8277

• UCREFRP Catalog Number: 8277
• Author: Bauch, N. J. and N. E. Spahr.
• Title: Pesticides in Surface Waters of the Upper Colorado River Basin, Colorado, 1996-98.
• USFW Year: 2000.
• USFW - Doc Type: Water-Resources Investigations Report 00-4005,
• Copyright Material: NO

N
a Table 10. Summary of pesticide occurrence and concentrations for all 44 surface-water sites sampled in the UCOL study unit, October 1996 through January 1998
and May 1998
[>_, greater than or equal to; µg/L, micrograms per liter; MRL, method reporting limit, <, less than; E, estimated; --, method reporting limit greater than detection threshold; HPLC,
high-performance liquid
chromatography]

Number Percentage Percentage Concentration at indicated percentile
Maximum
Number of Percentage detected detected MRL (µ9L)
Pesticide of
detections
detected
?0.01
>_0.05
(µ9L) concentration
samples
(µ9L)
(µ9L) 10th 25th 50th 75th 90th (µ9L)
Atrazine 100 69 69 35 12 0.001 <0.001 <0.001 0.005 0.019 0.061 1.04
Alachlor 100 57 57 33 13 0.002 <0.002 <0.002 0.003 0.014 0.086 0.751
Metolachlor 100 46 46 23 10 0.002 <0.002 <0.002 <0.002 0.009 0.053 0.442
Deethylatrazine 100 37 37 5.0 0.0 0.002 <0.002 <0.002 <0.002 0.004 0.008 E 0.028
2,4-D 100 32 32 -- -- 0.035 <0.035 <0.035 <0.15 0.170 0.385 E 3.50
~ 10.15
o Cyanazine 100 30 30 14 4.0 0.004 <0.004 <0.004 <0.004 0.006 0.013 0.618
0
~,
DCPA
100
30
30
8.0
1.0
0.002
<0.002
<0.002
<0.002
0.002
0.007
0.109
a
o
Trifluralin
100
30
30
9.0
1.0
0.002
<0.002
<0.002
<0.002
0,003
0.007
0.051

EPTC 100 21 21 10 5.0 0.002 <0.002 <0.002 <0.002 <0.002 0.014 0.853
m
W Acetochlor 100 19 19 15 7.0 0.002 <0.002 <0.002 <0.002 <0.002 0.022 2.61
m
w
Carbofuran (HPLC)
98
19
19
--
--
0.028
<0.028
<0.028
<0.12
<0.12
0.447
E 1.80
n 10.12
,
Chlorpyrifos 100 13 13 2.0 0.0 0.004 <0.004 <0.004 <0.004 <0.004 0.005 0.029
0
d Benfluralin 100 10 10 0.0 0.0 0.002 <0.002 <0.002 <0.002 <0.002 0.002 0.009
a
Diazinon
100
8
8.0
3.0
1.0
0.002
<0.002
<0.002
<0.002
<0.002
<0.002
0.104
~ Pendimethalin 100 8 8.0 6.0 1.0 0.004 <0.004 <0.004 <0.004 <0.004 <0.004 0.099

Propargite 100 6 6.0 -- 3.0 0.013 <0.013 <0.013 <0.013 <0.013 <0.013 0.230

Simazine 100 5 5.0 5.0 1.0 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 0.065
Carbaryl (HPLC) 98 3 3.1 3.1 3.1 0.008 <0.008 <0.008 <0.008 <0.008 <0.008 0.780
Diuron 98 3 3.1 -- 1.0 0.02 <0.02 <0.02 <0.02 <0.02 <0.02 E 18.0
Azinphos-methyl 100 3 3.0 1.0 1.0 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 E 0.062
Dicamba 99 3 3.0 -- 3.0 0.035 <0.035 <0.035 <0.035 <0.035 <0.035 E 1.50
Ethalfluralin 100 3 3.0 0.0 0.0 0.004 <0.004 <0.004 <0.004 <0.004 <0.004 0.009
Terbufos 100 3 2.0 -- 0.0 0.013 <0.013 <0.013 <0.013 <0.013 <0.013 0.018
2,4-DB 100 2 2.0 -- -- 0.035 <0.035 <0.035 <0.035 <0.24 <0.24 0.830
Dieldrin 100 2 2.0 0.0 0.0 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 E 0.004
gamma-HCH 100 2 2.0 1.0 0.0 0.004 <0.004 <0.004 <0.004 <0.004 <0.004 0.012
Malathion 100 2 2.0 2.0 0.0 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 0.026
Metribuzin 100 2 2.0 1.0 0.0 0.004 <0.004 <0.004 <0.004 <0.004 <0.004 0.011