Page 1 of 39

Syngenta is providing responses to questions from EPA in the e-mail titled “Triazines: Questions 

on CWSs” of February 27, 2009. These questions relate to Syngenta’s request for waiver of 80 

CWS from participation in the Atrazine Monitoring Program (AMP). These 80 CWS were 

submitted previously for waiver since they have met the monitoring requirements as set forth 

in the Memorandum of Agreement (MOA). 

EPA Question Concerning CWS Requiring Privately Contracted Monitoring Firms – “Can you 

provide a list of all the CWSs that are refusing to monitor in 2009, and for which you would 

need to hire a company to monitor the system? “ 

Syngenta Response Of the 80 CWS included in our current waiver requests, 11 systems 

currently require third party sampling for compliance with the monitoring program. These are: 

Hillsboro IL (IL1350300) 

Bedford IN (IN5247001) 

Winslow IN (IN5263006) 

Beloit KS (KS2012301) 

Burlington KS (KS2003101) 

Carbondale KS (KS2013914) 

Maryville MO (MO1010508) 

McClure OH (OH3500711) 

Mt. Orab OH (OH0801011) 

Upper Sandusky OH (OH8800511) 

Waynoka OH (OH8800511) 

The Linn Valley Lakes POA (KS2010712) has is also becoming more difficult and may need to go 

to a third party sampler, though this CWS and all connections are within a fully gated 

community into which we are unable to send a third party to collect samples. 

Questions on CWS in the AMP – The following are responses to the questions in the 

spreadsheet enclosed in EPA’s e-mail of February 27, 2009 (M. Biscoe to D. Campbell, subject: 

“Triazines: Questions on CWSs”). We are initially addressing only the CWS which have met the 

waiver criteria of the Memorandum of Agreement; additional information on the other CWS 

will be provided separately. 
Page 2 of 39

Analytical Methodology and Data Interpolation - The questions posed by the EPA are centered 

on concentrations of total chlorotriazines (TCT) in finished drinking water and changes in these 

levels in certain community water systems over specific timeframes. 

The analytical methodology used in the AMP was updated as the program progressed. In 2003 

(and even earlier in pre-AMP monitoring programs), a technique known as immunoassay (IA) 

was used to screen for atrazine residues. If a result from IA was greater than or equal to 3 ppb, 

the sample was specifically quantified using Gas Chromatography / Mass Spectrometry 

(GC/MS), which analyzed for parent atrazine, simazine, and the 3 chlorinated degradates. 

When some samples with IA results slightly greater than 3 ppb were reanalyzed by the directmeasurement GC/MS technique, they will at times show atrazine (and summed TCT) levels 

below 3 ppb. 

Starting in August 2005 (and earlier in certain CWS), the IA and the GC/MS methodology was 

replaced with a new analytical method that used direct injection of water samples into Liquid 

Chromatography / Quadruple Mass Spectometry (LC/MS). This method allowed for direct 

measurement of all analytes that comprise TCT in a rapid, direct injection method and 

eliminated the need to screen for residues with the IA method. 

For EPA’s calculation of the finished water TCT 90-day rolling averages, it is our understanding 

that EPA used only data for which atrazine, simazine and the chlorodegradates were specifically 

measured by either GC/MS or LC/MS, and did not use the IA screen results. To fill in data gaps 

between GC/MS or LC/MS measured values, the EPA used linear interpolation to generate 

interim 90-day rolling average values. As previously mentioned, prior to August 2005 and the 

routine analysis of all samples by LC/MS, there were relatively few data points analyzed by 

GC/MS, as only those that were higher than 3 ppb by IA were reanalyzed. In the AMP, the large 

majority of atrazine sample concentrations have been less than 3.0 ppb. As a result, sole use of 

GC/MS data in the early years leads to a partial data set that over-estimates 90-day rolling 

average values, in many cases to a large degree, as illustrated below. 

In the Atrazine Memorandum of Agreement, EPA provided equations for the estimation of TCT 

from parent atrazine data. Using these equations to generate a full set of TCT concentrations 

from all available IA data (plus all available GC/MS data) prior to August 2005 resulted in much 

lower 90-day rolling averages in most cases when compared to calculation using the partial 

data set selected by EPA. While we acknowledge that EPA will not be using the IA TCT result in 

the cumulative risk assessment, we provide this analysis to answer the specific questions 

concerning perceived decreases in TCT in certain CWS in AMP. Provided below are graphs and 

data summaries that compare both the full data set (defined here as TCT derived from IA, 

GC/MS, and LC/MS) to the partial data set (defined as TCT from GC/MS and LC/MS with linear 

interpolation as selected by EPA) to illustrate the effect of the use of the GC/MS for the higher 
Page 3 of 39

residue samples. As these graphs and tables show, in many cases the TCT fluctuations and 

trends that are in question, are primarily a function of the rolling averages derived from a 

partial data set during the period from 2003-05. Each CWS that has met the criteria for waiver 

in the Memorandum of Agreement is specifically addressed below. 
Page 4 of 39

EPA Question 1: “What caused the substantial drop in TCT levels between the following 

years?”

Westport, IN, 2003-05 

Syngenta Response: The program monitoring data available for Westport IN, listed by 

analytical methodology used, are summarized in Table 1. In 2003, only 3 samples in 2003 had 

atrazine residues greater than 3.0 ppb by IA which were re-analyzed using the GC/MS method. 

In 2004, no samples had residues greater than 3.0 ppb, and therefore none of the samples were 

analyzed by GC/MS. In 2005, 1 sample was confirmed by GC/MS and 19 were analyzed using 

the LC/MS method. As Figure 1 shows, use of the partial data set selected by EPA (as we 

understand it) prior to August 2005 resulted in an over-estimation of 90-day rolling TCT levels. 

Using only the GC/MS analytical TCT data resulted in a maximum 90-day TCT average value of 

16.7 ppb in 2003 (see green trace in Figure 1). However, when the full data set (i.e. inclusion of 

TCT calculated from IA results) is used to calculate 90-day rolling averages, the maximum 90-

day TCT in 2003 is 2.55 ppb (trace with black diamonds). As can be seen in Figure 1, the 90-day 

rolling averages have remained low (below 5 ppb using the full data set) over the six year 

period. In Figure 2 the individual TCT sample results have been plotted. Individual atrazine and 

TCT concentrations have consistently remained below 5 ppb (and most near method detection 

limits) with the exception of a single sample occurrence in 2003 (corresponding to an atrazine 

detection of 18.52 ppb on May 6, 2003) and 2 sample occurrences in 2007 (corresponding to 

simazine detections of 19.24 and 15.69 ppb on June 4, 2007 and June 11, 2007, respectively). 

