WWALS Summary of FDEP chemical and biological tracers, Withlacoochee and Suwannee Rivers 2020-08-05

Here are the chemical tracer and DNA marker test results by the Florida Department of Environmental Protection (FDEP) that WWALS has frequently mentioned, for example in Current Situation of Water Quality Testing, Suwannee River Basin 2020-08-02.

Below, please also find a summary of those results by WWALS Science Committee Chair Dr. Thomas Potter.

[Human and Ruminant DNA markers]
Human and Ruminant DNA markers

Thanks to Katrina Yancey of FDEP for sending the data, and for acknowledging that FDEP has no objection to WWALS publishing it. I asked FDEP for whatever they wanted to include, and this is what they sent:

“Thank you for asking, we recently set up our new site so it may be helpful to state that more information may be found at DEP’s webpage for the Suwannee River Basin Sampling Locations (https://floridadep.gov/dear/watershed-monitoring-section/content/suwannee-river-basin-sampling-locations).”

The actual data is on the WWALS website.

WWALS Summary of FDEP chemical and biological tracer measurements
on Withlacoochee and Suwannee River samples

Dr. Thomas Potter, WWALS Science Committee Chair

After Valdosta’s raw sewage spill in early December 2019, WWALS, the City of Valdosta, and several Florida agencies have tested for bacterial contamination in the Withlacoochee River and its tributaries. This testing continues and focuses on measuring bacteria that are indicators of human or animal waste.

The Florida Department of Environmental Protection (FDEP) has also tested for chemical tracers (drugs and artificial sweeteners such as sucralose) and DNA markers of bacterial contamination (human, canine, ruminant, bird, seabird), and selected pesticides. From December through February, FDEP collected and analyzed 89 water samples, including some samples from the Suwannee River. Currently FDEP continues this work on a small subset of the sample collection locations on a monthly basis.

WWALS requested a copy of all results to date from FDEP and received them. WWALS has summarized the FDEP Findings in the following five tables.

  • Numbers of samples, locations, and the date range when samples were collected are shown in table 1.
  • Table 2 provides results for all samples and tests based on the frequency of detection, i.e. when measurements were above the method detection limit (MDL).
  • Tables 3, 4, and 5 show results for human and ruminant DNA biomarkers and the chemical marker, sucralose, by date, and sample location.

In the case of the human waste DNA marker, a total of 6 detections were reported. This represented approximately 7% of all samples. In all cases, measurements were near the reported limit of detection. On one sample date (1/22/20) a duplicate sample was collected and analyzed. In the duplicate the biomarker was not detected. Thus finding that the human waste biomarker was present remains uncertain. In summary there is some indication that human waste DNA was detected at selected locations on the Withlacoochee. But findings were sporadic and appear uncertain.

While detection of Human DNA biomarkers was infrequent, detection of Ruminant DNA markers at relatively high levels was common, especially in late December and early January. This supports the WWALS conclusion that continuing episodes of bacterial contamination in the Withlacoochee River starting at Knights Ferry Boat Ramp are most likely the result of cow manure washing off pastures within the Withlacoochee drainage basin, much of it coming down Okapilco Creek from Brooks and Colquitt Counties, Georgia. Stations with the highest levels of these biomarkers were at the GA state line (GA 31), and in Florida at CR 150 and FL 6. There were no discernable trends in levels of biomarkers detected suggesting that there are multiple sources of animal waste.

Chemical tracers that indicated the presence of sewage in samples was also common. The parameters sucralose, carbamazepine, and primidone were of particular note. The sweetener sucralose was detected in all samples. The most likely explanation of the presence of this compound in river samples is the discharge of treated wastewater into the river. This is for two reasons. The first is that human DNA biomarkers, an indicator of raw sewage were rarely detected. The second is that published studies that indicate that sucralose levels in wastewater are not reduced (except by dilution) when sewage passes through wastewater treatment facilities. The City of Valdosta’s Withlacoochee Wastewater Treatment Plant (WWTP) discharges into the Withlacoochee southwest of Valdosta.

Selected herbicides and insecticides were frequently detected, although in low concentrations. Potential for water quality impacts appear low.

Table 1. DNA bacterial biomarker and chemical sewage markers and pesticide tests conducted by the Florida Department of Environmental Protection (FDEP) following the Valdosta sewage spill on December 9. 2020.

