Preface. Contents. Tables. Illustrations. 1. Introduction. Overview of this Report. Acknowledgements. Scope of Data Presented. Reporting of Isotopic Data. Regional Geology and Stratigraphy. Hydrogeology and Hydrochemistry. 2. Limitations of Sampling and Analytical Procedures. Contamination of Samples. Comparison of Carbon Isotope Results From Conventional and AMS Measurements. Evaluation of Replicate Analytical Data. 3. Infiltration Conditions. Isotopic Composition of Modern Recharge. Isotopic Composition of Groundwater. Noble Gases in Groundwater. 4. Dating by Radionuclides. Introduction. Overview of the Sources of the Individual Isotopes. Detection of Young Water Components With 3H and 85Kr. 39AR Results for Waters from Sedimentary Formations. 5. Carbonate Isotopes. Overview of Groundwater Carbonate Evolution. Age Interpretations of Dissolved Carbonate Isotopes. Isotopic Composition of Carbonate Minerals and Water. 6. Isotopes Formed by Underground Production. Introduction. Chlorine-36. Argon-39 and Argon-37. 3HE and 4HE. 40Ar/36Ar Ratios. 7. Formation-Specific Characteristics of Groundwaters. Sulphur and Oxygen Isotopes in Sulphate and Sulphide. Strontium Isotopes in Groundwaters and Minerals. Uranium and Thorium-Series Nuclides. 8. Synthesis of Isotope Results. Tertiary and Malm. Dogger, Lias, and Keuper. Muschelkalk. Buntsandstein, Permian and Crystalline. Inter-Aquafer and Regional Flow. Recommended Further Studies. 9. Summary Analytical Results and Interpretative Methods. Hydrogeological and Hydrochemical Conclusions. 10. Literature Cited. Appendix. Maps.