In the lab, USGS scientists analyze sediment samples collected from stream banks to test for contaminants produced by wildfires. The toxic chemicals can be transported downstream by runoff following rainstorms in the burned regions.
In August of 2020, the enormous CZU wildfire complex consumed over 85,000 acres in San Mateo and Santa Cruz Counties, leaving scarred landscapes in the hilly region. Runoff from large rainstorms in the winter months can carry contaminants from the soils within these burned-out forests. Forest fires and the fmaterials they burn introduce chemicals into watersheds that can harm wildlife and contaminate drinking water. Here, research geologist Renee Takesue, of the USGS Pacific Coastal and Marine Science Center, samples stream sediment in the lower parts of burned watersheds to measure concentrations of several kinds of contaminants following major storm runoff in late January 2021. Our team hopes to compare these with samples taken from the same watersheds after the fire. Samples must be collected before too much time has elapsed since the wildfires, before post-fire storms wash the burned material downstream.