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Circular 1224--Assessing Ground-Water Vulnerability to Contamination: Providing Scientifically Defensible Information for Decision Makers

CONCLUSIONS

Scientists can provide water-resource decision makers scientifically defensible information for the assessment of ground-water vulnerability and(or) intrinsic susceptibility. To the extent that uncertainties in the assessment can be elucidated either quantitatively or qualitatively, the scientific defensibility and ultimate usefulness of the product will increase. Science objectives should be clearly distinguished from water-resource management objectives. Ultimately, successful ground-water-vulnerability assessments blend scientifically defensible analyses used to meet science objectives with additional interpretations by water-resource decision makers to meet management or policy objectives (fig. 14). Therefore, careful communication and feedback between the water-resource decision makers and scientists are required during all phases of a ground-water-vulnerability assessment from planning to interpretation of results. The information, citations, and hypothetical examples provided in this report highlight how basic underlying hydrologic and chemical principles and various assessments of the important factors that control ground-water vulnerability are essential components of a scientifically defensible regulatory and policy decision-making process.

fig14
Figure 14. The interpretation and practical use of an assessment is best served by interactions and feedback between the scientists and the decision makers. This is particularly true as the complexity of an assessment increases. These interactions and feedback can remove some of the need for overly simplistic assessments that produce subjective categorizations. Successful ground-water-vulnerability assessments blend scientifically defensible analyses based on clear science objectives with additional interpretations by water-resource decision makers to meet management or policy objectives.

ACKNOWLEDGMENTS

We are grateful for the thoughtful technical reviews of this Circular provided by Wayne W. Lapham, Gregory E. Granato, Janice R. Ward, William M. Alley, and William L. Cunningham. Many other U.S. Geological Survey colleagues including Jack E. Barbash and Bernard T. Nolan provided important insights and comments. We are also grateful to Sandra C. Cooper for her thorough editorial review and Patricia S. Greene for preparing the final manuscript and illustrations.


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