For many utilities, an essential component of assessing source water vulnerability includes anevaluation of the impacts of changes in vegetative cover within source watersheds. In many parts ofNorth America, forested environments are critical source water regions; in those environments,wildfires comprise significant land disturbances that greatly impact both water quality andquantity in headwaters. In 2003, the Lost Creek wildfire impacted the upper Oldman River Watershedin Alberta, Canada. It was one of the more severe recorded fires in the eastern slopes of the RockyMountains. Many aspects of streamflow and water quality were impacted and have been studied duringfive subsequent years of watershed recovery. The potential impacts of wildfire on drinking watertreatment were assessed by collecting and evaluating a comprehensive data set describing the basichydrology and water quality (turbidity, total phosphorous, total kjeldahl nitrogen, and dissolved organiccarbon) from source watersheds with varying degrees of land disturbance associated with wildfire(unburned, burned, and post-fire salvage logged) over four years after the wildfire. Jar tests wereconducted to investigate the wildfire and salvage-logging associated changes in water quality andquantity relative to unburned environments and their implications to drinking water treatment. Theobserved vegetation and land use impacts on water quality of the Oldman watershed in Alberta, Canadaare representative of increasing pressures related to land use change in many regions of North America.Compared to unburned watersheds, the observed increased turbidity, TP, TKN and DOC levelsobserved in streams draining burned and salvage-logged watersheds present important economic,logistical and operational challenges for water suppliers, managers and regulators. The data show thatsuch wildfire related changes in surface water quality can increase coagulant demand, sludge productionand oxidant demand/fluence requirements; they also can increase public health protection challenges(potential increases in microcystins and DBPs). Accordingly, failure to manage and protect criticalsource water regions will have significant cost and compliance implications that will influence the longterm sustainability of water management. Includes 21 references, tables, figures.
