18.104.22.168. About Doctors Lake
- West of the St. Johns River in Clay County
- Primary Land Use: Forested
- Current TMDL reports: Nutrient – 2389 (draft), DO/Nutrient – 2410 (draft), Silver – 2389/2410
- Verified Impaired 2016 (final): Nutrients (Chlorophyll-a 2389 med), Nutrients (Total P 2389 med)
- WBID Area: 8.4 sq. mi.
- Beneficial Use: Class III F (Recreational – Freshwater)
22.214.171.124. Data sources
Result data was downloaded from the FL STORET website (DEP 2010e) and filtered based on the stations (DEP 2010f) in Doctors Lake WBIDs 2389 and 2410 (DEP 2014d) shown above. The filtered dataset was used to generate Table 2.10, with freshwater stream WQC’s reported. These should be regarded as guidelines only because Swimming pen creek (2389) is accessed as a stream, Doctors Lake (2410) is accessed as a lake and has different WQC’s.
Water quality data for Doctors Lake are shown in Table 2.10. Although average total nitrogen and total phosphorus levels were within their WQC limits, average chlorophyll-a concentrations far exceeded the WQC, particularly in summer months (Figure 2.40), and average dissolved oxygen levels are well above the SSAC. Thus, Doctors Lake has been identified as being impaired for nutrients (chlorophyll-a and total phosphorus) (DEP 2016j), and the final TMDL report to address this has been published (Magley 2009e). Elevated maximum arsenic, cadmium, copper, nickel, silver, and zinc concentrations were also measured in Doctors Lake, and as a result, EPA has published a Silver TMDL (EPA 2010a). Doctors Lake is largely used for recreational activities such as boating, fishing, and waterskiing. These activities could account for some of the copper, nickel, and zinc contamination; however, the source of the other contamination is not clear. Two small creeks that flow from swampland merge and enter the lake from the south and the lake enters the mainstem of the LSJR from the northeast through the Doctors Inlet.
Table 2.10 Water quality data for Doctors Lake.
|Dissolved Oxygen (mg/L)||34% sat. (~3.0)||0||8.02||15.54||1678||1997 - 2016|
|Total Nitrogen (mg/L)||<1.54†||0.31||1.21||3.77||954||1997 - 2015|
|Total Phosphorus (mg/L)||<0.12†||0||0.08||0.48||2479||1996 - 2016|
|Chlorophyll-a (µg/L)||<20†||0.36||28.45||198.54||1106||1997 - 2016|
|Arsenic (µg/L)||≤50||0||4.56||85.6||505||1997 - 2016|
|Cadmium (µg/L)||≤0.3||0||0.3||4.19||401||1997 - 2016|
|Copper (µg/L)||≤9.3||0||2.39||246.55||738||1997 - 2016|
|Lead (µg/L)||≤3.2||0||2.14||26.98||543||1997 - 2016|
|Nickel (µg/L)||≤52||0||3.66||117.8||319||1997 - 2016|
|Silver (µg/L)||≤0.07||0||0.3||4.38||345||1997 - 2016|
|Zinc (µg/L)||≤120||0.04||5.38||128.1||775||1997 - 2016|
|Fecal Coliform (log #/100 mL)||<2.6†||No valid data available|
|Turbidity (NTU)||<29||0.9||6.41||49||1098||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.