Our main goal is to investigate the extent to which the interaction of wildfire ash with precipitation and surface runoff or its incorporation into the soil can lead to the post-fire mobilization of metals/metalloids (e.g., copper, zinc, cadmium, lead, arsenic, chromium, antimony), nutrients (nitrogen, phosphorus) and a variety of organic chemicals (e.g., polycyclic aromatics). The mobilization of contaminants and nutrients in watersheds that sustain adjacent and downstream human populations could contaminate the clean water and the recharge of groundwater aquifers that serve as sources of potable water.