Hydrophobic (sediment-associated) pesticides were measured in sediment samples collected from 82 wadeable streams and in biofilm in 54 of those streams in the Central California Foothills and Coastal Mountains ecoregion.115 current-use and 3 legacy pesticides were measured in stream sediment; 93 of the current-use pesticides and the same 3 legacy pesticides were measured in biofilm. On average 4 times as many current-use pesticides were detected in biofilm at a site (median of 2) as in sediment (median of 0.5). This data release provides data for the pesticide concentrations, information on the pesticide compounds, and input data and R scripts for statistical models used in the analysis presented in the journal article "Biofilms provide new insight into pesticide occurrence in streams and links to aquatic ecological communities," by BJ Mahler, TS Schmidt, LH Nowell, SL Qi, PC Van Metre, ML Hladik, DM Carlisle, MD Munn, and J May, http://dx.doi.org/xxxxxxxx.