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 Barnards and Motts Creeks.  In 2004 we collected data at a station located on Barnards Creek at River Road (BNC-RR) that drains part of this area (Fig. 2.1).  Sampling at two other sites, BNC-CB site near Carolina Beach Road and BNC-TR at Titanium Rd. has been discontinued. 

BNC-RR had average salinity of 5.7 ppt with a range of 0.1-21.4 ppt.  This station had dissolved oxygen levels below 5 mg/L (but above 4.0 mg/L) from May through September.  Concentrations of nutrients (total nitrogen, ammonium, and total phosphorus) were among the highest in the Wilmington area (Table 2.1).  Turbidity on average was relatively high (21 NTU), and exceeded the state standard for estuarine waters of 25 NTU three times out of the seven sampling periods.  Total suspended solids concentrations were the highest among area creeks, particularly May through July, but there were no algal bloom problems (Table 2.1).  BOD5 was sampled seven times at BNC-RR last year, yielding a median of 1.1 and a mean of 1.3 mg/L, which was down from the BOD5 concentrations found in previous years (Mallin et al. 2003; 2004).  Median and mean BOD20 in 2004 was 5.5 and 5.9 mg/L, respectively, a slight decrease from the previous year.   Fecal coliform counts exceeded the state standard on only one of seven occasions for a 14% non-compliance rate, an improvement over the previous two years.  Thus, this station can be considered impaired by turbidity and low dissolved oxygen, with comparatively high nutrient concentrations as well. 

Table 2.1. Mean and standard deviation of water quality parameters in Barnards Creek watershed, January - September 2004. Fecal coliforms as geometric mean; N/P ratio as median (n = 7 for all parameters).

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Parameter                                          BNC-RR         
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DO (mg/L)                                          6.1 (3.0)            
Turbidity (NTU)                                  21 (8)    
TSS (mg/L)                                        24.7 (8.5)         
Nitrate (mg/L)                                    0.140 (0.138) 
Ammon. (mg/L)                                 0.247 (0.187) 
TN (mg/L)                                          1.464 (0.374) 
Phosphate (mg/L)                             0.042 (0.043) 
TP (mg/L)                                           0.127 (0.047) 
N/P molar ratio                                  29.9                           
Chlor. a (mg/L)                                   3.5 (3.1)           
BOD5                                                 1.3 (0.6)
BOD20                                               5.9 (1.9)
Fec. col.(/100 mL)                            121                  
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