Year Total Samples (n)

IA GC/MS LC/MS

2003 24 21 3 0

2004 31 31 0 0

2005 32 12 1 19

2006 32 0 0 32

2007 34 0 0 34

2008 32 0 0 32

Method

Table 1 

Samples Analyzed by Immuno-assay, GC/MS or LCMS from the AMP at the 

Westport, IN CWS from 2003-2008 
Page 5 of 39

0

5

10

15

20

25

30

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

90-day TCT Rolling Average (ppb)

Figure 1

90-day TCT Rolling Averages in Finished Water Comparing Use of All Triazine Analytical 

Data to MS Method Only Data (With Interpolation), Westport, IN CWS 2003-2008

90-day TCT

(Full Data Set: IA, GC/MS, LC/MS Sample Results)

90-day TCT

(GC/MS and LC/MS Sample Results)

90-day TCT

(Partial Data Set: GC/MS and LC/MS with Linear Interpolation)

0

5

10

15

20

25

30

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Concentration (ppb)

Figure 2

Individual Sample Atrazine Plus Metabolites, Simazine, and Atrazine Plus Metabolites 

Plus Simazine (TCT) in Finished Water at Westport, IN CWS from 2003-2008

Atz + Metab

(IA, GC/MS, LC/MS)

Simazine

(GC/MS, LC/MS) 

Atz+Metab+Sim

(GC/MS, LC/MS)
Page 6 of 39

Carlinville, IL, 2004 – 2005 

Syngenta Response: The program monitoring data available for Carlinville, IL, listed by 

analytical methodology used, are summarized in Table 2. Eleven of 25 analyses in 2003 and 6 of 

29 analyses in 2004 were greater than 3.0 ppb by IA and re-analyzed by GC/MS. In 2005, 21 of 

34 analyses were by LC/MS. When using the partial data set selected by EPA, with 

extrapolation between GC/MS values, to calculate 90-day rolling averages, there is a significant 

overestimation in finished water 90-day TCT averages in 2003 and 2004 (Figure 3, green trace). 

Using the full data set, 90-day TCT levels remained steady and consistently below 4 ppb in 2003 

and 2004 and below 2 ppb from 2005 to 2008 (Figure 3, black and orange traces). Individual 

sample results, by analytical methodology, are shown in Figure 4. Individual residue values are 

generally low (rarely above 4 ppb). 

Year Total Samples (n)

IA GC/MS LC/MS

2003 25 14 11 0

2004 29 23 6 0

2005 34 13 0 21

2006 31 0 0 31

2007 33 0 0 33

2008 30 0 0 30

Table 2

 Samples Analyzed by Immuno-assay, GC/MS or LCMS from the 

VMP and AMP at the Carlinville, IL CWS from 2003-2008 

Method
Page 7 of 39

0

2

4

6

8

10

12

14

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Concentration (ppb)

Figure 3

90-day TCT Rolling Averages in Finished Water Comparing Use of All Triazine Analytical 

Data to MS Method Only Data (With Interpolation), Carlinville, IL CWS 2003-2008

90-day TCT

(Full Data Set: IA, GC/MS, LC/MS Sample Results)

90-day TCT

(GC/MS and LC/MS Sample Results)

90-day TCT

(Partial Data Set: GC/MS and LC/MS with Linear Interpolation)

0

2

4

6

8

10

12

14

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Concentration (ppb)

Figure 4

Atrazine Plus Metabolites, Simazine, and Atrazine Plus Metabolites Plus Simazine in 

Finished Water at Carlinville, IL 2003-2008

Atz + Metab

(IA, GC/MS, LC/MS)

Simazine

(GC/MS, LC/MS) 

Atz+Metab+Sim

(GC/MS, LC/MS)

Concordia, MO, 2004 – 2005 

Syngenta Response: The program monitoring data available for Concordia, MO, listed by 

analytical methodology used, are summarized in Table 3. Five of 24 analyses in 2003 and 7 of 

31 analyses in 2004 were greater than 3.0 ppb by IA and confirmed by GC/MS. LC/MS 

methodology was used on 13 of 32 analyses in 2005. Using the partial data set selected by EPA 
Page 8 of 39

show a slight over-estimation of 90-day TCT averages in 2003 though the results are generally 

very similar to the full data set results (Figure 5). Over the six year monitoring period (2003-

2008), the yearly maximum 90-day TCT averages varied between 1 and 4 ppb (Figure 5). 

Individual data are also plotted and labeled as to analytical methodology (Figure 6). 

Year Total Samples (n)

IA GC/MS LC/MS

2003 24 19 5 0

2004 31 24 7 0

2005 32 19 0 13

2006 28 0 0 28

2007 24 0 0 24

2008 23 0 0 23

Table 3

 Samples Analyzed by Immuno-assay, GC/MS or LCMS from the VMP 

and AMP at the Concordia, MO CWS from 2003-2008

Method

0

1

2

3

4

5

6

7

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Concentration (ppb)

Figure 5

90-day TCT Rolling Averages in Finished Water Comparing Use of All Triazine Analytical 

Data to MS Method Only Data (With Interpolation), Concordia, MO CWS 2003-2008

90-day TCT

(Full Data Set: IA, GC/MS, LC/MS Sample Results)

90-day TCT

(GC/MS and LC/MS Sample Results)

90-day TCT

(Partial Data Set: GC/MS and LC/MS with Linear Interpolation)
Page 9 of 39

0

1

2

3

4

5

6

7

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Concentration (ppb)

Figure 6

Atrazine Plus Metabolites, Simazine, and Atrazine Plus Metabolites Plus Simazine in 

Finished Water at Concordia, MO 2003-2008 

Atz + Metab

(IA, GC/MS, LC/MS)

Simazine

(GC/MS, LC/MS) 

Atz+Metab+Sim

(GC/MS, LC/MS)

Waynoka Regional Water, OH, 2004 – 2005 

Syngenta Response: There were no samples where parent atrazine was greater than 3.0 ppb, 

and therefore no GC/MS analyses were performed in 2003. In 2004, 10 of 21 analyses were 

confirmed by GC/MS. In 2005, 6 samples were confirmed by GC/MS, 15 samples were analyzed 

using the LC/MS method and 15 were analyzed using IA methodology (Table 4). As shown in 

Figure 7, the generally higher portion of GC/MS data resulted in nearly identical 2004 and 2005 

traces using either the partial data set selected by EPA or the full data set (including TCT 

calculated from IA results). Individual finished water sample results from 2004 to 2008 are 

provided in Figure 8. 

