Road salting practices in Suffolk County, New York are negatively impacting local groundwater quality. Analysis of bromide and chloride levels found elevated ratios consistent with road salt intrusion near highways. Two wellfields showed clear evidence of saltwater or road salt contamination through changing bromide-chloride ratios over time. Potential solutions like improved drainage systems or reducing road salt usage could help but have not been implemented due to high costs.

1. The Effects of Road Salting on Groundwater Quality at Public Supply Wellfields, Suffolk County, New York Tyrand T. Fuller Suffolk County Water Authority

2. LONG ISLAND Atlantic Ocean Long Island Sound NYC North Fork South Fork Suffolk County

3. -All Recharge from precipitation -Total Precipitation 45 inch/year of which 30 inches snow

6. Example of Lateral Encroachment in Well

7. Example of Saltwater Upconing in Well

8. South Fork

9. South Fork

10. Block Island Sound Atlantic Ocean

11. North Fork

12. North Fork

13. State Route 25 Long Island Sound

14. Bromide Chemistry -Ocean is the largest reservoir of Br -Br/Cl Molar Ratio is 1.54 nM/uM (Constant in both Freshwater and Seawater) -Road Salt causes ratio to -Pesticides causes ratio to

15. Chlorides -ppm Example of Saltwater Upconing in Well

24. Mill Lane Profile Overview High Chlorides High Chlorides High Chlorides High Chlorides Profile 2 Profile 1 Profile 3

25. Br/Cl Molar Ratio of Mill Lane Vertical Profiles

27. High Chlorides

28. Low Br/Cl Ratio

29. Br/Cl Ratio in Seawater/Freshwater

30. Br/Cl Ratio in Seawater/Freshwater

31. Br/Cl Ratio in Seawater/Freshwater

32. Br/Cl Ratio in Seawater/Freshwater

33. Possible solutions -Reconfigure highway drainage systems -Low capacity blocking wells -Altering road salting practices (Calcium Chloride, less road salt) -Methods have not yet been implemented due to high costs

34. Conclusion -Br/Cl molar ratio analysis is effective in determining waters impacted by either seawater or road salt -Ackerly Pond and Mill Lane both indicate that wells are impacted by Road Salting

35. Acknowledgements Joseph Pokorny, Steve Colabufo, Richard Bova (SCWA) Fred Stumm, Tony Chu, Craig Brown (USGS)