2.0  Barnards Creek

The water quality of lower Barnard’s Creek is becoming an important issue as single family and multifamily housing construction has occurred upstream of Carolina Beach Rd. in the St. Andrews Dr. area; another major housing development is planned for the area east of River Road and between Barnard’s and Mott’s Creeks.  We collected data at a station located on Barnard’s Creek at River Road (BNC-RR) that drains part of this area.  The BNC-TR site in Barnard’s Creek watershed drains a wooded area and had been considered a control site for nutrients and physical parameters.  However, we also note that the control is now near an active road and condominium construction area on Titanium Road, or Independence Road Extension (Fig. 2.1), and this can no longer be considered a background site.  Thus, sampling at this site was stopped after December 2002.  The BNC-CB site is near Carolina Beach Road and drains an area hosting construction activities.  BNC-TR exceeded the state fecal coliform standard of 200 CFU/100 mL on 50% of the sampling trips and BNC-CB exceeded the standard on 75% of the trips (Table 2.1; Appendix B).  Both of these sites were thus significantly impaired by elevated fecal coliform counts during 2002-2003.  Total nitrogen (TN) showed an increase over 2001-2002, but chlorophyll a levels were unremarkable at these sites, and turbidity was low.

We report here water quality data from the estuarine site on River Road.  BNC-RR had average salinity of 5.1 ppt with a range of 0.1-21.4 ppt.  Lower Barnard’s Creek had dissolved oxygen levels below 5 mg/L on five occasions out of 11 samples in 2002-2003, as compared with two out of twelve in 2001-2002.  Concentrations of nutrient species did not increase over the 2001-2002 values at this station, except for total nitrogen.  Turbidity on average was high (44 NTU), and exceeded the state standard for estuarine waters of 25 NTU five times, same as the 2001-2002 year.  Total suspended solids concentrations were generally high, particularly in August and September of 2002.  BOD5 was sampled 11 times at BNC-RR last year, yielding a median of 1.5 and a mean of 1.4 mg/L, which was down from the BOD5 concentrations found in the 2001-2002 study (Mallin et al. 2003).  Median and mean BOD20 in 2002-2003 was 5.9 and 6.0 mg/L, respectively, a decrease from the previous year.   Fecal coliform counts exceeded the state standard two of 11 occasions for a 18% non-compliance rate, an improvement over the previous year’s 33% non-compliance rate.  Thus, this station can be considered impaired by low dissolved oxygen, turbidity and fecal coliform loading. 

Table 2.1. Mean and standard deviation of water quality parameters in Barnard’s Creek watershed,
August 2002-September 2003. Fecal coliforms as geometric mean; N/P ratio as median.
BNC-TR was only sampled four times.
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Parameter                  BNC-TR                        BNC-CB                    BNC-RR        
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DO (mg/L)                  4.8 (1.7)                         6.9 (1.5)                   6.5 (2.7)      

Turbidity (NTU)          90 (172)                         12 (12)                       44 (55)       

TSS (mg/L)                13.8 (14.8)                     5.4 (3.9)                  38.5 (53.7)    

Nitrate (mg/L)            0.060 (0.080)             0.069 (0.051)            0.215 (0.196) 

Ammon. (mg/L)         0.109 (0.051)             0.092 (0.058)            0.123 (0.059) 

TN (mg/L)                  1.317 (0.284)              0.894 (0.352)            1.417 (0.398) 

Phosphate (mg/L)    0.050 (0.051)              0.034 (0.073)            0.067 (0.041) 

TP (mg/L)                   0.081 (0.056)             0.087 (0.103)            0.126 (0.040) 

N/P molar ratio               22.1                             33.4                        12.6                           

Chlor. a (mg/L)              0.8 (0.1)                    2.9 (3.1)                      4.9 (3.9)     

Fec. col.(/100 mL)           307                              505                         96                     
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