The cumulative effects of natural and human-induced disturbances to terrestrial and aquatic ecosystems are among the most pervasive issues facing environmental management. Many of the policies and instruments in place to deal with cumulative effects function at local scales and often in response to specific resource development proposals, such as regulatory environmental and socioeconomic impact assessments. There has emerged in recent years a recognized need amongst the practitioner, scholarly, and decision maker communities to advance cumulative effects assessment, monitoring, and management efforts to more regional (e.g. ecosystem, watershed) scales. Doing so requires new tools and technologies, big data, regulatory and policy innovation, collaboration and partnerships, and a greater role for social considerations and Indigenous knowledge systems.

This Special Issue of Environmental Management is focused on innovations in cumulative effects assessment, monitoring, and management. We are interested in papers from all sectors and disciplines, with special attention to the following topics:

•Theoretical or conceptual advances in cumulative effects principles and frameworks

•Innovations in cumulative effects assessment methods or monitoring

•Regional frameworks for cumulative effects assessment, monitoring, or management

•Governance and institutional arrangements for improved cumulative effects analysis or management

•Determining thresholds or limits to support cumulative effects decisions

•Spatial tools and information management for assessing and characterizing cumulative effects

•Regulatory challenges and opportunities for improving cumulative effects management

•Social and cultural dimensions of cumulative effects, including legacy effects and Indigenous knowledge systems

•Lessons from innovative case studies and applications in cumulative effects assessment, monitoring or management, including Indigenous-led initiatives

Hydropower remains a vital part of the global energy transition, offering renewable and flexible electricity generation. However, its sustainable development requires innovative approaches not only in technology and policy, but also in planning and management—to effectively balance economic viability, ecological integrity, and social responsibility. This collection will bring together a diverse community of researchers, practitioners, and policymakers committed to advancing sustainable hydropower development and integrated water and energy management—particularly in light of accelerating climate challenges and the growing demand for resilient, cross-sectoral solutions. The collection presents actionable, peer-reviewed contributions drawn from the 3rd International Conference on Sustainability in Hydropower (SUSHP2025; https://sushp2025.boku.ac.at/), held in Vienna, Austria, and online from 2–5 September 2025.