I have now read the reviewer comments and author responses for this manuscript. Both reviewers agree that this manuscript is a worthwhile contribution to the literature. At this point, I now direct the author's to revise the manuscript according to their proposed changes while asking that the authors pay close attention these additional points as they revise the manuscript:

1 - I would remind the authors of the HESS data policy (http://www.hydrology-and-earth-system-sciences.net/about/data_policy.html). Both reviewers note that the underlying data used to derive the causal probability thresholds is not presented in the manuscript. This is a key piece of missing information and as Reviewer 2 points out, is a necessary component to verifying the approaches used in the manuscript. I understand that the authors reason that they wish to publish this as part of a separate manuscript but, according to the HESS data policy, this information should be made available with this manuscript. Otherwise, any analyses dependent upon this data needs to be removed from the manuscript.

2 - In some cases, the authors have responded with statements such as "this can be expanded on if required in the MS." (page C4 of author comments). Both reviewers have clearly spent a great deal of time reviewing the manuscript and offering what I feel are highly constructive comments that seek to improve a manuscript they believe makes a useful contribution to the literature. I ask that the authors carefully consider their responses and incorporate them to as much extent as possible. It is not typically the job of the editor to determine which reviewer comments can be ignored or which must be followed.

3 - Both reviewers note the density of the material and the need for clarity and improved readability. Both reviewers use the phrase "tough read" to describe this manuscript. I agree that the manuscript needs careful revision to improve clarity and readability. Further, the reviewers make constructive comments as to areas of the manuscript where the text is difficult to understand; however, the author responses more often than not state that the material was in the manuscript but perhaps missed by the reviewer. These responses miss the point of the review comments. In these sections, the the text in the manuscript was not clear enough to convey the information the reviewer was seeking. The manuscript, therefore, needs to be revised in these sections to be more understandable to a reader.

4. In the next revision phase, where the authors will respond to the review comments with how they actually incorporated the comments, I ask that the authors start a new paragraph for each comment and response pair, as was done in their supplemental response. I do thank the authors for pulling out the comments submitted from the marked-up manuscript and placing them in their review responses. I know this was a time-consuming task and it was very much appreciated.

Given these substantial revisions, I will send the manuscript out for an additional set of reviews before making a final decision.

I wish the authors my best in the revision process.

Kindly,
Stacey

The revised manuscript has received two reviews and both reviewers agree this paper will provide a useful contribution to the literature on ecological flow evaluations and request minor revisions for the manuscript to be published.

I now ask the authors to revise the manuscript accordingly and provide detailed responses to the comments of the reviewers. After this is complete, I will review the author responses and revised manuscript to ensure all comments have been addressed before final acceptance of the publication in HESS.

I thank the authors for their revisions to the manuscript. In my final reading of the manuscript, I noticed that the figures and their descriptions are no stand-alone.

For example, in Figure 1, the RR abbreviation is not explained. This could be corrected easily by changing the caption to read, "The upper Senqu River study area with Risk Regions (RR) established for the study including dams associated..." Before final acceptance, I ask the authors to carefully review the HESS manuscript guidelines to ensure compliance:
https://www.hydrology-and-earth-system-sciences.net/for_authors/manuscript_preparation.html

After these minor technical corrections have been made, I look forward to final acceptance of this manuscript.