The helium measurements have been added as supplementary data and the author made a clear difference between this study Helium measurements and other tracer studies we are citing.
With respect to the helium measurements, the references to the primary documentation requested by the reviewer in comments to v.1 of the manuscript are not provided, nor do the authors provide any comment as to why they deem this unnecessary. Section 4.3 Helium concentrations and isotopic composition measured in groundwater, is framed around results from previous studies. Providing references to these original studies (including access to the actual data that allow objective verification) rather than referencing to summary papers would be more in line with scientific publishing practice. If the primary documentation is not accessible, the authors should state this clearly.