2.7.16. Intracoastal Waterway

2.7.16.1. About the Intracoastal Waterway

Figure 2.48
Figure 2.49 The Intracoastal Waterway Tributary (WBID 2205C).
  • Near the mouth of the St. Johns River
  • Primary Land Use: Marsh/Wetland (Land Cover)
  • Current TMDL reports: Mercury
  • Verified Impaired 2016 (final): Fecal Coliform (low), Iron (med)
  • WBID Area: 23.9 sq. mi.
  • Beneficial Use: Class III M (Recreational – Marine)

2.7.16.2. Data sources

Result data were downloaded from the FL STORET website (DEP 2010e) and filtered based on the stations (DEP 2010f) in the Intracoastal Waterway (ICW) WBID 2205C (DEP 2014d) shown above. The filtered dataset was used to generate Table 2.14.

2.7.16.3. Discussion

Water quality data for the ICW are shown in Table 2.17. All parameters listed are within normal limits except for slightly elevated copper, phosphorus and chlorophyll-a. Based on this data the ICW is relatively healthy and does not provide a significant nutrient load to the St. Johns River. The Intracoastal Waterway was identified as being impaired for mercury, based on elevated levels of mercury in fish tissue, which is addressed by the statewide mercury TMDL (DEP 2013e). The Intracoastal Waterway was also identified as being impaired for fecal coliform and for iron (DEP 2016j).

Table 2.17 Water quality data for the Intracoastal Waterway.
Water QualityConcentrationSampling
ParameterCriteria (FW)LowAverageHighSamplesPeriod
Dissolved Oxygen (mg/L)?4.03.56.3911.052212002 - 2015
Total Nitrogen (mg/L)<1.540.10.784.48782007 - 2012
Total Phosphorus (mg/L)<0.120.020.10.281212000 - 2012
Chlorophyll-a (µg/L)<110.434.5323852007 - 2015
Arsenic (µg/L)≤501.266.7413.75242007 - 2015
Cadmium (µg/L)≤8.800.080.39372007 - 2015
Copper (µg/L)≤3.702.498242007 - 2015
Lead (µg/L)≤8.500.563.62332007 - 2015
Nickel (µg/L)≤8.300.461.25372007 - 2015
Silver (µg/L)≤0.92*00.090.76372007 - 2015
Zinc (µg/L)≤861.517.669332007 - 2015
Fecal Coliform (log #/100 mL)<2.60.482.414.59791999 - 2012
Turbidity (NTU)<291.88.361.11822007 - 2015
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.