The Waynoka CWS uses a backup lake to fill their primary reservoir early in the year while 

surface runoff accounts for the water in the reservoir later in the year. The backup lake uses 

water from a small stream called Sycamore Run. As this is a reservoir system, the water turnover is relatively slow compared to a typical stream system, and the residues occurring in 2004 

were slowly dissipated. Individual residue results in Figure 8 show that other than the single 

peak in 2004 and early 2005, no value has risen above 3 ppb across the 6 year period. 
Page 10 of 39

Year Total Samples (n)

IA GC/MS LC/MS

2003 13 13 0 0

2004 21 11 10 0

2005 36 15 6 15

2006 35 0 0 35

2007 35 0 0 35

2008 35 0 0 35

Table 4

 Samples Analyzed by Immuno-assay, GC/MS or LCMS from the 

AMP at the Waynoka, OH CWS from 2003-2008

Method

0

2

4

6

8

10

12

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Concentration (ppb)

Figure 7

90-day TCT Rolling Averages in Finished Water Comparing Use of All Triazine Analytical 

Data to MS Method Only Data (With Interpolation), 

Waynoka Reg Water, OH 2003-2008

90-day TCT

(Full Data Set: IA, GC/MS, LC/MS Sample Results)

90-day TCT

(GC/MS and LC/MS Sample Results)

90-day TCT

(Partial Data Set: GC/MS and LC/MS with Linear Interpolation)
Page 11 of 39

0

2

4

6

8

10

12

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Concentration (ppb)

Figure 8

Atrazine Plus Metabolites, Simazine, and Atrazine Plus Metabolites Plus Simazine in 

Finished Water at Waynoka Reg Water, OH 2003-2008

Atz + Metab

(IA, GC/MS, LC/MS)

Simazine

(GC/MS, LC/MS) 

Atz+Metab+Sim

(GC/MS, LC/MS)

Osawatomie, KS, 2004 – 2006 

Syngenta Response: The program monitoring data available for Osawatomie, KS, listed by 

analytical methodology used, are summarized in Table 6. Six of 20 analyses in 2003 and 3 of 

33 analyses in 2004 were above 3.0 ppb using IA and were re-analyzed by GC/MS methodology. 

In 2005, 3 samples were analyzed by GC/MS, 14 were analyzed using LC/MS methodology and 

18 by IA methodology. Using the partial data set selected by EPA, the 90-day rolling averages 

are overestimated to a large degree in 2004 when compared to the full data set, including TCT 

calculated from IA data. Results from the full data set indicate that 90-day TCT concentrations 

have remained low and relatively constant over the six year period (2003-2008). Maximum 90-

day average TCT concentrations for this CWS have typically oscillated between 1 and 4 ppb, on 

an annual basis. Individual samples also reflect this well established seasonal pattern from corn 

herbicide use (Figure 10). 
Page 12 of 39

Year Total Samples (n)

IA GC/MS LC/MS

2003 20 14 6 0

2004 33 30 3 0

2005 35 18 3 14

2006 34 0 0 34

2007 34 0 0 34

2008 34 0 0 34

Table 5

 Samples Analyzed by Immuno-assay, GC/MS or LCMS from the 

AMP at the Osawatomie, KS CWS from 2003-2008

Method

0

2

4

6

8

10

12

14

16

18

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Concentration (ppb)

Figure 9

90-day TCT Rolling Averages in Finished Water Comparing Use of All Triazine Analytical 

Data to MS Method Only Data (With Interpolation), Osawatomie, KS CWS 2003-2008

90-day TCT

(Full Data Set: IA, GC/MS, LC/MS Sample Results)

90-day TCT

(GC/MS and LC/MS Sample Results)

90-day TCT

(Partial Data Set: GC/MS and LC/MS with Linear Interpolation)
Page 13 of 39

0

2

4

6

8

10

12

14

16

18

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Concentration (ppb)

Figure 10

Atrazine Plus Metabolites, Simazine, and Atrazine Plus Metabolites Plus Simazine in 

Finished Water at Osawatomie, KS CWS 2003-2008

Atz + Metab

(IA, GC/MS, LC/MS)

Simazine

(GC/MS, LC/MS) 

Atz+Metab+Sim

(GC/MS, LC/MS)

Iberville Water District #3, LA, 2004 – 2006 

Syngenta Response: The program monitoring data available for Iberville, LA, listed by analytical 

methodology used, are summarized in Table 6. Nine of 39 samples in 2003 and 9 of 46 analyses 

in 2004 were confirmed by GC/MS. In 2005, eight samples were confirmed by GC/MS, 21 were 

analyzed following LC/MS methods and 14 by IA. 

Using the partial data set selected by EPA, the 90-day rolling averages are overestimated to a 

large degree in 2003 and 2004 when compared to the full data set. Results from the full data 

set indicate that 90-day TCT concentrations have remained low and relatively constant over the 

six year period (2003-2008). TCT concentrations oscillate annually between 0.5 ppb and 4 ppb 

following a seasonal herbicide use pattern for this stream-based CWS. Individual samples 

confirm the oscillating seasonal pattern which follows periods of herbicide use (Figure 12). 

