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much less than the maximum con- centrations measured during that period. However, the ammonia concentration measured on Septem- ber 23, 1999, at the Cape Fear River at Lock I was the highest ammonia concentration measured at the site during 1990-99. Organic nitrogen, total phosphorus, and orthophos- phorus concentrations measured in floodwaters were approximately equal to median concentrations measured from January 1990 to August 1999 (table 8), Nitrate con- centrations measured in Hurricane Floyd floodwaters were low com- pared to previous measurements made from January 1990 to August 1999 (table 8). In the Tar-Pamlico River Basin, concentrations of nitrate ranged from below detection (<0.005 mg/L) to 0.073 mg/L (Tar River at Louisburg) except at Tar River at Tar River, which had a concentration of 0.11 mg/L on thc falling side ofthc peak streamflow. Ammoniaconcentrations ranged from below detection (<0.002 mg/L) to 0.150 mg/L at site 9 (Tar River below Tar River Reservoir). Most of the nitrogen at the Tar- Pamlico River Basin sites occurred as organic nitrogen, Organic nitro- gen concentrations ranged from 0.5 to 1.0 mg/L. These concen- trations generally were greatcr than the 75-percentile concentration determined from previous records (Hamed and others, 1995; table 8). In the Neuse River Basin, nitrite plus nitrate concentrations ranged from below detection (<0.05 mg/L) to 0.31 mg/L. Ammonia concentra- tions ranged from <0.02 to 0.171 mg/L. Both the maximum ammonia and maximum nitrate con- centrations occurred on thc fall ing Flooded hog farm side of the peak at Clayton (site 22), One of the highest ammo- nia concentrations \vas measured during the peak streamflow at Crabtree Crcek at Raleigh (0.129 mg/L, site 2 I )-a small urban tributary to the Neuse River. The ammonia concentration measured near the streamflow peak in Contentnca Creek at Hookerton (site 31), a Neuse River tributary that drains a primarily agricultural basin, was <0.02 mg/L; the nitrate concentration also was quite low (<0.05 mgIL) compared with typical nitrate con- centrations thcre (median is 0.69 mg/L; table 8). As in the Tar- Pamlico Basin, most of the nitrogen at the Neuse River Basin sites occurred as organic nitrogen; concentra- tions ranged from 0,5 to 1.7 mg/L with the maxi- mum concentration occurring at Fort Barn- well (site 32). This concentration was ncarly double the con- centrations measured at Kinston (site 28) during the flooding. Higher \:Vastewater-treatment facility in Greenville, N.C. Two Months of Flooding in Eastem Nonh Carolina, September-October 1999 ~ w o u z