Chemical sewage markers and pesticides tests
# samples date range
Withlacoochee River at GA 31 19 12/13/19 to 6/10/20
Withlacoochee River at CR 150 22 12/19/20 2/27/20
Withlacoochee River at FL 6 21 12/10/19 to 2/27/20
Withlacoochee River at CR 141 5 1/9/20 1/22/20
Suwanee River at US 90 18 12/10/19 to 2/27/20
Suwanee River at CR 250 3 1/9/20 to 2/27/20
Blank 1 1/22/2020
Duplicate 1 1/22/2020
DNA tests for bacteria source
# samples date range
Withlacoochee River at GA 31 19 12/16/19 to 6/10/20
Withlacoochee River at CR 150 22 12/10/19 to 6/10/20
Withlacoochee River at FL 6 22 12/10/19 to 6/10/20
Withlacoochee River at CR 141 5 1/9/20 to 1/22/20
Suwannee River at US 90 18 12/10/19 to 6/10/20
Suwannee River at CR 250 3 1/9/20 to 2/27/20
Blank 1 1/22/20
Duplicate 1 1/22/20

Table 2. Summary of the percentage of all FDEP samples with measurements above the reported limit of detection (MDL) of each analysis.

# samples # above method
detection limit
% samples with
DNA test to detect bacteria source
BacR-qPCR Ruminant DNA 79 32 41
DG3-qPCR Dog DNA 79 0 0
GFD-purified-qPCR Bird DNA 79 15 19
GULL2-qPCR Gull DNA 79 0 0
HF183-qPCR Human DNA 89 6 7
Chemical Sewage Markers
Acesulfame K artificial sweetener 89 2 2
Acetaminophen drug residue 89 2 2
Carbamazepine drug residue 89 65 73
Hydrocodone drug residue 89 6 7
Ibuprofen drug residue 89 2 2
Naproxen drug residue 89 2 2
Primidone drug residue 89 59 66
Sucralose artificial sweetener 89 89 100
2,4-D herbicide 89 57 64
Acetamiprid insecticide 89 12 13
Afidopyropen insecticide 89 0 0
AMPA herbicide breakdown product 89 34 38
Bentazon herbicide 89 88 99
Benzovindiflupyr fungicide 89 0 0
Clothianidin insecticide 89 13 15
Dinotefuran insecticide 89 88 99
Diuron herbicide 89 48 54
Endothall herbicide 89 0 0
Fenuron herbicide 89 1 1
Fluridone herbicide 89 15 17
Glufosinate herbicide 89 0 0
Glyphosate herbicide 89 9 10
Imazapyr herbicide 89 88 99
Imidacloprid insecticide 89 86 97
Linuron herbicide 89 0 0
Mandestrobin fungicide 89 0 0
MCPP herbicide 89 57 64
Pyraclostrobin fungicide 89 0 0
Thiamethoxam insecticide 89 48 54
Tolfenpyrad insecticide 89 0 0
Triclopyr herbicide 89 1 1

Table 3. FDEP Human DNA Biomarker test results
for selected Withlacoochee and Suwannee River sample collection locations
(units are GEU/100 mL)

Withlacoochee River Suwannee River
GA 31 CR 150 FL 6 US 90 CR 250
10-Dec-19 <MDL <MDL
11-Dec-19 <MDL <MDL
13-Dec-19 <MDL <MDL
16-Dec-19 <MDL <MDL <MDL <MDL
20-Dec-19 <MDL <MDL <MDL <MDL
26-Dec-19 <MDL <MDL <MDL <MDL
27-Dec-19 <MDL <MDL <MDL <MDL
2-Jan-20 <MDL <MDL <MDL <MDL
6-Jan-20 <MDL <MDL <MDL <MDL
7-Jan-20 <MDL <MDL <MDL <MDL
8-Jan-20 <MDL <MDL <MDL <MDL
9-Jan-20 <MDL <MDL <MDL <MDL <MDL
13-Jan-20 <MDL <MDL <MDL
14-Jan-20 <MDL <MDL <MDL
15-Jan-20 <MDL <MDL <MDL
16-Jan-20 <MDL <MDL <MDL <MDL
21-Jan-20 <MDL <MDL <MDL <MDL
22-Jan-20 <MDL 170 <MDL <MDL
23-Jan-20 <MDL <MDL <MDL <MDL
25-Feb-20 <MDL 370 320 <MDL <MDL
27-Feb-20 550 360 470 <MDL <MDL
10-Jun-20 <MDL <MDL <MDL <MDL

