Upper and Lower Cape Fear

    Within the Wilmington City limits drainage directly to the Cape Fear River (CFR) was sampled at one location each in the Upper and Lower Cape Fear Watersheds. The stream draining the Upper CFR was sampled behind the Wilmington Police Station between 2^nd and 3^rd Streets (Fig. 11.1). Concentrations of most physical, chemical and biological constituents were low to moderate except for nitrate (Table 11.1). Nitrate concentrations in this stream were the highest in any of the City or County drainage basins. The source of this nitrate is currently not defined, but additional spot samples taken in September and October showed slightly higher concentrations near the 4^th St. bridge. In September nitrate levels were 2.4 mg/L at 4^th St. compared with 1.7 mg/L at UCF-PS, and in October nitrate levels were 2.3 mg/L at 4^th St. compared with 1.8 mg/L at UCF-PS. We note that overall nitrate decreased from 1997-98 to 1998-99, but fecal coliform counts increased. The geometric mean was 259 CFU/100 mL for the past year, in excess of the state standard of 200 CFU/100 mL.

    Drainage from the Lower CFR was sampled from the stream draining Greenfield Lake (Fig. 11.2). Processing within the lake served to keep concentrations of most constituents relatively low (Table 11.1). Average fecal coliforms, turbidity, and chlorophyll a were all below state water quality standards during the sampling period.

Table 11.1   Water quality summary statistics (mean (standard deviation) / range) for Wilmington Upper (UCF) and Lower (LCF) Cape Fear Watersheds.
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Station            DO (mg/L)     Turbidity (NTU)         TSS (mg/L)         Fecal col (CFU/100 mL)
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UCF                 8.0 (0.8)             3.4 (3.7)                 1.5 (0.7)                     259
                         6.9-9.3               0.1-12.2                 0.5-3.0                       30-1280

LCF                 8.4 (2.5)             4.5 (4.4)                 3.5 (2.6)                     71
                         4.2-13.5             1.2-13.1                 1.5-11.0                     25-205
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                    Nitrate (mg/L)         Ammonium (mg/L)         Orthophosphate (mg/L)
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UCF             2.227 (0.617)             0.017 (0.016)                     0.030(0.013)
                     1.400-3.400                0.005-0.050                       0.005-0.050

LCF             0.011 (0.016)             0.036 (0.047)                     0.031 (0.020)
                     0.005-0.060               0.005-0.150                       0.005-0.070
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