Stakeholder participation is a requirement for environmental decision-making in the European Union. Despite this, numerous instances can be seen in water governance in which stakeholders feel undervalued and unheard, thereby creating unfavourable procedural outcomes, resistance and conflict. In this article, we propose that a process of early-stage deliberation constructed around the values of the stakeholders involved can reduce, and even prevent such conflicts. We suggest that if values that stakeholders perceive as relevant can be identified and discussed as part of the deliberation process then (1) stakeholder preferences can change, and (2) participants can develop a mutual understanding of each other’s values and perspectives. To explore these propositions, facilitated workshops were conducted at two Dutch water institutes, based around the topics of land subsidence and the pharmaceutical contamination of water systems. Participants deliberated on values that they considered relevant. The results suggest that mutual understanding of stakeholders’ perspectives increases as a result of value-based deliberation.

To better understand the impact of deliberations during participatory policymaking events, we introduce and explore the concept of group proximity. An example of such events is citizens' summits, during which many parallel groups deliberate on solutions for a policy issue. At the summit that was studied, each group followed a value deliberation process with the aim to increase mutual understanding among participants. They were asked to rank the solutions in their order of preference before and after the deliberation. From these rankings, group proximity can be calculated with a rank correlation, enabling a precise comparison of participants' preferences in each deliberative group. High group proximity indicates very similar rankings in a deliberative group, while low group proximity demonstrates the opposite. Comparing group proximity of the before and after rankings shows if a group ranked convergent, unchanged or divergent. This measure allows for a quantitative analysis of early-stage public policymaking processes.