This study investigates the different stakeholder based discourses and challenges around the Franconian Lake District (FLD), a recently constructed large reservoir system in Germany. The construction and operation of reservoirs represent a massive alteration of their natural and social environments leading to discourses and potential conflicts between a wide scope of heterogeneous interest patterns. Studies have shown that large reservoirs can be an important contributor to water supply, irrigation, energy storage and therefore climate change mitigation on a global scale, which brings these conflicting interests to a broader societal concern. Yet, information about conflicts around existing (German) reservoirs is limited. To assess which issues and conflicts appear on the daily agenda and how they are perceived, communicated and addressed by the stakeholders, a total of 609 articles in the Nürnberger Nachrichten and 22 semi-structured expert interviews were analysed, using qualitative content analysis. The results show that discourses at FLD are predominantly determined by economic factors. Management issues are dominated by discussions about cyanobacteria, which can pose a health risk, thereby impeding recreational use of the lakes and consequently causing economic losses and an image problem for the region. The issue is also strongly interlinked with other aspects of concern and therefore one of the main challenges at the FLD. Due to the construction of the lakes and the evolving strong tourism sector, the formerly agricultural region was subject to a major structural change linking together a very heterogeneous set of interests. The results of this study can help in establishing a management framework to suit all stakeholders and possibly be transferrable to similar projects.

Reservoirs are a common way to store and retain water serving for a multitude of purposes like storage of drinking and irrigation water, recreation, flood protection, navigation, and hydropower production, and have been built since centuries. Today, few reservoirs serve only one purpose, which requires management of present demands and interests. Since each reservoir project will cause negative impacts alongside desired advantages both on a local, regional and global scale, it is even more urgent to develop a common management framework in an attempt to mitigate negative impacts, incorporate different demands and make them visible within the discourse in order to avoid conflicts from early on. The scientific publications on reservoirs are manifold, yet a comprehensive and integrative holistic tool about management of this infrastructure is not available. Therefore, a comprehensive and integrated conceptual tool was developed and proposed by the authors of this paper that can contribute to the sustainable management of existing reservoirs. The tool presented herein is based on the results from the interdisciplinary CHARM (CHAllenges of Reservoir Management) project as well as the condensed outcome of relevant literature to aid and enhance knowledge of reservoir management. The incorporated results are based on field, laboratory and empirical social research. The project CHARM focused on five different aspects related to existing reservoirs in southern Germany (Schwarzenbachtalsperre, Franconian Lake District), namely: sedimentation of reservoirs, biostabilisation of fine sediments, toxic cyanobacteria(l) (blooms), greenhouse gas emissions from reservoirs and social contestation, respectively consent. These five research foci contributed to the topics and setup of a conceptual tool, put together by the research consortium via delphi questioning, which can be found alongside this publication to provide insights for experts and laymen. Conceptualising and analysing the management in combination with quantitative and qualitative data in one descriptive tool presents a novelty for the case studies and area of research. The distribution within the scientific community and interested public will possibly make a positive contribution to the goal of sustainable water resources management in the future.