Figure 12 also demonstrates that the seasonal spikes of atrazine have trended lower since 

2005. This timeframe also corresponds to a period of regular watershed atrazine label 

education and mitigation meetings in the Iberville area. 
Page 14 of 39

Year Total Samples (n)

IA GC/MS LC/MS

2003 39 30 9 0

2004 46 37 9 0

2005 43 14 8 21

2006 46 0 0 46

2007 46 0 0 46

2008 44 0 0 44

Table 6

 Samples Analyzed by Immuno-assay, GC/MS or LCMS from the VMP 

and AMP at the Iberville, LA CWS from 2003-2008

Method

0

2

4

6

8

10

12

14

16

18

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Concentration (ppb)

Figure 11

90-day TCT Rolling Averages in Finished Water Comparing Use of All Triazine Analytical 

Data to MS Method Only Data (With Interpolation), Iberville, LA CWS 2003-2008

90-day TCT

(Full Data Set: IA, GC/MS, LC/MS Sample Results)

90-day TCT

(GC/MS and LC/MS Sample Results)

90-day TCT

(Partial Data Set: GC/MS and LC/MS with Linear Interpolation)
Page 15 of 39

0

2

4

6

8

10

12

14

16

18

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Concentration (ppb)

Figure 12

Atrazine Plus Metabolites, Simazine, and Atrazine Plus Metabolites Plus Simazine in 

Finished Water at Iberville, LA 2003-2008

Atz + Metab

(IA, GC/MS, LC/MS)

Simazine

(GC/MS, LC/MS) 

Atz+Metab+Sim

(GC/MS, LC/MS)

 Aqua Illinois CWS, 2005 – 2006 

Syngenta Response: Available samples for Aqua IL are listed by analytical methodology in Table 

7. Seven of 27 samples in 2003 and 4 of 33 analyses in 2004 were confirmed using GC/MS 

methodology. In 2005, 5 samples were by GC/MS (confirmation of IA results), 15 by LC/MS and 

15 by IA methodology. Using the partial data set selected by EPA, the 90-day rolling averages 

are overestimated between 2003 through the first part of 2005 when compared to the full data 

set (Figure 13). Results from the full data set indicate that 90-day TCT concentrations have 

remained low and relatively constant over the six year period (2003-2008). Individual samples 

confirm the oscillating seasonal pattern which follows periods of herbicide use (Figure 14). 
Page 16 of 39

Year Total Samples (n)

IA GC/MS LC/MS

2003 27 20 7 0

2004 33 29 4 0

2005 35 15 5 15

2006 34 0 0 34

2007 34 0 0 34

2008 35 0 0 35

Table 7

 Samples Analyzed by Immuno-assay, GC/MS or LCMS from the VMP and AMP 

at the Aqua IL WD, Vermillion Co., IL CWS from 2003-2008

Method

0

2

4

6

8

10

12

14

16

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Concentration (ppb)

Figure 13

90-day TCT Rolling Averages in Finished Water Comparing Use of All Triazine Analytical 

Data to MS Method Only Data (With Interpolation), Aqua IL, Vermillion Co., IL CWS 

2003-2008

90-day TCT

(Full Data Set: IA, GC/MS, LC/MS Sample Results)

90-day TCT

(GC/MS and LC/MS Sample Results)

90-day TCT

(Partial Data Set: GC/MS and LC/MS with Linear Interpolation)
Page 17 of 39

0

2

4

6

8

10

12

14

16

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Concentration (ppb)

Figure 14

Atrazine Plus Metabolites, Simazine, and Atrazine Plus Metabolites Plus Simazine in 

Finished Water at Aqua IL, Vermillion Co, IL 2003-2008

Atz + Metab

(IA, GC/MS, LC/MS)

Simazine

(GC/MS, LC/MS) 

Atz+Metab+Sim

(GC/MS, LC/MS)

Versailles, IN, 2005 – 2006 

Syngenta Response: Available monitoring data for Versailles IN are listed by analytical 

methodology used, in Table 8. Twelve of 24 analyses in 2003 and 23 of 31 analyses in 2004 

were confirmed using the GC/MS method. In 2005, 22 were by GC/MS (IA confirmation) and 13 

by LC/MS. Since there were a relatively high percentage of GC/MS method analyses during this 

time, the use of the partial and full data sets to calculate finished water 90-day TCT 

concentrations are nearly identical (Figure 15). 90-day TCT concentrations in finished water 

have remained consistently below 2 ppb from mid-2005 to December 2008. Individual samples 

indicate a reduction in TCT concentrations after the 2005 use season (Figure 16). 

A phone conversation (3/16/09) with the Versailles water plant operator revealed that they 

began using powdered activated carbon (PAC) approximately 3-4 years ago. This change in 

treatment process corresponds to the drop in TCT levels observed in finished water beginning 

mid to late 2005 (Figure 15). The water source for Versailles is an approximately 300 acre 

reservoir. The water plant operator indicated that sedimentation of the lake is one of their 

primary concerns. Sedimentation of the reservoir will lead to generally poorer water quality 

and increased levels of eutrophication. These processes raise the levels of natural organic 

matter creating taste and odor problems as well as increased levels of disinfection byproducts. 

One common treatment process to reduce the disinfection byproduct levels is the use of 

powdered activated carbon. 
Page 18 of 39

Year Total Samples (n)

IA GC/MS LC/MS

2003 24 12 12 0

2004 31 8 23 0

2005 35 0 22 13

2006 29 0 0 29

2007 33 0 0 33

2008 31 0 0 31

Table 8

 Samples Analyzed by Immuno-assay, GC/MS or LCMS from the AMP 

at the Versailles, IN CWS from 2003-2008

Method

0

2

4

6

8

10

12

14

16

18

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Concentration (ppb)

Figure 15

90-day TCT Rolling Averages in Finished Water Comparing Use of All Triazine Analytical 

Data to MS Method Only Data (With Interpolation), Versailles, IN CWS 2003-2008

90-day TCT

(Full Data Set: IA, GC/MS, LC/MS Sample Results)

90-day TCT

(GC/MS and LC/MS Sample Results)

90-day TCT

(Partial Data Set: GC/MS and LC/MS with Linear Interpolation)
Page 19 of 39

0

5

10

15

20

25

30

35

40

45

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Concentration (ppb)

Figure 16

Atrazine Plus Metabolites, Simazine, and Atrazine Plus Metabolites Plus Simazine in 

Finished Water at Versailles, IN 2003-2008

Atz + Metab

(IA, GC/MS, LC/MS)

