3.0  Bradley Creek

            The Bradley Creek watershed is of particular current interest as a principal location for Clean Water Trust Fund mitigation activities, including the purchase and renovation of Airlie Gardens by the County.  This creek is one of the most polluted in New Hanover County, particularly by fecal coliform bacteria (Mallin et al. 2000b).  Seven stations were sampled in the past year, both fresh and brackish (Fig. 3.1). 

            As with last year, turbidity was not a major problem during 2003-2004 (Table 3.1).  The standard of 25 NTU was exceeded twice at the upper north branch (November and December, 58 and 45 NTU, respectively) and once at the north branch (BC-NB) in December 2003 (37 NTU - Table 3.1).  There were only minor problems with low dissolved oxygen (hypoxia), with BC-76 having DO of less than 5.0 mg/L on two occasions and BC-CA having substandard dissolved oxygen conditions on three of seven sampling occasions (Appendix B). 

Table 3.1  Water quality parameter concentrations at Bradley Creek sampling stations, August 2003-July 2004.  Data as mean (SD) / range, fecal coliform bacteria as geometric mean / range; (for BC-CA, n = 7 months).

_____________________________________________________________________
Station            Salinity                     Turbidity            Dissolved Oxygen   Fecal coliforms
                          (ppt)                            (NTU)                         (mg/L)             (CFU/100 mL)
_____________________________________________________________________ 
BC-76             30.1 (5.0)                   5 (3)                            7.5 (2.4)                      NA
                        18.6-36.4                   0-13                            4.5-11.3          

BC-SB            8.0 (9.6)                      7 (4)                            8.0 (2.2)                      NA
                        0.1-27.3                      3-18                            3.6-11.1          

BC-SBU         0.1 (0.0)                      4 (5)                            8.1 (1.8)                      NA
                        0.1-0.1                        1-19                            4.5-11.7          

BC-NB           15.9 (13.0)                 10 (9)                          7.3 (2.1)                      NA
                        0.2-33.2                      1-37                            4.8-11.1          

BC-NBU        0.1 (0.0)                      15 (19)                        7.7 (1.1)                      NA
                        0.1-0.2                        1-58                            6.4-9.5            

BC-CR           0.1 (0.0)                      3 (3)                            7.9 (0.7)                      NA
                        0.1-0.1                        0-8                              6.5-9.1            

BC-CA           0.1 (0.0)                      7 (7)                            6.4 (2.7)                      807
                        0.1-0.2                        1-22                            4.3-11.4                      60-6000
_____________________________________________________________________ 

Only BC-CA was sampled for fecal coliform concentrations last year, with elevated counts exceeding the State standard of 200 CFU/100 mL occurring during six of seven collections for an 86% exceedence rate (Table 3.1).  We consider BC-CA to have poor water quality in terms of fecal coliform counts (Appendix B).

            Nitrate concentrations were highest at stations BC-CR, BC-SBU (upper south branch) and BC-NBU.  Nitrate decreased slightly in the south branch in comparison to the previous year.   Ammonium was elevated at BC-CA, but low at other locations.  The highest orthophosphate levels were found at BC-CA, with relatively low orthophosphate levels at the rest of the stations (Table 3.2).  Bradley Creek did not host excessive algal blooms in 2003-2004, except for a minor bloom in June at BC-SB (24.3 mg/L) and a major bloom (40.3 mg/L) in June at BC-CA (Table 3.2). 

Table 3.2.  Nutrient and chlorophyll a data at Bradley Creek sampling stations, August 2003-July 2004.  Data as mean (SD) / range, nutrients in mg/L, chlorophyll a as mg/L.
_____________________________________________________________________
Station            Nitrate                        Ammonium                Orthophosphate        Chlorophyll a
_____________________________________________________________________
BC-76             0.015 (0.012)             0.023 (0.015)             0.012 (0.006)            1.2 (0.7)
                        0.003-0.042               0.008-0.049               0.005-0.023               0.3-2.2

BC-SB            0.070 (0.060)             0.024 (0.013)            0.013 (0.010)             5.1 (7.3)
                        0.003-0.169               0.008-0.041               0.005-0.044               0.6-24.7

BC-SBU         0.083 (0.033)             NA                              0.011 (0.011)             2.3 (3.1)
                        0.054-0.171                                                   0.006-0.044               0.3-11.2 

BC-NB           0.042 (0.051)              0.029 (0.022)            0.011 (0.008)             3.7 (3.6)
                        0.003-0.156               0.008-0.072               0.003-0.028               0.6-10.9 

BC-NBU        0.087 (0.018)             NA                                0.005 (0.005)            0.5 (0.4)
                        0.062-0.123                                                   0.002-0.020               0.1-1.2 

BC-CR           0.274 (0.047)             NA                               0.007 (0.006)             0.4 (0.4)
                        0.154-0.317                                                   0.002-0.024               0.1-1.5

BC-CA           0.085 (0.109)             0.121 (0.055)             0.019 (0.016)             11.2 (14.3)
                        0.013-0.330               0.040-0.190               0.005-0.040               1.5-40.3
_____________________________________________________________________