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detected in Crabtree Creek, which drains an urban basin, and the Neuse River near Clayton, located immediately downstream from Raleigh. Concentrations of the insecticide carbaryl also were high- est at these two sites, as well as the Neuse River at Smithfield. These results are consistent with national findings, which indicate that insec- ticide concentrations generally are higher in urban streams than in other settings (U.S. Geological Survey, 1999). Previously collected pesticide data from the Tar River at Tarboro (site 14) and the Neuse River at Kinston (site 28) indicate that detections of metolachlor and atrazine are not uncommon, and that concentrations in floodwaters were somewhat lower than concen- trations previously measured under normal flow conditions. For exam- ple, in 20 samples collected from the Tar River at Tarboro (site 14) between 1993 and 1994, the median concentration of metolachlor was 36 nglL and the maximum concen- tration was 78 ng/L compared to a maximum floodwater concentration of27 ng/L (table 9). On the other hand, the peak flow at Tarboro was about 50 times greater than the long-term mean September flow, so pesticide concentrations were highly diluted. In the Neuse River at Kinston (site 28), 35 measurements of atrazine during 1994--99 had a median concentration of 20 ng/L and a maximum of 14 nglL com- pared to a maximum floodwater concentration of 10.3 ng/L (table 9), Because of concerns about fuel spills during the flooding that fol- lowed Hurricane Floyd, four water samples were collected and ana- lyzed for fuel and fuel oxygenate compounds benzene, diisopropyl PESTICIDE CONTAMINATION OF SURFACE WATERS Total annual pesticide use in the United States is about 1 billion pounds (U.S. Geological Survey. 1999), of which about 70 to 80 per- cent is for agricultural applications. Pesticides include both herbicides, which account for about 60 percent of agricultural pesticides, and insecticides, which are generally more toxic to aquatic life than herbicides. Pesticides, including agricultural pesticides, are detected in all types of settings, including urban areas (for exam- ple, Bales and others, 1999), but insecticides are more likely to be detected in high concentrations in urban streams than in other settings (U.S. Geological Survey, 1999). In streams that drain to the Albemarle and Pamlico Sounds, the most commonly detected pesticides in 1993-95 were the herbicides metolachlor, atrazine, alachlor, and prometon (Spruill and others, 1998). The highest con- centrations generally occurred in late May and early June; concen- trations then decreased through- out the summer. Consequently, if flooding had occurred earlier in the summer, the concentrations of pesticides detected in flood- waters may have been greater than were detected in Septem- ber. The greatest incidence of pesticide detection during 1993-95 occurred in the Tar River Basin (Spruill and others, 1998). During the 1999 flooding, however, the greatest occurrence of pesticides was in the Neuse River and Contentnea Creek, a major tributary to the Neuse River, Atrazine, carbaryl, meto- lachlor, diazinon, and malathion were the most commonly detected pesticides in small streams that drain developed areas of Charlotte, which is probably typical of urban areas in eastern North Carolina (Bales and others, 1999). Small streams draining residential areas had the greatest incidence of detec- tion of pesticides in Charlotte. ,. J ".' . - I ____ ^1\f. \,....~."" ' ~- '-..:1.... jl \ ~ ." If' . ' \'> "" '"",./ ' '.' \\ Ii ; ~ USGS isokinetic ",,'ater-quality sampler ~ ~ ~ ~ Two Months of Flooding in Eastern North Carolina. Scptcmber-October 1999