Simazine

(GC/MS, LC/MS) 

Atz+Metab+Sim

(GC/MS, LC/MS)

Osage County RWD #3, KS, 2005 – 2006 

Syngenta Response: Available monitoring data for Osage County, KS, are listed by analytical 

methodology used in Table 9. Five of 26 analyses in 2003 and none of the 33 analyses in 2004 

were confirmed using GC/MS methodology. In 2005, 2 samples were analyzed by GC/MS, 10 by 

LC/MS and 23 by IA. In Figure 17, 90-day TCT rolling averages are graphed using the partial 

data set selected by EPA, and the full data set with the regression equations used to generate 

TCT values for IA data. These graphs show that 90-day TCT levels have remained low over the 

six year period (2003-2008). TCT concentrations tend to oscillate annually between 1 ppb and 4 

ppb following a seasonal herbicide use pattern. Individual samples also demonstrate the 

oscillating seasonal pattern which follows periods of herbicide use (Figure 18). 
Page 20 of 39

Year Total Samples (n)

IA GC/MS LC/MS

2003 26 21 5 0

2004 33 33 0 0

2005 35 20 2 13

2006 33 0 0 33

2007 34 0 0 34

2008 30 0 0 30

Table 9

 Samples Analyzed by Immuno-assay, GC/MS or LCMS from the AMP 

at the Osage Co, KS CWS from 2003-2008

Method

0

2

4

6

8

10

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Concentration (ppb)

Figure 17

90-day TCT Rolling Averages in Finished Water Comparing Use of All Triazine Analytical 

Data to MS Method Only Data (With Interpolation), Osage Co RWD #3, KS CWS 2003-

2008

90-day TCT

(Full Data Set: IA, GC/MS, LC/MS Sample Results)

90-day TCT

(GC/MS and LC/MS Sample Results)

90-day TCT

(Partial Data Set: GC/MS and LC/MS with Linear Interpolation)
Page 21 of 39

0

1

2

3

4

5

6

7

8

9

10

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Concentration (ppb)

Figure 18

Atrazine Plus Metabolites, Simazine, and Atrazine Plus Metabolites Plus Simazine in 

Finished Water at Osage Co RWD #3, KS 2003-2008

Atz + Metab

(IA, GC/MS, LC/MS)

Simazine

(GC/MS, LC/MS) 

Atz+Metab+Sim

(GC/MS, LC/MS)

Webster Co Water District, KY, 2005 – 2006 

Syngenta Response: Available monitoring data for Webster Co, KY, are listed by analytical 

methodology used in Table 10. Seven of 27 analyses in 2003 and 3 of 33 analyses in 2004 were 

confirmed using GC/MS methodology. In 2005, 1 sample was analyzed by the GC/MS method, 

14 by the LC/MS method and 21 by IA. Using the partial data set selected by EPA, the 90-day 

rolling averages are overestimated between 2003 through the first part of 2005 when 

compared to the full data set (Figure 19). Results from the full data set indicate that 90-day TCT 

concentrations have remained low and relatively constant over the six year period (2003-2008). 

Individual samples confirm the oscillating seasonal pattern which follows periods of herbicide 

use (Figure 20). 

A phone conversation (3/20/09) with the water plant operator revealed that they began using 

powdered activated carbon (PAC) 3-4 years ago, to better control disinfection byproducts. The 

raw water source for Webster County WD has remained the Green River throughout the 

monitoring period (wells were used prior to 1999). Ninety-day TCT concentrations in finished 

water have remained consistently below about 1 ppb from mid-2005 through December 2008. 
Page 22 of 39

Year Total Samples (n)

IA GC/MS LC/MS

2003 27 20 7 0

2004 33 30 3 0

2005 36 21 1 14

2006 35 0 0 35

2007 35 0 0 35

2008 33 0 0 33

Table 10

 Samples Analyzed by Immuno-assay, GC/MS or LCMS from the AMP 

at the Webster Co WD, KY CWS from 2003-2008

Method

0

1

2

3

4

5

6

7

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Concentration (ppb)

Figure 19

90-day TCT Rolling Averages in Finished Water Comparing Use of All Triazine Analytical 

Data to MS Method Only Data (With Interpolation), Webster Co WD, KY CWS 2003-2008

90-day TCT

(Full Data Set: IA, GC/MS, LC/MS Sample Results)

90-day TCT

(GC/MS and LC/MS Sample Results)

90-day TCT

(Partial Data Set: GC/MS and LC/MS with Linear Interpolation)
Page 23 of 39

0

1

2

3

4

5

6

7

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Concentration (ppb)

Figure 20

Atrazine Plus Metabolites, Simazine, and Atrazine Plus Metabolites Plus Simazine in 

Finished Water at Webster Co WD, KY CWS 2003-2008

Atz + Metab

(IA, GC/MS, LC/MS)

Simazine

(GC/MS, LC/MS) 

Atz+Metab+Sim

(GC/MS, LC/MS)

Piqua, OH, 2005 – 2006 

Syngenta Response: Available monitoring data for Piqua, OH are listed by analytical 

methodology used in Table 11. Five of 20 analyses in 2003 and 10 of 33 analyses in 2004 were 

confirmed using GC/MS methodology. In 2005, 8 samples were analyzed (confirmed) using the 

GC/MS method, 17 by the LC/MS method and 9 by IA. Using the partial data set selected by 

EPA, the 90-day rolling averages are overestimated between 2003 through the first part of 

2005, especially in 2004, when compared to the full data set (Figure 21). Results from the full 

data set indicate that 90-day TCT concentrations have remained low and relatively constant 

over the six year period (2003-2008). Individual samples confirm that the results have generally 

been low with only relatively two short-lived peaks in concentrations in the six year monitoring 

period (Figure 22). 
Page 24 of 39

Year Total Samples (n)

IA GC/MS LC/MS

2003 20 15 5 0

2004 33 23 10 0

2005 34 9 8 17

2006 34 0 0 34

2007 35 0 0 35

2008 35 0 0 35

Table 11

 Samples Analyzed by Immuno-assay, GC/MS or LCMS from the AMP 

at the Piqua, OH CWS from 2003-2008

Method

0

10

20

30

40

50

60

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Concentration (ppb)

