Wildfire Impact Assessment in Watersheds of Alberta’s Regional Aquatic Monitoring Program

Wildfire impact on boreal watersheds was assessed across Alberta’s Regional Aquatics Monitoring Program (RAMP) domain by integrating multidecadal river, lake, and sediment physical–chemical data with historical wildfire perimeters, polycyclic aromatic hydrocarbon (PAH) indicators, continuous multiparameter sonde records, and pre-/post-fire hydrologic simulations. Site classification, distinguishing reference, industrial, wildfire, and combined influences, was used to enable spatial and temporal comparisons before, during, and after fires. Our synthesis indicated that wildfire acts as an important disturbance that alters watershed connectivity and transport pathways, resulting in shifts in water quality and quantity in surface waters and longer-term adjustments retained in sediments. The interpretation of chemical signatures, including PAHs, was complicated by overlap between areas with wildfire and industrial activities, highlighting cumulative effects and the importance of spatio–temporal context when assessing and quantifying source contributions for long-term resource sustainability. Hydrologic alteration emerged as the dominant downstream wildfire effect, emphasizing the need for long-term continuous monitoring of fire-responsive indicators, in addition to improved assessment of subsurface pathways in wildfire-prone boreal systems.