Liesl Tiefenthaler is a marine biologist working for the watersheds department. She received her Bachelor of Science degree in 1991 from California State University, Long Beach. She joined SCCWRP in July, 1994. Currently she is working on characterizing contaminant concentrations from specific mass emission (ME) in-river and different land use locations indicative of source categories in urban southern California watersheds in order to assess factors that influence variability in stormwater runoff concentrations.