Figure 21

90-day TCT Rolling Averages in Finished Water Comparing Use of All Triazine Analytical 

Data to MS Method Only Data (With Interpolation), Piqua, OH CWS 2003-2008

90-day TCT

(Full Data Set: IA, GC/MS, LC/MS Sample Results)

90-day TCT

(GC/MS and LC/MS Sample Results)

90-day TCT

(Partial Data Set: GC/MS and LC/MS with Linear Interpolation)
Page 25 of 39

0

10

20

30

40

50

60

70

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Concentration (ppb)

Figure 22

Atrazine Plus Metabolites, Simazine, and Atrazine Plus Metabolites Plus Simazine in 

Finished Water at Piqua, OH 2003-2008

Atz + Metab

(IA, GC/MS, LC/MS)

Simazine

(GC/MS, LC/MS) 

Atz+Metab+Sim

(GC/MS, LC/MS)

Centralia, IL (discussed during teleconference) 

Syngenta Response: Available monitoring data for Centralia IL are listed by analytical 

methodology used in Table 12. Eleven of 30 analyses in 2003 and 10 of 33 analyses in 2004 

were confirmed using GC/MS methodology. In 2005, 12 samples were analyzed by GC/MS and 

20 samples were analyzed LC/MS method. The monitoring results for Centralia are graphically 

depicted (Figures 25 and 26, below) in the discussion for Question 2, below. Due to the 

relatively high number of samples analyzed by GC/MS in 2003 and 2004, the 90-day rolling 

averages are similar when calculated using either the partial data set selected by EPA, or the 

full data set including TCT calculated from IA. Maximum 90-day TCT rolling averages are shown 

in Figure 25 while the individual analyses are shown in Figure 26. 

A conversation with Centralia CWS plant personnel (3/21/09) suggest that one correlation may 

be that a, while Raccoon Lake used to be the primary raw water source, around the time 

January 2008, the raw water source was switched to Carlyle Lake. The reason given is that this 

source requires less water treatment chemical input. Carlyle Lake is expected to remain as the 

primary raw water source for the foreseeable future. 
Page 26 of 39

Year Total Samples (n)

IA GC/MS LC/MS

2003 30 19 11 0

2004 33 23 10 0

2005 35 3 12 20

2006 34 0 0 34

2007 34 0 0 34

2008 35 0 0 35

Table 12

Samples Analyzed by Immuno-assay, GC/MS or LCMS at the Centralia, IL CWS 

from 2003-2008 as part of the VMP and AMP

Method
Page 27 of 39

EPA Question 2: “What caused/is causing the oscillating TCT levels in these systems?” 

CWS Name State PWSID Waiver Request 

Filed? 

Mt. Olive IL IL1170700 Yes 

Centralia Water Treatment Plant IL IL1214220 Yes 

Waverly IL IL1370450 Yes 

Coulterville Water Treatment Plant IL IL1570150 Yes

Bedford Water Department IN IN5247001 Yes 

Beloit Water Department KS KS2012301 Yes 

Defiance OH OH2000111 Yes 

Questions regarding TCT oscillations in certain CWS are explained mainly by the agricultural 

herbicide use pattern for corn and sorghum. For example, in studying herbicide concentrations 

in surface water in the Lake Erie Basin, Baker and Richards1 determined that peak atrazine 

concentrations were associated with storm events following herbicide application. Peaks in 

concentration were of short duration and typically followed by lower levels as the stream flow 

decreased. However, the peak concentrations are not necessarily proportional to peak flows of 

the stream. Atrazine is typically applied once as pre-emergenc e and generally no more than 

twice, with second being post emergent spray. As the cropping season progressed peak 

concentrations were reduced to less than or near detection limits in the mid to late crop season 

(Baker and Richards 1989). Precipitation (timing and amount, relative to application) also plays 

a key role in the temporal nature of these observed TCT levels and the relative importance of 

these effects will vary from year-to-year. This same pattern of herbicide transport and pulse in 

surface water concentrations was also reported and discussed by Thurman et al of the USGS2

 

1

 Baker, David. B. and Richards, R. P., 1989. Herbicide Concentration Patterns in Rivers Draining Intensively 

Cultivated Farmlands of Northwestern Ohio. pp.103-120. Water Quality Laboratory, Heidelberg College, Tiffin, 

Ohio. In: Pesticides in Terrestrial and Aquatic Environments, Proceedings of a National Research Conference, May 

11-112, 1989. Diana L. Weigmann, Editor. Virginia Water Resources Research Center, Virginia Polytechnic Institute 

and State University. 

2

 Thurman, E. M., Goolsby, D. A., Meyer, M. T., and Kolpin, D. W. 1991, Herbicides In Surface Waters of the 

Midwestern United States: The Effect of Spring Flush. Environmental Science and Technology, October 1991, pp. 

1794-1796. 
Page 28 of 39

Based on almost ten years of herbicide monitoring at seven stream/river sites with different 

sized watersheds in the Lake Erie Basin, Baker and Richards (1989) noted herbicide peak 

concentrations decreased as the stream order increased. In their study, the annual variability in 

concentrations decreased as the watershed size (and thus stream order increased). 

As Baker and Richards’ (1989) research showed, the seasonal use and occurrence of atrazine in 

surface water runoff causes an annual “oscillation” of TCT concentrations in surface water 

corresponding to spring/early summer runoff events. This is apparent in viewing the 90-day 

TCT and individual atrazine and TCT concentrations for Mt. Olive IL, Centralia IL, Waverly IL, 

Coulterville IL, Bedford IN, Beloit KS, and Defiance OH. As before, we have calculated and 

graphed 90-day TCT rolling averages in finished water using the EPA procedure used in the 

current EPA analysis as we understand it (GC/MS data only prior to August 2005) as well as 

using the complete data set (TCT calculated from IA, GC/MS and LC/MS data). In most 

instances, limiting the data set to GC/MS data produced an over-estimation of TCT values, and 

in many case significantly so. Although the oscillating pattern of TCT concentrations may still be 

observed, the magnitude of the fluctuation is often less than predicted using the partial data 

set selected by EPA. This effect is generally more pronounced in community water systems 

using a stream or river as the primary raw water source versus those systems that rely primarily 

on reservoirs. 

