2.7.16.1. About the Intracoastal Waterway
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- Near the mouth of the St. Johns River
- Primary Land Use: Marsh/Wetland (Land Cover)
- Current TMDL reports: None
- 2022 Verified Impairment for Fecal coliform (Enterococci) and Iron
- WBID Area: 23.9 sq. mi.
- Beneficial Use: Class III M
(Recreational – Marine)
2.7.16.2. Data sources
Data were historically downloaded from the FL STORET website (DEP 2010f), with recent data downloaded from WIN WAVES (DEP 2022f). Data were filtered based on the stations in the Intracoastal Waterway (ICW) WBID 2205C (DEP 2023b) shown above. The filtered dataset reflects water column concentrations and was used to generate Table 2.21.
2.7.16.3. Discussion
Water quality data for the ICW are shown in Table 2.21. The ICW does not appear to 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 2013c). Limited fecal indicator bacteria measurements were available prior to 2019, but the average fecal indicator bacteria levels in 2020-2022 all exceeded the WQC; the ICW is verified impaired for fecal coliform in 2022 (DEP 2022). The ICW is also verified impaired for iron concentrations in 2022 (DEP 2022). Iron concentrations were at the WQC in 2022.
Historical water quality data for the Intracoastal Waterway are available in previous versions of the River Report.
Table 2.21 Water quality data for the Intracoastal Waterway.
| Water Quality | Average and Number of Samples º | |||
|---|---|---|---|---|
| Parameter | Criteria (SW) | 2020 | 2021 | 2022 |
| Dissolved Oxygen (mg/L) | ≥4.0 | 5.97 (0 of 31 samples) | 5.99 (3 of 14 samples) | 7.03 ± 0.34 (0 of 12 samples) |
| Total Nitrogen (mg/L) | <1.54‡ | Not available | Not available | 0.57 ± 0.08 (0 of 4 samples) |
| Total Phosphorus (mg/L) | <5.4‡ | 0.09 (1 of 14 samples) | 0.03 (0 of 8 samples) | 0.08 ± 0.01 (0 of 4 samples) |
| Chlorophyll-a (µg/L) | <11‡ | 2.62 (0 of 14 samples) | 0.86 (0 of 7 samples) | 3.18 ± 0.70 (0 of 4 samples) |
| Arsenic (µg/L) | ≤50 | 8.8 (0 of 13 samples) | 20.00 (0 of 2 samples) | 2.50 ± 0.01 (0 of 4 samples) |
| Cadmium (µg/L) | ≤8.8 | 0.36 (0 of 13 samples) | 0.50 (0 of 2 samples) | 0.20 ± 0.05 (0 of 4 samples) |
| Copper (µg/L) | ≤3.7 | 2.52 (5 of 13 samples) | 5.50 (2 of 2 samples) | 2.66 ± 0.09 (0 of 4 samples) |
| Iron (mg/L) | ≤0.3 | 0.4 (9 of 13 samples) | 0.11 (0 of 2 samples) | 0.30 ± 0.05 (3 of 4 samples) |
| Lead (µg/L) | ≤8.5 | 0.52 (0 of 13 samples) | 0.50 (0 of 2 samples) | 0.29 ± 0.04 (0 of 4 samples) |
| Nickel (µg/L) | ≤8.3 | 1.17 (1 of 13 samples) | 1.00 (0 of 2 samples) | 0.62 ± 0.13 (0 of 4 samples) |
| Silver (µg/L) | ≤0.92* | 1.77 (1 of 13 samples) | 0.50 (0 of 2 samples) | 0.19 ± 0.06 (0 of 4 samples) |
| Zinc (µg/L) | ≤86 | 0.35 (0 of 13 samples) | 5.00 (0 of 2 samples) | 3.75 ± 1.25 (0 of 4 samples) |
| Fecal Indicator Bacteria (Enterococci) (CFU/100 mL) | E. coli <410 | 630 (3 of 7 samples) | 1610 (3 of 6 samples) | 3330 ± 1978 (3 of 3 samples) |
| Enterococci <130 | 315 (1 of 1 samples) |
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| Turbidity (NTU) | <29 | 6.22 (0 of 13 samples) | 2.56 (0 of 1 sample) | 7.45 ± 1.75 (0 of 4 samples) |
° = Number of samples below Water Quality Criteria for Dissolved Oxygen; Number of samples above Water Quality Criteria for all other parameters.
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.