220.127.116.11. About Dunns Creek/Crescent Lake
- East of the St. Johns River in Flagler County
- Primary Land Use: Forested/Wetlands
- Current TMDL reports: Mercury – 2606B, Nutrients – 2606B (draft)
- Verified Impaired 2016 (final): Fecal Coliform (2606A low), Nutrients (Chlorophyll-a, Total P 2606B med)
- WBID Area: 585 sq. mi.
- Beneficial Use: Class III F (Recreational – Freshwater)
18.104.22.168. Data sources
Result data was downloaded from the FL STORET website (DEP 2010e) and filtered based on the stations (DEP 2010f) in the Dunns Creek/Crescent Lake WBIDs 2606A/B (DEP 2014d) shown above. The filtered dataset was used to generate Table 2.11, with freshwater stream WQC’s reported. These should be regarded as guidelines only because Dunns Creek (2606A) is accessed as a stream, Crescent Lake (2606B) is accessed as a lake and has different WQC’s.
Water quality data for Dunns Creek/Crescent Lake are shown in Table 2.13. This tributary is a significant non point-source contributor to nutrient levels in the St. Johns River (Magley and Joyner 2008). There is a significant variation of dissolved oxygen going upstream of the creek and into the lake as evidenced by the wider spread of values in Figure 2.41.
Dunns Creek (WBID 2606A) was identified as being impaired for mercury, based on elevated levels of mercury in fish tissue, however this is being delisted (DEP 2016h) as it has been addressed by the statewide mercury TMDL (DEP 2013e). In addition, a TMDL for Nutrients was recently drafted (Bubel 2015) for Crescent Lake based on its Trophic State Index (TSI), calculated from the total nitrogen (TN), total phosphorus (TP), and chlorophyll-a levels. Crescent Lake is listed on the revised verified list for chlorophyll-a and total phosphorus (DEP 2016j).
Table 2.11 Water quality data for Dunns Creek/Crescent Lake.
|Dissolved Oxygen (mg/L)||34% sat. (~3.0)||0||7.51||16.93||2475||1997 - 2016|
|Total Nitrogen (mg/L)||<1.54†||0.53||1.3||3.24||956||1997 - 2015|
|Total Phosphorus (mg/L)||<0.12†||0||0.07||0.51||2871||1997 - 2016|
|Chlorophyll-a (µg/L)||<20†||0.15||19.89||198.11||1431||1997 - 2016|
|Arsenic (µg/L)||≤50||0||1.5||5.77||439||1997 - 2016|
|Cadmium (µg/L)||≤0.3||0||0.07||1.02||386||1997 - 2016|
|Copper (µg/L)||≤9.3||0||1.43||392.9||716||1997 - 2016|
|Lead (µg/L)||≤3.2||0||0.79||5.36||461||1997 - 2016|
|Nickel (µg/L)||≤52||0||1.11||53.26||359||1997 - 2016|
|Silver (µg/L)||≤0.07||0||0.13||1.16||345||1997 - 2016|
|Zinc (µg/L)||≤120||0||3.35||133.7||764||1997 - 2016|
|Fecal Coliform (log #/100 mL)||<2.6†||-0.3||0.65||3.68||124||1998 - 2013|
|Turbidity (NTU)||<29||0.65||5.47||35.4||1429||1997 - 2016|
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.