Water temperature plays a fundamental role in structuring freshwater ecosystems. It influences the physiology and behaviour of fish through all life history stages, affecting growth, survival and distribution of individuals and populations, as well as species interactions within fish communities. Moreover, evidence suggests that changing climate conditions have led to warming of streams across western North America and future projections suggest that warming will continue for the foreseeable future. Such thermal changes can lead to fragmentation of freshwater habitats across the landscape, especially for vulnerable species such as bull trout and Pacific salmon. Managers of aquatic ecosystems across the Great Northern and North Pacific Landscape Conservation Cooperatives need to consider the implications of climate change and other stressors on their management actions. Yet in British Columbia broad-scale planning efforts are, at present, only possible by using crude climate surrogates like air temperature or elevation, which can be weakly correlated with stream temperatures. In British Columbia a regulatory tool is available that allows managers to designate “Temperature Sensitive Streams” (TSS) to protect critical fish-bearing streams that could be altered by stream heating due to forest harvesting in riparian and upslope areas as well as climate change.

The stream temperature modeling infrastructure described within this report is intended to provide the starting basis for a science-based tool that can be used to enhance management, monitoring, and coordination of stakeholder engagement around aquatic resources in British Columbia and internationally with the US This work leveraged the technologies, protocols, and advancements made through the NorWeST project funded for the US portion of the Great Northern and North Pacific Landscape Conservation Cooperatives, while also integrating the related experience and data that has been developed in British Columbia. The work builds on existing spatial layers and compilations of data from existing agency temperature monitoring efforts in British Columbia, with the purpose of providing consistent modeling frameworks and sets of reference conditions.