The Upper Penticton Creek Watershed Experiment, BC, Canada

The Upper Penticton Creek (UPC) watershed experiment was initiated in 1982 in response to concern over the effects of logging on water supplies in the Okanagan Valley. The project was planned and sites selected cooperatively by the BC and Canadian governments and Weyerhaeuser Co. Ltd. Three small watersheds located 20 km northeast of Penticton, BC, were chosen for study and by 1985, logging road access and construction of streamflow gauging stations was complete. The experiment follows a paired watershed design with a 10-year pre-treatment period followed by logging and monitoring to assess the influence of increasing clearcut area on watershed hydrology.

The project initially focused on streamflow quantity with a lead scientist, a graduate student, and a contractor. Gradually the team expanded, as did the environmental monitoring network, providing greater opportunities for graduate students and new research. A network of climate stations, snow survey grids, a groundwater well, water sampling sites and channel reach cross-sections support research on forests and snow, water balance, surface-groundwater interactions, channel morphology, water quality, aquatic habitat, modelling and climate change response. A clear shift in the hydrologic regime occurred following clearcutting 50% of the treatment area, with advanced snowmelt-dominated high flows and decreasing late-summer flows. Changes in high flows did not have a significant effect on stream channels due to low stream power, coarse substrate and limited riparian disturbance. Following harvest, suspended sediment and turbidity increased but chemical water quality did not. Increased water temperatures in these cold headwater streams increased the number of aquatic invertebrates and altered the community structure, suggesting some reduction in aquatic community health. Recovery of snow processes is beginning where young trees are ≥5 m tall. These results are being used to inform watershed risk and cumulative effects assessments and forest development planning.

As one of the BC's longest running field experiments, UPC provides a legacy of data and established infrastructure on which to build future research and test new technologies, and a permanent site where ideas can be shared among researchers, practitioners, students, and the public.