The following graphs (Figures 23 through 36) represent 90-day rolling averages for the CWS in 

the table above using both the partial data set selected by EPA (GC/MS, confirmation data set 

only with linear interpolation between analyses) and the full data set (TCT calculated from IA, 

GC/MS and LC/MS), calculated as previously discussed. It can be seen that in a few CWS, the 

oscillation is slightly exaggerated in the early years when the data set is limited to the GC/MS 

only samples, which as previously discussed tended to over-estimate maximum 90 day rolling 

averages. 
Page 29 of 39

0

1

2

3

4

5

6

7

8

9

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

concentration (ppb)

Figure 23

90-day TCT Rolling Averages in Finished Water Comparing Use of All Triazine Analytical 

Data to MS Method Only Data (With Interpolation), Mt. Olive, IL CWS 2003-2008

90-day TCT

(Full Data Set: IA, GC/MS, LC/MS Sample Results)

90-day TCT

(GC/MS and LC/MS Sample Results)

90-day TCT

(Partial Data Set: GC/MS and LC/MS with Linear Interpolation)

0

2

4

6

8

10

12

14

16

18

20

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Concentration (ppb)

Figure 24

Atrazine Plus Metabolites, Simazine, and Atrazine Plus Metabolites Plus Simazine in 

Finished Water at Old Lake, Mt Olive, IL CWS 2003-2008

Atz + Metab

(IA, GC/MS, LC/MS)

Simazine

(GC/MS, LC/MS) 

Atz+Metab+Sim

(GC/MS, LC/MS)
Page 30 of 39

0

1

2

3

4

5

6

7

8

9

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

90-day TCT Rolling Average (ppb)

Figure 25

90-day TCT Rolling Averages in Finished Water Comparing Use of All Triazine Analytical 

Data to MS Method Only Data (With Interpolation), Centralia, IL CWS 2003-2008

90-day TCT

(Full Data Set: IA, GC/MS, LC/MS Sample Results)

90-day TCT

(GC/MS and LC/MS Sample Results)

90-day TCT

(Partial Data Set: GC/MS and LC/MS with Linear Interpolation)

0

1

2

3

4

5

6

7

8

9

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Concentration (ppb)

Figure 26

Individual Sample Atrazine Plus Metabolites, Simazine, and Atrazine Plus Metabolites Plus 

Simazine (TCT) in Finished Water at 

Centralia, IL from 2003-2008

Atz + Metab

(IA, GC/MS, LC/MS)

Simazine

(GC/MS, LC/MS) 

Atz+Metab+Sim

(GC/MS, LC/MS)
Page 31 of 39

0

1

2

3

4

5

6

7

8

9

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Concentration (ppb)

Figure 27

90-day TCT Rolling Averages in Finished Water Comparing Use of All Triazine Analytical 

Data to MS Method Only Data (With Interpolation), Waverly, IL CWS 2003-2008

90-day TCT

(Full Data Set: IA, GC/MS, LC/MS Sample Results)

90-day TCT

(GC/MS and LC/MS Sample Results)

90-day TCT

(Partial Data Set: GC/MS and LC/MS with Linear Interpolation)

0

2

4

6

8

10

12

14

16

18

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Concentration (ppb)

Figure 28

Individual Sample Atrazine Plus Metabolites, Simazine, and Atrazine Plus Metabolites 

Plus Simazine (TCT) in Finished Water at 

Waverly, IL CWS 2003-2008

Atz + Metab

(IA, GC/MS, LC/MS)

Simazine

(GC/MS, LC/MS) 

Atz+Metab+Sim

(GC/MS, LC/MS)
Page 32 of 39

0

1

2

3

4

5

6

7

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Concentration (ppb)

Figure 29

90-day TCT Rolling Averages in Finished Water Comparing Use of All Triazine Analytical 

Data to MS Method Only Data (With Interpolation), Coulterville, IL CWS 2003-2008

90-day TCT

(Full Data Set: IA, GC/MS, LC/MS Sample Results)

90-day TCT

(GC/MS and LC/MS Sample Results)

90-day TCT

(Partial Data Set: GC/MS and LC/MS with Linear Interpolation)

0

2

4

6

8

10

12

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Concentration (ppb)

Figure 30

Atrazine Plus Metabolites, Simazine, and Atrazine Plus Metabolites Plus 

Simazine in Finished Water at Coulterville, IL CWS 2003-2008

Atz + Metab

(IA, GC/MS, LC/MS)

Simazine

(GC/MS, LC/MS) 

Atz+Metab+Sim

(GC/MS, LC/MS)
Page 33 of 39

0

1

2

3

4

5

6

7

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Concentration (ppb)

Figure 31

90-day TCT Rolling Averages in Finished Water Comparing Use of All Triazine Analytical 

Data to MS Method Only Data (With Interpolation), Bedford, IN CWS 2003-2008

90-day TCT

(Full Data Set: IA, GC/MS, LC/MS Sample Results)

90-day TCT

(GC/MS and LC/MS Sample Results)

90-day TCT

(Partial Data Set: GC/MS and LC/MS with Linear Interpolation)

0

5

10

15

20

25

30

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Concentration (ppb)

Figure 32

Atrazine Plus Metabolites, Simazine, and Atrazine Plus Metabolites Plus Simazine in 

Finished Water at Bedford, IN CWS 2003-2008

Atz + Metab

(IA, GC/MS, LC/MS)

Simazine

(GC/MS, LC/MS) 

Atz+Metab+Sim

(GC/MS, LC/MS)
Page 34 of 39

0

2

4

6

8

10

12

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Concentration (ppb)

Figure 33

90-day TCT Rolling Averages in Finished Water Comparing Use of All Triazine Analytical 

Data to MS Method Only Data (With Interpolation), Beloit, KS CWS 2003-2008

90-day TCT

(Full Data Set: IA, GC/MS, LC/MS Sample Results)

90-day TCT

(GC/MS and LC/MS Sample Results)

90-day TCT

(Partial Data Set: GC/MS and LC/MS with Linear Interpolation)

0

5

10

15

20

25

30

35

40

45

50

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Concentration (ppb)

Figure 34 

Atrazine Plus Metabolites, Simazine, and Atrazine Plus Metabolites Plus Simazine in 

