Groundwater in the Great Lakes Basin

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Recommended Future Research Geologic and hydrogeologic mapping of principal aquifers needs to continue to determine regional variability of rocks and glacial deposits as well as the hydraulic properties of these aquifers and confining units. Mapping will help determine the local and regional impacts of groundwater flow on surface water bodies and the ecological implications of changes in groundwater input to streams. Specifically, previous work on geologic mapping of glacial deposits by the state and provincial surveys in conjunction with the Geological Survey of Canada and USGS needs to be enhanced. Estimation of Natural Groundwater Recharge Recent Research Better estimates of the rates of groundwater recharge are needed in order to understand the importance of groundwater resources in the basin. Several estimates of groundwater recharge in parts of the basin have been reported (Holtschlag, 1996; Cherkhauer, 2001; Dumouchelle and Schiefer, 2002; Wolock, 2003; Gebert, Radloff, Considine and Kennedy, 2007; Delin and Risser, 2007; Delin, Healy, Lorenz and Nimmo, 2007. From a basinwide perspective, however, the first known integrated study of long-term average groundwater recharge to shallow aquifers on both the Canadian and U.S. portions of the basin was presented by Neff, Piggott and Sheets (2005), who used streamflow separation and assumed that baseflow of a stream originated as groundwater recharge. By using empirical relations between baseflow characteristics and surficial geologic materials, they concluded that the highest shallow groundwater recharge rates occurred in snow shadow areas east and southeast of each Great Lake. The lowest recharge rates occurred in the eastern Lower Peninsula of Michigan, southwest of Green Bay, near the southwestern shore of Lake Erie, in portions of southeast Ontario and west of Toronto (Neff et al., 2005). Methods to estimate recharge rates are summarized in Delin and Risser (2007). Recommended Future Research Neff et al. (2005) suggested that alternative methods that do not rely on indirect estimation of recharge by baseflow analysis could be used to determine the spatial and temporal scale of recharge. Gebert et al. (2007) used some of these alternative methods on a smaller sub-basin scale; these could be transferred to the larger, basin-wide scale. Long-term effects of anthropogenic activities and global climate change on recharge also could be investigated. Using precipitation as input for recharge estimates will make the predicted rates of recharge under climate change more reliable than using baseflow as input. The relations between groundwater recharge and development (both urban and agricultural) also need to be researched more thoroughly. Urban development covers part of the land surface with pavement and building materials that may cause less water from precipitation to infiltrate the land surface and recharge the groundwater system. Similarly, the effects of tile drainage on recharge in agricultural areas also need to be more thoroughly researched. Studies to quantify the effects of development on recharge have not been conducted other than a few studies that show the effects of urban and agricultural development on baseflow of streams. Groundwater Discharge to Surface Water Recent Research Streams interact with groundwater in three ways: They gain water from inflow of groundwater through the streambed, they lose water to groundwater by outflow through the streambed, and both, gaining in some reaches and losing in others (Winter, Harvey, Franke and Alley, 1998). In the humid Great Lakes Basin, many more streams gain water from groundwater discharge than lose water. In recent years, the relation between groundwater flow and stream flow has been more carefully determined mainly by using various baseflow separation techniques and groundwater flow models. Holtschlag and Nicholas (1998) published a spatially limited baseflow separation study which covered approximately 14% of the basin. A more comprehensive basinwide analysis of baseflow was published by Neff, Day, Piggott and Fuller (2005), which incorporated analysis of baseflow on both the U.S. and Canadian sides of the border. Groundwater issues in the region are related to the fact that the international border runs through the Great Lakes. Therefore, exploitative use of groundwater on one side of the border automatically has effects on the other side because it changes the amount of water flowing to the Great Lakes. At this time, groundwater withdrawals have not had any measurable impact on Great Lakes water levels. Groundwater discharge to streams can be better understood if the changes in stream flow over longer intervals are better known. To help interpret long-term changes, Hodgkins, Dudley and Aichele (2007) analyzed both the mean annual and the 7-day low-flow runoff in the basin. These two summary statistics are related to the changes in groundwater discharge to streams. Using a network of stream flow gages with long-term records 17
that are not substantially affected by regulation, Hodgkins et al. (2007) determined that mean annual runoff increased by 2.6 inches from 1955 to 2004. The increases were fairly consistent throughout the basin, with the only decreases occurring in the western Upper Peninsula of Michigan and upper Wisconsin. Mean annual 7-day low-flow runoff also increased during this period by an average of 0.048 cubic feet per second per square mile. They also determined that precipitation in the basin was 10% lower for the period 1915-1935 than for the most recent 20 years of record analyzed. The long-term amount of precipitation is the most important factor controlling groundwater discharge to streams and needs to be better understood in order to evaluate the impact of development. Recommended Future Research Neff et al. (2005) recommended that long-term trend analysis of baseflow be done for the basin. This will help determine whether changes are happening in groundwater inflow to streams and provide monitoring strategies to track these changes. Some aspects of this work are being done by Hodgkins and others as part of a basinwide study of water availability and use (Grannemann and Reeves, 2005). The Role of Groundwater in Supporting Ecological Systems Recent Research Groundwater is essential to maintain stream flow during periods of low or no precipitation as well as to maintain wetlands in many hydrologic settings. This relatively constant source of water is recognized as the most important factor to maintain ecosystem function in many streams and wetlands (Masterson and Portnoy, 2005). The availability of suitable thermal habitat for fish in streams is strongly related to the amount of groundwater discharged to a given stream segment. An assessment tool for estimating the impact of groundwater withdrawal on fish in Michigan streams is currently under development. Recommended Future Research The effects of groundwater withdrawal on the ecosystem function of streams are probably the most limiting factor associated with the use of groundwater in most of the Great Lakes Basin. Techniques to evaluate the effects of water withdrawal on fish should be further developed and expanded to incorporate more species. Water managers should coordinate these techniques among states and provinces so that common or complementary methods are used in all jurisdictions (Marbury and Kelly, 2009). 18
