Final Stage 1 Report
Final Report Page 38 August 2007t
4.5.1.6 Atrazine
Atrazine data have been collected at the Mt. Olive raw water intake and the data are summarized in Table
4-8 and Table 4-9. The tables show that 61 samples were collected and 36 samples (59 percent) exceeded
the 3.0 μg/L drinking water supply standard. Figure 4-11 shows that observed atrazine concentrations
generally decrease throughout the sampling period.
Because these data were collected at the Mt. Olive raw water intake (which includes water from both Mt.
Olive Old Lake and Mt. Olive New Lake), it is not possible to associate the data directly with either lake.
As a result, data collected at the intake are presented for the Mt. Olive New Lake and the Mt. Olive Old
Lake and were used by IEPA in making the use support determination.
Table 4-8. Summary Statistics for Atrazine in Mt. Olive Raw Water Intake.
Parameter
Samples
(Count) Start End
Minimum
(μg/L)
Average
(μg/L)
Maximum
(μg/L) CV*
Atrazine 57 4/21/2003 12/20/2004 0.05 5.88 18.78 0.95
*CV = standard deviation/average
Table 4-9. Violations of the atrazine Drinking Water Standard in Mt. Olive Raw Water Intake.
Parameter
Samples
(Count)
Violations
(Count)
Percent
Violating
Samples (Count),
2000 to Present
Violations
(Count), 2000
to present
Percent
Violating,
2000 to
Present
Atrazine 57 32 56% 57 32 56%
0
2
4
6
8
10
12
14
16
18
20
Apr-03
May-03
Jun-03
Jul-03
Aug-03
Sep-03
Oct-03
Nov-03
Dec-03
Jan-04
Feb-04
Mar-04
Apr-04
May-04
Jun-04
Jul-04
Aug-04
Sep-04
Oct-04
Nov-04
Dec-04
Concentration (ug/L)
Atrazine DWS Standard
Figure 4-11. Atrazine Sampling Observations in the Mt. Olive Raw Water Intake.
