Hydropower generates renewable energy, but also local environmental damage. In Sweden, hydropower facilities are undergoing a process of environmental adaptation which aims at protecting water environments while also ensuring electricity production. Regional stakeholder collaboration has been introduced as part of the decision-making process. To explore opportunities and challenges with this governance strategy, this study analyses hydropower collaborations using the Integrative Framework for Collaborative Governance (Emerson & Nabatchi, 2015). Several types of documentation from all 27 finished collaborations have been collected and subjected to a qualitative thematic analysis. The results show that the main challenges are related to organising collaboration, balancing interests and managing needs for knowledge. While these appear closely interrelated, knowledge emerged as especially important. Knowledge contestation was a major driver for disagreements over interest balance, and accepted knowledge can overall be seen as a crucial capacity for joint action. The analysis also identified a discrepancy between stakeholders’ expectations for interest negotiation and reality. More research is however required to establish the connection between collaborative procedural arrangements and agreement among stakeholders.