2.7.4. Black Creek

2.7.4.1. About Black Creek

Figure 2.26
Figure 2.27 The Black Creek Tributary (WBID 2415A/B/C).
  • West of the St Johns River at the Clay/Duval county line
  • Primary Land Use: Forested
  • Current TMDL reports: Lead – 2415B, 2415C
  • Verified Impaired 2016 (final): None
  • WBID Area: 15.4 sq. mi.
  • Beneficial Use: Class III F (Recreational – Freshwater)

2.7.4.2. Data sources

Result data were downloaded from the FL STORET website (DEP 2010e) and filtered based on the stations (DEP 2010f) in Black Creek WBID 2415A/B/C (DEP 2014d) shown above. The aggregate (all three WBIDs) filtered dataset was used to generate Table 2.5 and Figures 2.28 and 2.29.

2.7.4.3. Discussion

Water quality data for Black Creek are shown in Table 2.5. As compared to other tributaries in the LSJRB, Black Creek is less impacted for the majority of the assessed water quality parameters. Lead has been identified as impaired in Black Creek and a TMDL report was published in 2009 (Lewis and Mandrup-Poulsen 2009) to address this issue.

Table 2.5 Water quality data for Black Creek.
Water QualityConcentrationSampling
ParameterCriteria (FW)LowAverageHighSamplesPeriod
Dissolved Oxygen (mg/L)34% sat. (~3.0)0.56.1912.455701997 - 2016
Total Nitrogen (mg/L)<1.540.070.72.113741997 - 2015
Total Phosphorus (mg/L)<0.120.030.10.518111997 - 2016
Chlorophyll-a (µg/L)<2003.2953.294381997 - 2016
Arsenic (µg/L)≤5001.319.742861997 - 2016
Cadmium (µg/L)≤0.300.0813161997 - 2016
Copper (µg/L)≤9.301.4122.823761997 - 2016
Lead (µg/L)≤3.200.86.783521997 - 2016
Nickel (µg/L)≤5201.220.553591997 - 2016
Silver (µg/L)≤0.0700.138.442511997 - 2016
Zinc (µg/L)≤1200.144.9656.74041997 - 2016
Fecal Coliform (log #/100 mL)<2.60.181.422.96982002 - 2013
Turbidity (NTU)<290.86.513684921997 - 2016
Note: Hardness-dependent freshwater criteria for cadmium, copper, lead, nickel, and zinc were generated based on a hardness concentration of 100 mg/L.
FW = freshwater; SW = saltwater (marine). Values denoted with (*) indicate a proposed criterion, which has not yet been adopted.
Values denoted with (†) are reference values based on EPA criteria (EPA 2010b), but the water body is not regulated by this standard.

 

Figure 2.27
Figure 2.28 Monthly dissolved oxygen concentrations (data from 1997-2014) in Black Creek. Data are presented as a box-and-whiskers plot with the green boxes indicating the median ± 25% (middle 50% of the data) and horizontal lines indicate the median values. Blue whiskers indicate the minimum and maximum values in the data set.
Figure 2.28
Figure 2.29 Monthly chlorophyll-a concentration (μg/L), based on data from 1997 through 2014 in Black Creek.

The maximum cadmium concentrations detected were more than threefold higher than the freshwater criterion (Table 2.5 above). In periods of higher salinity, elevated copper and nickel concentrations may be problematic, as they were detected at levels above WQC. The maximum silver concentration detected in Black Creek was more than 100 times the freshwater criterion and also substantially elevated above the SW criterion. The concentrations of silver detected have the potential for causing toxic effects to aquatic life in this area.