Finished Water at Beloit, KS CWS 2003-2008

Atz + Metab

(IA, GC/MS, LC/MS)

Simazine

(GC/MS, LC/MS) 

Atz+Metab+Sim

(GC/MS, LC/MS)
Page 35 of 39

0

1

2

3

4

5

6

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Concentration (ppb)

Figure 35

90-day TCT Rolling Averages in Finished Water Comparing Use of All Triazine Analytical 

Data to MS Method Only Data (With Interpolation), 

Defiance, OH CWS 2003-2008

90-day TCT

(Full Data Set: IA, GC/MS, LC/MS Sample Results)

90-day TCT

(GC/MS and LC/MS Sample Results)

90-day TCT

(Partial Data Set: GC/MS and LC/MS with Linear Interpolation)

0

5

10

15

20

25

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Concentration (ppb)

Figure 36

Atrazine Plus Metabolites, Simazine, and Atrazine Plus Metabolites Plus 

Simazine in Finished Water at Defiance, OH CWS 2003-2008

Atz + Metab

(IA, GC/MS, LC/MS)

Simazine

(GC/MS, LC/MS) 

Atz+Metab+Sim

(GC/MS, LC/MS)

Question 3: What led to the increase of TCTs in Maryville MO from 2004-2005?

Syngenta Response: Available monitoring data for Maryville MO are listed by analytical 

methodology used in Table 13. None of 22 analyses in 2003 and 2 of 33 analyses in 2004 were 

confirmed using GC/MS methodology. In 2005, 7 samples were analyzed using the GC/MS 

method, 17 by the LC/MS method and 11 by IA. Using the partial data set selected by EPA 
Page 36 of 39

(GC/MS only) in 2004 and early 2005 results in an under-estimation of finished water 90-day 

TCT concentrations in the Marysville CWS (Table 13 and Figure 37). The GC/MS results for the 2 

samples in 2004 were below the initial immunoassay results, showing atrazine results of 0.71 

ppb on May 17, 2004 and 1.04 ppb on December 6, 2004. As previously mentioned, the IA 

method occasionally overestimated residues when. Examining the full data set (TCT calculated 

from IA, GC/MS and LC/MS) between 2003 and 2008 shows an annual maximum 90-day 

average TCT concentrations in finished water at the Maryville CWS have ranged from 2.4 to 4.4 

ppb. Over the six year monitoring period TCT concentrations have remained low and relatively 

constant. Individual finished water TCT concentrations have remained below 7 ppb for 

duration of the six – year monitoring period (Figure 38). These data do not indicate that there 

have been significant increases in TCT levels for Maryville over the monitoring period. 

Year Total Samples (n)

IA GC/MS LC/MS

2003 22 22 0 0

2004 33 31 2 0

2005 35 11 7 17

2006 35 0 0 35

2007 35 0 0 35

2008 30 0 0 30

Table 13

 Samples Analyzed by Immuno-assay, GC/MS or LCMS from the AMP 

at the Maryville, MO CWS from 2003-2008

Method
Page 37 of 39

0

2

4

6

8

10

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Concentration (ppb)

Figure 37

90-day TCT Rolling Averages in Finished Water Comparing Use of All Triazine Analytical 

Data to MS Method Only Data (With Interpolation), 

Maryville, MO CWS 2003-2008

90-day TCT

(Full Data Set: IA, GC/MS, LC/MS Sample Results)

90-day TCT

(GC/MS and LC/MS Sample Results)

90-day TCT

(Partial Data Set: GC/MS and LC/MS with Linear Interpolation)

0

1

2

3

4

5

6

7

8

9

10

Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Concentration (ppb)

Figure 38 

Atrazine Plus Metabolites, Simazine, and Atrazine Plus Metabolites Plus Simazine in 

Finished Water at Maryville CWS, MO CWS 2003-2008

Atz + Metab

(IA, GC/MS, LC/MS)

Simazine

(GC/MS, LC/MS) 

Atz+Metab+Sim

(GC/MS, LC/MS)
Page 38 of 39

EPA Question 4: Why are there no TCT data for 2007? Did the source water switch, or is 

there another reason? 

Vermont, IL 

Syngenta Response: TCT concentrations for 2007 at Vermont are available and have been 

previously provided to EPA. They are reported in Table 14 as additional reference. Please note 

that all 2007 samples were analyzed using LC/MS analytical methodology. 
Page 39 of 39

Date

Atz + Metab

(LC/MS)

Simazine

(LC/MS) 

Atz+Metab+Sim

(LC/MS)

01/02/07 0.4 0.05 0.45

01/16/07 0.4 0.05 0.45

01/29/07 0.33 0.03 0.36

02/12/07 0.33 0.03 0.36

02/26/07 0.33 0.03 0.36

03/12/07 0.33 0.1 0.43

03/26/07 0.33 0.03 0.36

04/02/07 0.33 0.03 0.36

04/09/07 0.33 0.03 0.36

04/16/07 0.33 0.03 0.36

04/23/07 0.33 0.03 0.36

04/30/07 2.52 0.03 2.55

05/07/07 2.84 0.03 2.87

05/14/07 1.77 0.03 1.8

05/21/07 2 0.03 2.03

05/29/07 1.44 0.03 1.47

06/04/07 1.52 0.03 1.55

06/11/07 1.29 0.03 1.32

06/18/07 1.08 0.03 1.11

06/25/07 0.98 0.03 1.01

07/02/07 1.35 0.03 1.38

07/09/07 1.77 0.03 1.8

07/16/07 0.66 0.03 0.69

07/23/07 0.83 0.03 0.86

07/30/07 1.12 0.03 1.15

08/13/07 0.89 0.03 0.92

08/27/07 0.7 0.03 0.73

09/10/07 0.63 0.03 0.66

09/24/07 0.63 0.03 0.66

10/09/07 0.42 0.03 0.45

10/22/07 0.61 0.03 0.64

11/05/07 0.92 0.03 0.95

11/19/07 0.95 0.03 0.98

12/03/07 1.04 0.03 1.07

12/17/07 0.55 0.03 0.58

Table 14

Atrazine, Metabolite and Simazine Concentrations in Finished Water 

From the Vermont, IL CWS and the Syngenta AMP, 2007