Table 4. FDEP Ruminant DNA Biomarker test results
for selected Withlacoochee and Suwannee River sample collection locations
(units are TSC/100 mL)

Withlacoochee River Suwannee River
GA 31 CR 150 FL 6 US 90 CR 250
16-Dec-19 <MDL <MDL <MDL <MDL
20-Dec-19 <MDL <MDL <MDL <MDL
26-Dec-19 235000 30600 <MDL 2200
27-Dec-19 12000 24400 <MDL <MDL
2-Jan-20 <MDL <MDL <MDL <MDL
6-Jan-20 351000 <MDL <MDL <MDL
7-Jan-20 108000 636000 2300 3800
8-Jan-20 19000 31100 228000 <MDL
9-Jan-20 <MDL 5500 3100 4400 <MDL
13-Jan-20 3700 2100 <MDL
14-Jan-20 45300 136000 <MDL
15-Jan-20 1800 20700 19300
16-Jan-20 1800 <MDL 2000 <MDL
21-Jan-20 4000 <MDL <MDL <MDL
22-Jan-20 <MDL <MDL <MDL <MDL
23-Jan-20 <MDL <MDL <MDL <MDL
25-Feb-20 <MDL <MDL <MDL <MDL <MDL
27-Feb-20 37600 18100 21400 11000 99900
10-Jun-20 <MDL <MDL <MDL <MDL

Table 5. FDEP chemical sewage marker test results
for the artificial sweetener sucralose

(Units are ug L-1)

Withlacoochee River Suwannee River
GA 31 CR 150 FL 6 HWY90 CR 250
10-Dec-19 1.6 1.3 0.27
11-Dec-19 1.9 1.1 0.3
13-Dec-19 1.4 1.5 1.2 0.25
16-Dec-19 1.8 1 1.7 0.24
20-Dec-19 4.3 1.6 1 0.26
26-Dec-19 4.5 8.4 4.4 0.23
27-Dec-19 2.5 4.4 6.7 0.28
2-Jan-20 1.1 0.9 1.1 0.8
6-Jan-20 0.81 0.8 0.75 0.33
7-Jan-20 1.1 0.89 0.81 0.23
8-Jan-20 1.1 0.94 0.84 0.21
9-Jan-20 1.1 1.3 0.9 0.2 0.23
13-Jan-20 0.7 0.75 0.63

14-Jan-20 0.68 0.59 0.67

15-Jan-20 0.67 0.62 0.57

16-Jan-20 0.62 0.72 0.63 0.17
21-Jan-20 0.5 0.57 0.55 0.16
22-Jan-20 0.46 0.56 0.48 0.2
23-Jan-20 0.58 0.79 0.57 0.18
25-Feb-20 0.33 0.35 0.33 0.092 0.16
27-Feb-20 0.31 0.29 0.3 0.092 0.15

Editor’s note: to deal with the variant names found in the source spreadsheets, I normalized the roads to GA 31 (near State Line Boat Ramp), CR 150 (near Sullivan Launch), FL 6 (near Madison Blue Spring State Park), CR 141 (near Allen Ramp), US 90 (just below Suwannee River State Park and the Withlacoochee River Confluence with the Suwannee River), and CR 250 (near Dowling Park Ramp). Also, I normalized FL 145 and CR 145 to GA 31, because at Horn Bridge across the Withlacoochee River just north of the GA-FL line, the road is in Georgia and is actually GA 31 or Madison Highway (near State Line Boat Ramp). Dr. Potter’s tables are based on these normalizations, which also correspond to those used in the WWALS Composite Spreadsheet of Georgia and Florida bacterial water quality results and rainfall.


Thanks to Merillee Malwitz-Jipson for helping persuade FDEP to collect and analyze this data (see Credit Where Credit Is Due. Thanks to Kristin Cathey for facilitating an appropriate path to FDEP to get the data. And thanks again to Katrina Yancey of FDEP for sending the data. Finally, thanks to WWALS Science Committee Chair Dr. Thomas Potter for the analysis.

 -jsq, John S. Quarterman, Suwannee RIVERKEEPER®

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