SUBJECT: PRELIMINARY RESULTS OF STUDY #214: MONITORING THE OCCURRENCE AND CONCENTRATION OF ESFENVALERATE AND

This memorandum provides results of water sampling conducted in tributaries to the Sacramento and San Joaquin Rivers by the Department of Pesticide Regulation (DPR) for the Surface Water Protection Program. Information presented is from November 2002 through March 2003. Results from chemical analysis conducted by the California Department of Food and Agriculture (CDFA) and bioassays conducted by the California Department of Fish and Game (DFG) are also presented here. The primary objectives of this monitoring project were to determine (a) if the insecticides esfenvalerate and permethrin are moving offsite into surface waters, during winter storm events, and if so, (b) the typical range of concentrations that may be observed. A secondary objective was to obtain more data on organophosphate (OP) insecticides and selected herbicide residues in surface water. This memorandum does not include an in-depth interpretation of the data, which will be provided in the final report