2.7.14. Greenfield Creek

2.7.14.1. About Greenfield Creek

Figure 2.43 Greenfield Creek (WBID 2240A/B) with sanitary sewer overflows reported by JEA in 2019 (JEA 2019b).
Figure 2.43 Greenfield Creek (WBID 2240A/B) with sanitary sewer overflows reported by JEA in 2019 (JEA 2019b).
  • West of the Intracoastal Waterway
  • Primary Land Use: Residential
  • Current TMDL reports:
    Fecal Coliform with BMAP (2010), Mercury
  • Not included in 2016 Verified List of Impaired Waters
  • WBID Area: 2.9 sq. mi.
  • Beneficial Use: Class III F/M (2240A Recreational – Marine, 2240B Recreational – Freshwater)

2.7.14.2. Data sources

Data were downloaded from the FL STORET and WIN websites (DEP 2010f; DEP 2018c) and filtered based on the stations (DEP 2010g) in Greenfield Creek WBID 2240A (marine) and 2240B (freshwater) (DEP 2014c) shown above. The filtered dataset reflects water column concentrations and was used to generate Table 2.15.

2.7.14.3. Discussion

Water quality data for Greenfield Creek are shown in Table 2.15. Average phosphorus levels were historically higher than the recently updated WQC (DEP 2015c; DEP 2016e; DEP 2016k), but data from 2017 through 2019 indicate that average concentrations of phosphorus and dissolved oxygen were within acceptable limits.  Average chlorophyll-a concentrations decreased in 2018 but jumped up in 2019 in both the marine and freshwater regions of Greenfield Creek, exceeding the WQC.  Dissolved oxygen was removed from the verified impaired list (DEP 2016j) in Greenfield Creek. Greenfield Creek was verified impaired for mercury (DEP 2016j), but this has been addressed in the statewide mercury TMDL already in place (DEP 2013c).

A TMDL report (Wainwright and Hallas 2009a) was released to address fecal coliform, and a BMAP for Greenfield Creek (DEP 2010a) was legally adopted in August 2010. It describes sources of fecal coliform in the watershed, and completed and ongoing activities conducted by state and local agencies that are anticipated to reduce fecal coliform loading in the tributary. The Greenfield Creek watershed does not contain any permitted point sources for industrial wastewater. It contains the Girvin Road Landfill, which has been inactive since 1992; this landfill received not only solid waste, but sludge from the Neptune Beach Sewage Treatment Plant. The watershed also contains numerous outfalls for stormwater discharge. The last Annual Progress Report for this BMAP was published in 2016 and listed 20 active, ongoing projects underway by FDOT and JEA to address the BMAP in the Greenfield Creek watershed (DEP 2017c). FDEP reported improvement in the frequency of fecal coliform exceedances in the freshwater segment of Greenfield Creek, but the last fecal coliform measurements in Greenfield Creek before 2018 date back to 2008.  Recent measurements indicate ongoing issues with fecal coliform concentrations. Additional information about fecal coliform in the tributaries can be found in Section 2.6 and Table 2.2.  In 2018, FDEP piloted microbial source tracking strategies in selected impaired waterbodies.  They found that the strategies used could be used to narrow down areas suspected of containing sources that actively contribute fecal indicating bacteria to water in order to identify and remediate them, but this work is resource-intensive.  The source of fecal coliform in Greenfield Creek was unknown (DEP 2019a).

Historical water quality data for these parameters in Greenfield Creek are available in previous versions of the River Report.

Table 2.15 Water quality data for Greenfield Creek.

 Water QualityAverage and Number of Samples º
ParameterCriteria201720182019
Dissolved Oxygen (mg/L)≥34% sat. (≥3.0) FWNot available7.10
(0 of 15 samples)
5.81
(0 of 6 samples)
≥4.0 SW4.87
(0 of 4 samples)
4.27
(5 of 14 samples)
5.80
(0 of 10 samples)
Total Nitrogen (mg/L)<1.54Not available0.92
(0 of 11 samples)
0.71
(0 of 12 samples)
Total Phosphorus (mg/L)<0.120.07
(0 of 4 samples)
0.07
(0 of 12 samples)
0.08
(1 of 10 samples)
Chlorophyll-a (µg/L)<20 FWNot available2.42
(0 of 7 samples)
27.4
(2 of 4 samples)
<5.4 SW6.58
(3 of 4 samples)
1.97
(1 of 5 samples)
7.65
(3 of 6 samples)
Arsenic (¬µg/L)≤50 Not availableNot available2.35
(0 of 10 samples)
Cadmium (µg/L)<0.3 FWNot availableNot available0.03
(0 of 4 samples)
<8.8 SWNot availableNot available0.05
(0 of 6 samples)
Copper (µg/L)<9.3 FWNot availableNot available2.41
(0 of 4 samples)
<3.7 SWNot availableNot available0.80
(0 of 6 samples)
Lead (µg/L)<3.2 FWNot availableNot available0.33
(0 of 4 samples)
<8.5 SWNot availableNot available0.80
(0 of 6 samples)
Nickel (µg/L)<52 FWNot availableNot available0.81
(0 of 4 samples)
<8.3 SWNot availableNot available1.50
(0 of 6 samples)
Silver (µg/L)<0.07 FWNot availableNot available0.02
(0 of 4 samples)
<0.92 SWNot availableNot available0.03
(0 of 6 samples)
Zinc (µg/L)<120 FWNot availableNot available5.00
(0 of 4 samples)
<86 SWNot availableNot available8.33
(0 of 6 samples)
Fecal Coliform (CFU/100 mL)<400Not available760
(10 of 26 samples)
540
(2 of 7 samples)
Turbidity (NTU)<298.45
(0 of 4 samples)
5.11
(0 of 12 samples)
6.40
(0 of 10 samples)
Note: Hardness-dependent freshwater criteria for cadmium, copper, lead, nickel, and zinc were generated based on a hardness concentration of 100 mg/L.
° = 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.