Do you know where your drinking water comes from?

1. Do you know where your drinking water comes from? An overview of hydrogeology and health Jean M. Bahr University of Wisconsin - Madison

2. Sometimes the sources are obvious

3. Sometimes the storage systems are obvious, but the sources are not

4. Residence time – 11 days decades to 1000s of yrs 1000 to >10,000 yrs weeks to decades Reservoirs of fresh water on Earth The hydrologic cycle Reservoir % Fresh % Unfrozen Atmosphere 0.04 0.2 Ice 73.9 --- Lakes + Streams 0.36 1.4 Ground water 25.7 98.4

5. Two main sources: ground water and surface water 37% 63% Water used in the US in 2000 for public domestic supply (serves 85% of population) Figures from USGS Circular 1268 http://pubs.usgs.gov/circ/2004/circ1268/

6. Self supply for remaining 15% of population (almost entirely ground water) Figure from USGS Circular 1268

7. Northfield Minnesota is supplied by 4 wells with depths ranging from 365 to 410 feet – so YOU are drinking ground water http://www.ci.northfield.mn.us/cityhall/departments/publicworks/water

8. Some Ground Water Basics

9. Common misconceptions about ground water

10. Micropores in sandstones and carbonates Virtually no pores in granite Macropores in limestone, basalt, crystalline rocks Ground water is primarily water held in “pores”

11. Major types of geologic materials and associated porosity Sandstone and carbonate Volcanic rocks (basalt) Unconsolidated sediment Carbonate rocks (e.g. limestone) Fractured igneous and metamorphic rocks

12. Extent and thickness of the Jordan Sandstone

13. Zones of Subsurface Water Soil water in the Unsaturated Zone (air and water in pores) Ground water below the “water table” (in the Saturated Zone)

14. Some Water Quality Basics

15. Health-based standards for drinking water quality

16. Non-enforceable “Secondary Standards” based on cosmetic and aesthetic effects

17. Acidic Neutral Basic Another important property pH: a measure of hydrogen ions in solution, commonly referred to as “acidity”

18. Trout TDS – wide range pH 6-5-8.0 Hardness 10-400 Oxygen >5 ppm Temp. optimum 50-60oF Human Drinking Water TDS < 500 ppm pH 6-5-8.5 Chloride < 250 ppm Sulfate < 250 ppm Iron < 0.3 ppm Dairy Cows TDS < 4000 ppm pH 6-5-8.5 Chloride < 1600 ppm Comparison of drinking water and other standards

19. What do we find dissolved in ground water?

20. Precipitation chemistry controlled by interaction with the atmosphere Earth’s atmosphere • Resulting water composition • Dissolved nitrogen • Dissolved oxygen • Dissolved carbon dioxide • carbonic acid • pH around 5

21. Water entering the saturated zone has low pH, enhancing mineral dissolution, and may be “reducing” (low dissolved oxygen), which can enhance solubility of trace metals pH of infiltrating water is further altered in the unsaturated zone Microbial degradation of organic carbon consumes dissolved oxygen and produces CO2

22. Continued chemical evolution along ground water flow paths

23. Ground water composition reflects abundance of elements in geologic materials mineral solubility

24. Saline ground water in coastal areas or in deep basin “brines”

25. Examples of naturally occurring constituents with health effects • Fluoride • Arsenic • Radium and radon • Water “hardness” • Naturally occurring organics

26. Combined effects of poor nutrition and excess F Effects of fluoride deficiency and excess

27. Understanding of the fluorine cycle aids in anticipating F concentrations in ground water

28. Areas of high F in Arizona and California associated with extensional basins

29. Arsenic poisoning in Bangladesh

30. Arsenic in Minnesota and Wisconsin Wells Source: MPCA Ground Water Monitoring and Assessment Program Source: Wisconsin Dept. of Nat. Resources

31. Ground water use lowers water table and exposes sulfide minerals to oxygen O2 O2 Arsenic in Wisconsin’s Fox Valley Arsenic bearing sulfide minerals at the top of the St. Peter Sandstone

32. Pumping in the Fox Valley and near Green Bay has lowered the water table and introduced oxygen to the aquifer The City of Green Bay now uses Lake Michigan water delivered by a pipeline

33. Proposal to use ASR (aquifer storage recovery) as an alternative to surface reservoirs

34. shallow medium deep Monitoring intervals Green Bay Well 10 Borehole flowmeter logging to identify possible preferential flow zones

35. Arsenic concentrations during storage phase of Green Bay pilot test

36. Arsenic concentrations during recovery phase of Green pilot test

37. Lower, but still problematic, concentrations of arsenic found in ground water from glacial deposits and shallow bedrock of SE Wisconsin Health effects of chronic exposure to low concentrations are not well established

38. Tara Root Core hole at Woods School near Lake Geneva WI

39. Measurable, but not dramatically high, concentrations of arsenic through most of the core below upper sand and gravel

40. Sampling, field and laboratory analyses from private wells

41. Arsenic released from iron oxides where oxygen is depleted – below the Foxhollow Till

42. Products of uranium decay

43. Radon and radium in WI ground water associated with trace concentrations of uranium in the St. Peter Sandstone From USGS Circular 1156

44. Calcium + magnesium concentrations:“hardness” Hard water “stops heart attacks” Drinking hard water may protect against heart disease, researchers have claimed. Researchers from the Geographical Survey of Finland looked at 19,000 men who had suffered heart attacks. They found for every unit increase in water hardness, there was a 1% decrease in the risk of having a further attack. Writing in the Journal of Epidemiology and Community Health, the researchers said the findings explained regional variations in heart attack rates.

45. BEN Areas Lignite mine in affected area Correlation between natural organics in drinking water and Balkan endemic nephropathy (kidney disease) High nitrate concentrations also occur in ground water of the affected area

46. Anthropogenic contaminants from “point” and “non-point” sources

47. Non-point human, animal and agricultural sources of nitrate

48. Point sources generate a contaminant “plume” TCE plume, 1992 Eau Claire Well Field

49. Large plumes from small sources

50. Some contaminants are “retarded” by interactions with aquifer solids Retarded transport of contaminants that adsorb to aquifer solids A “conservative” contaminant Slower migration of plumes, but also slower removal by pumping