Page 1 and 2: AReportoftheGreatLakesScienceAdviso
Page 3 and 4: Citation: Great Lakes Science Advis
Page 6: Commissioners’ Preface The Great
Page 9 and 10: 2 required to monitor basin groundw
Page 11 and 12: 4 Systems have a 30-year lifespan d
Page 13 and 14: 6 Groundwater quality is routinely
Page 15 and 16: 8 Transmittal Letter Groundwater/An
Page 17 and 18: 10 Acknowledgements, Activities and
Page 19 and 20: APPENDICES Appendices A through L p
Page 21 and 22: INTRODUCTION Groundwater, a major n
Page 23: 16 DESCRIPTION OF NATURAL SYSTEMS M
Page 27 and 28: Estimates of the Level and Extent o
Page 29 and 30: APPENDIX B Threats to Groundwater Q
Page 31 and 32: 24 PATHOGENS Bacteria, viruses and
Page 33 and 34: Viruses Viral pathogens continue to
Page 35 and 36: SPECIFIC EPISODES Walkerton In 2000
Page 37 and 38: 30 season. The sampling sites inclu
Page 39 and 40: 32 Curriero, F.C., Patz, J.A., Rose
Page 41 and 42: Infection of a suitable host specie
Page 44 and 45: APPENDIX C Threats to Groundwater Q
Page 46 and 47: Road salt has significant toxic eff
Page 48 and 49: converted to nitrite in the human s
Page 50 and 51: Atrazine Atrazine is an extensively
Page 52 and 53: Wisconsin DNR keeps track of about
Page 54 and 55: Table 1. Chemical Contaminants in G
Page 56 and 57: isks for 23 diseases in six contigu
Page 58 and 59: Figure 1. Number* of waterborne-dis
Page 60 and 61: Guidelines for Canadian Drinking Wa
Page 62 and 63: APPENDIX D Threats to Groundwater Q
Page 64 and 65: Figure 1. Source: General Descripti
Page 66 and 67: (Gorman and Halvorsen, 2006). Any s
Page 68 and 69: Table 3. Washtenaw County, Michigan
Page 70 and 71: that the OWTS would last until it w
Page 72 and 73: REFERENCES AND BIBLIOGRAPHY Aglie,
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Septic Tanks - Septic Tank Articles
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INTRODUCTION Leaking underground st
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sites that were previously closed,
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Table 1. USTs in Great Lakes States
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Estimation of Costs for Remediation
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Table 6. Operational Compliance of
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80 Indiana Government. (2007, Febru
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82 GLOSSARY AST - above ground stor
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INTRODUCTION 84 Hazardous wastes ar
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The town of Kincardine, Ontario, ha
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88 • The monitoring and surveilla
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However, the U.S. EPA has been relu
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92 Johnson, B.L. & DeRosa, C.T. (19
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PAHs - Polycyclic aromatic hydrocar
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INTRODUCTION An abandoned well is d
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Figure 6: Leaking oil well Source:
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CONTAMINANT SOURCES 100 During any
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Nearly 16 million operational water
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• Development of a targeted progr
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106 Michigan Department of Environm
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APPENDIX H Threats to Groundwater Q
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far reaching. Road salt can inhibit
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112 Desalinization Potential water
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Gray, J. (2004, January). Brine Spr
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INTRODUCTION 116 In 2003 there were
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118 feed has increased to upwards o
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References and Bibliography 120 Arn
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APPENDIX J Threats to Groundwater Q
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for recreational purposes and destr
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126 errors (human or mechanical), p
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Apparent Losses Old meters are like
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Figure 6. Examples of Windsor, Onta
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REFERENCES AND BIBLIOGRAPHY 132 Ada
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134 Levy, S. (2004, November 16). T
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APPENDIX K The Châteauguay Transbo
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138 the clay sediments of the St. L
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REFERENCES AND BIBLIOGRAPHY Bureau
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INTRODUCTION 142 Groundwater law ac
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144 • Water withdrawn be returned
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146 found to be failing. Now, with
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Part 373: Third Stage Treatment Lag
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150 Chapter 1501:15 Soil and Water
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152 Title 29 - Water Resources Mana
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APPENDIX M List of Acronyms ADHD -
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Groundwater in the Great Lakes Basin

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