To understand the concerns, approvals and disapprovals of expert opinions about managerial issues from around reservoirs this study uses the approach of Fuzzy Composite Programming (FCP) in direct questionnaires to parameterize and rate a set of indicators with statements about managerial issues concerning societal implications by the responding experts. The personal ratings get summarized in four different layers and converted into one final numerical value which will be in the range of 0 as the absolute disapproval of the indicators and 1 as the absolute approval of the indicators. The FCP approach thereby rates the individual indicator, secondly the indicator category, thirdly the compensational factor and fourthly the dimensions of sustainability. This facilitates a rapid comparison of results of rather complicated sets of pre-set indicators in topics reaching from legal issues to societal concerns in one final numerical value to identify crucial topics and start open debates. This study was carried out as a methodological test at two water reservoirs in southern Germany. The results show a general possibility of using a rather retrospect methodology towards current ratings of experts in the field of reservoir management. 10 respondents answered the FCP questionnaires, 5 at each study site. The scores of the calculation showed a higher level of positive connection in the case of the Schwarzenbachtalsperre (SBT) with a score of 0.77, compared to a score of 0.54 in the case of the Franconian Lake District (FLD). Apart from the pure numerical scores, FCP can show conflicting issues and possible compromise solutions between the different stakeholders, in/based on the individual ratings. The findings could help reach a more sustainable management of water resources that includes all stakeholders, by pointing out debatable implications.