Run-of-River Hydroelectric Projects and Cumulative Impacts in British Columbia

The expansion of run-of-river (ROR) hydroelectric operations in British Columbia since the early 1990s has raised concerns over the potential cumulative effects arising from multiple ROR sites and additional land-uses within a watershed. While this concern has been expressed by a multitude of interest groups, cumulative effects assessments (CEAs) are still a developing concept, and ROR-centric CEAs are often hard to find or lacking in detail. A central issue is the lack of research regarding the environmental impacts of ROR operations and their associated infrastructure. To address these challenges, this study focuses on identifying the key land-use and aquatic changes that have occurred in the Clowhom River watershed in southwestern BC, an area that has recently undergone ROR development. The potential impacts of each ROR project component were identified through a literature review; these impacts were then examined in a cumulative manner along with the potential impacts from additional watershed activities and climate change. Results suggest that the cumulative effects of ROR developments will be largely determined by the pre-ROR state of watershed development and infrastructure.