Dear authors

you work has received three in depth review. Main point for me was the discussion concerning the applicability of the method when having a smaller amount of groundwater observations. I agree with you that a full mC analysis is a bit outscope of this article. I agree with the analysis using a smaller subset of borehole observations. Also the second main point, the uncertainty of the end-member analysis is adressed adequately.
Of course such a data set as you use is somewhat extraordinary and will not be found often to say the least. However, you are right that this should not restrict using this data for in-depth analysis and method development: as you did.
In all I think this is a very interesting well written and structured paper, and I therefore accept the paper with minor changes addressing all the issues the reviewers raised.

Best regards,
Thom Bogaard
I look forward receiving the revised manuscript which I will

Dear authors

thanks for the resubmission and the active discussion in HESSD. The paper is now accepted for publication.
Kind regards, Thom Bogaard