SUBJECT: PRELIMINARY RESULTS OF PESTICIDE ANALYSIS AND ACUTE TOXICITY TESTING OF MONTHLY SURFACE WATER MONITORING FOR THE RED IMPORTED FIRE ANT PROJECT IN ORANGE COUNTY,

During July 2001, surface water samples were collected from five sites in Orange County, California. Water samples showed no detects of fenoxycarb, hydramethylnon, pyriproxyfen, dimethoate, malathion, and methidathion. Bifenthrin was detected in two samples at 0.402 and 0.492 parts per billion (ppb) at the two nursery sites. Chlorpyrifos was detected at one nursery site at 0.043 ppb. Diazinon was detected in three samples ranging from 0.107 to 0.944 ppb at two urban and an integrated site. Toxicity was tested at San Diego Creek at Campus Drive, an integrated site. This site was not toxic (10 % mortality) to Ceriodaphnia dubia in the water collected. Water samples collected from a mitigation filter strip planted with Canna showed a 51 % reduction of bifenthrin concentrations