Wildfire Impacts on Water Quality

This project seeks to understand the generation, mobilization, persistence, and transport of polycyclic aromatic hydrocarbons (PAHs), aliphatic compounds, metals, nutrients, and suspended material associated with wildfires. The primary focus over the past three years has been on the long-term effects of the 2018 Woolsey Fire on the Malibu Creek watershed. We have collected water,soil, and sediment samples throughout the Malibu Creek Watershed monthly and during/after significant precipitation events since November 2018 (a total of 23 sampling events have been conducted).

Total PAH concentrations in water samples collected from the Malibu Creek watershed following the Woolsey Fire.

Molecular ratio approaches were used to identify predominant sources of PAHs in samples. Some sites (e. g., Site 3 shown here) continued to show a pyrogenic (i. e. fire-derived) source, while other sites in the watershed (e.g., Site 5) showed a shift from pyrogenic to petrogenic after the first wet season following the fire.

Wildfire Soil Chemistry

The project to date has involved collection of nearly 100 soil samples from eight different Southern California wildfires and background locations. The soil samples support multiple project goals, including identifying chemical differences among fires and how organic compound concentrations change over time.