Harbor and its tributary rivers Kelly Coughlin Environmental Quality, MWRA

2. 90 sampling stations near CSOs, harbor beaches, treatment plant outfalls, offshore

3. Mass Bay Bacteria Monitoring

4. Overview of bacterial monitoring in Boston Harbor and Mass Bay • CSO Receiving Water Monitoring - ongoing since 1989 - 50 locations in harbor and tributary rivers - 90 surveys per year, 25 station visits per year • Joint MWRA/DCR Harbor Beach Monitoring - ongoing since 1996 (DCR since 1974) - five harbor beaches - ~70 sampling days during swimming season • Mass Bay Bacteria Monitoring - since 1999 - eleven locations in vicinity of outfall - one monthly survey plus adverse surveys

5. Bacterial Indicators Measured by MWRA • Enterococcus measured continuously since 1989 in fresh and marine waters • Fecal coliform in Mass Bay (discontinued for harbor and beach monitoring in 2001, but has resumed for 2008 harbor sampling) • E. coli beginning in 2001, now freshwater only • Enterococcus is required indicator for marine beaches and marine receiving waters (EPA, MADPH, MADEP). • E. coli is required indicator for CSO receiving waters, freshwater • Fecal coliform is required indicator for shellfish growing waters (FDA/MADMF)

6. Dotted line is swimming standard, 33 counts/100 mL Enterococcus Harbor Tributary Rivers ( Note different scale )

7. Dotted line is swimming standard, 35 counts/100 mL Enterococcus Inner Harbor & Embayments

8. Former Harbor Outfalls Before and after closure Pre-closure 1995-1998 Post-closure 1998-2001 Pre-closure 1995-2000 Post-closure 2000-2001 Dotted line is swimming standard, 35 counts/100 mL Enterococcus

9. Wet weather Enterococcus, 1987-1991 1987-1991

10. 1992 - 1998 1992 -1998

11. 1999 - 2007 1999 - 2007

12. Harbor Beach Monitoring MWRA assists Mass. Dept. of Conservation and Recreation (DCR) with daily beach monitoring at four beaches: • Constitution Beach in East Boston • Carson Beach and Pleasure Bay Beach in South Boston • Tenean Beach in Dorchester • Wollaston Beach in Quincy

13. Harbor beach water quality % exceedences of Enterococcus single sample limit at harbor beaches, 1987 - 2007

14. Wet weather impacts on harbor beaches are variable % Enterococcus exceedences at Wollaston, all locations combined

15. Mass Bay Bacteria Monitoring

16. Mass Bay Bacteria Monitoring • 31 of 1179 samples collected since 2000 have exceeded the unrestricted shellfishing standard of 14 counts/100 mL • 2 Enterococcus samples have exceeded the single sample swimming standard of 104 counts/100 mL

17. Summary of Long Term Trends • CSO Receiving Water: dramatic improvements in tributary rivers, less change for locations further from shore; wet weather continues to affect water quality • Harbor Beaches: little improvement in water quality over time, postings primarily triggered by wet weather events • Mass Bay: vast majority of samples meet shellfishing and swimming standards, though exceedences do occasionally occur

18. Acknowledgements • Keary Berger, John Wladkowski, Christopher Dorman, the harbor field team at DITP Central Lab • Laura Ducott, Microbiology, DITP Central Lab