The cumulative effects of watershed development and large water withdrawals are placing the sustainability of freshwater resources at risk due to alteration of watershed hydrology, stream geomorphology, groundwater recharge, and adverse effects to the aquatic ecology of water resources. The consideration of cumulative environmental effects in development decisions under current project-specific assessment does not fully encompass the interacting effects of multiple stressors over space and time. As a result, the cumulative effects of land uses and development on watershed processes are not properly assessed and managed. There is a recognized need to shift from local, project-scale cumulative effects assessments to broader, landscape, or regional scale assessments to accurately assess cumulative effects to watershed processes and river system condition. The problem is that there is little understanding of the current capacity to do so. This research: i) developed a set of indicators for evaluation of regional capacity to support watershed cumulative effects assessment and management (CEAM) requisites, ii) applied those indicators to the South Saskatchewan Watershed (SSW), iii) identified capacity needs and constraints to watershed CEAM in SSW, and iv) identified lessons learned and opportunities for capacity building to support watershed CEAM principles and practice. Capacity indicator questions were developed for a set of eight institutional requirements for watershed CEAM, identified from a previous study of watershed CEAM in the SSW. Research methods included a web-based survey of academics, regulators, industry and environmental organizations, which consisted of both closed ended and open-ended questions based on the capacity indicators. Survey results were analyzed using the Statistical Package for the Social Sciences and qualitative methods. Results indicate that the primary threats to water quality and quantity in the SSW, as identified by study participants, are broad-scale stressors that are not subject to project-specific environmental assessment regulations. To address these broad-scale stresses, cumulative effects assessment at the regional level needs to be done; however, it was identified that there is currently a lack of mechanisms to support watershed CEAM. The need for a lead agency, multi-stakeholder collaboration, and financial and human resources were identified as the most important requisites from the research results for implementing and sustaining watershed CEAM programs. Research results revealed that watershed CEAM cannot be driven solely ‘bottom-up’ and government must lead watershed CEAM activities. Participants noted that there is collaboration ongoing in the SSW to meet CEAM objectives, but it is limited. There is a lack of clarity around common goals for watershed and sub-watershed management, and a lack of transparency in sharing data. Many participants commented that expertise is available for watershed CEAM, but there is a lack of organizational and financial resources to develop successful plans and actions.