SUBJECT: PRELIMINARY RESULTS OF PESTICIDE ANALYSIS OF MONTHLY SURFACE WATER MONITORING FOR THE RED IMPORTED FIRE ANT

During March 2002, monthly surface water samples were collected from four sites in Orange County, California. Water samples showed no detects of fenoxycarb, hydramethylnon, pyriproxyfen, chlorpyrifos, dimethoate, malathion, and methidathion. Bifenthrin was detected in one sample at 0.357 parts per billion (ppb) at one nursery site. Diazinon was detected in two samples at 0.075 and 0.084 ppb at two urban sites. SCOPE OF THIS MEMORANDUM This memorandum reports results of water sampling conducted by the Department of Pesticide Regulation (DPR), under interagency agreement with the California Department of Food and Agriculture (CDFA), for the Red Imported Fire Ant (RIFA) control project. Data included here are from the March 12, 2002 monthly monitoring, and encompass results from chemical analyses. This memorandum summarizes results for bifenthrin, fenoxycarb, hydramethylnon, pyriproxyfen, and five organophosphorus insecticides: chlorpyrifos, diazinon, dimethoate, malathion, and methidathion. Only bifenthrin, fenoxycarb, hydramethylnon, pyriproxyfen, and chlorpyrifos are used in the RIFA control program. The other four organophosphates are in our multiresidue analytical method and are included in this report to assist in the interpretation of th