2.7.27. Sixmile Creek

2.7.27.1. About the Sixmile Creek

Figure 2.61
Figure 2.62 The Sixmile Creek Tributary (WBID 2411).
  • East of the St. Johns River in St. Johns County
  • Primary Land Use: Forested/Wetland
  • Current TMDL reports: Fecal Coliform, Mercury
  • Verified Impaired 2016 (final): None
  • WBID Area: 59.5 sq. mi.
  • Beneficial Use: Class III F (Recreational – Freshwater)

2.7.27.2. Data sources

Result data were downloaded from the FL STORET and WIN websites (DEP 2010f; DEP 2018h) and filtered based on the stations (DEP 2010g) in the Ribault River WBID 2224 (DEP 2014c) shown above. No water quality data for the selected parameters discussed below for the Ribault River were available in STORET for 2015-2017.

2.7.27.3. Discussion

Water quality data for the Ribault River are presented in Table 2.26. No water quality data were available in STORET for the Ribault River between 2012 and 2017, and the last measurements of metals date back to 2007.  The average total phosphorus concentration is near the WQC.  The Ribault River is located in a highly residential area and has historically been a contributor to elevated levels of phosphorus found in the tributary. High levels of chlorophyll-a were measured previously and again in 2018 (although the average did not exceed the WQC), but Ribault River has not been designated impaired (DEP 2016h). The Ribault River has been added to the verified impaired list for iron (DEP 2016j).

Historical fecal coliform levels, averaged over all the sampling sites in the Ribault River, were elevated. A TMDL report for fecal coliform in the Ribault River was published in 2006 (Wainwright 2006a), and a BMAP is under development. (Note: the data analyses in the TMDL are based on different criteria than that used in this report).  In 2014, the City of Jacksonville implemented a monitoring program for the Ribault River as part of a bacteria pollution control plan in concert with efforts related to stormwater management (COJ 2017).  Fecal coliform measurements from 2018 show elevated levels, with over half of the measurements exceeding the WQC.

No recent measurements were available in WIN or STORET between 2016 and 2018 for the following parameters:

  • Arsenic
  • Cadmium
  • Copper
  • Lead
  • Nickel
  • Silver
  • Zinc

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