2.7.19. Mill Creek

2.7.19.1. About Mill Creek

Figure 2.51
Figure 2.52 The Mill Creek Tributary (WBID 2460).
  • East of the St. Johns River feeding into Sixmile Creek
  • Primary Land Use: Wetlands/forest
  • Current TMDL reports: Fecal Coliform, DO/Nutrient
  • Verified Impaired 2016 (final): Iron (high)
  • WBID Area: 11.6 sq. mi.
  • Beneficial Use: Class III F (Recreational – Freshwater)

2.7.19.2. Data sources

Result data was downloaded from the FL STORET website (DEP 2010e) and filtered based on the stations (DEP 2010f) in Mill Creek WBID 2460 (DEP 2014c) shown above. The filtered dataset was used to generate Table 2.17.

2.7.19.3. Discussion

Water quality data for Mill Creek are shown in Table 2.17. Historically, the fecal coliform level, averaged over all the stations in Mill Creek, was above the WQC of 400 colony-forming-units (CFU) per 100 mL. Thus, a TMDL for fecal coliform was published in 2009 (Rhew 2009b). (Note: the data analyses in the TMDL are based on different criteria than those used in this report). However, the last fecal coliform measurements available in STORET date back to 2008.

In addition, Mill Creek has been identified as impaired for dissolved oxygen and associate nutrients and a TMDL addressing this was published in 2010 (Magley 2010). Iron has been added in the recent revised verified impaired list (DEP 2016j) for Mill Creek and is potentially a natural condition, common in Florida blackwater streams such as this.

Water quality data for Mill Creek are extremely limited in STORET, with only two measurements performed in 2017.  No recent measurements were available in STORET between 2015 and 2017 for the following parameters:

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

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

Table 2.17 Water quality data for Mill Creek (2015-2017).

 Water QualityAverage and Number of Samples º
ParameterCriteria201520162017
Dissolved Oxygen (mg/L)≥34% sat.
(≥3.0) FW
No dataNo data1.45
(0 of 2 samples)
Nitrate-nitrite N (mg/L)§§No dataNo data0.40
(2 samples)
Total Phosphorus (mg/L)<0.12No dataNo data0.18
(2 of 2 samples)
Chlorophyll-a (µg/L)<20 FWNo dataNo data1.45
(0 of 2 samples)
Turbidity (NTU)<29No dataNo data4.40
(0 of 2 samples)
Note: Hardness-dependent freshwater criteria for cadmium, copper, lead, nickel, and zinc were generated based on a hardness concentration of 100 mg/L.
º = Number of samples below WQC for Dissolved Oxygen, Number of samples above WQC 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.
§ = No water quality criterion has been established for Nitrate-Nitrite nitrogen. No Total Nitrogen data were available in STORET for 2015-2017.