-------
A Review of Contaminant Occurrence in Public Water Systems
Table A-7.a. Summary of Contaminant Occurrence in Surface Water Systems from the
Unregulated Contaminant Monitoring Information System (URCIS).
Contaminant
Phase II/V Regulated Contaminants
Synthetic Organic Compounds
Dibromochloropropane (DBCP)
Ethyjene Dibromide (EDB)
Volatile Organic Compounds
1,1,1 -Thchloroethane
1 ,1 ,2-Trichloroethane
1 ,1 -Dichloroethene
1 ,2,4-Trichlorobenzene
1 ,2-Dichloroethane
1 ,2-Dichloropropane
Benzene
Carbon tetrachloride
Chlorobenzene
cis-1 ,2-Dichloroethylene
Ethyl benzene
Methylene chloride (Dichloromethane)
o-Dichlorobenzene
p-Dichlorobenzene
Styrene
Tetrachtoroethylene
Toluene
trans- 1 ,2-Dichloroethylene
Trichloroethene (Trichloroethylene)
Vinyl chloride
Xylenes (Total)
o-Xylene
M-Xylene
P-Xylene
Required Unregulated Contaminants
(nv) 1,3-Dichlorobenzene
1,1,1 ,2-Tetrachloroethane
1 ,2,3-Trichloropropane
1 .3-DichloroDrooane
Chloroethane
Chloromethane
Dibromo methane
o-Chlorotoluene
p-Chlorotoluene
Surface Water Systems
No. of
Analyses
6,211
5,517
7,603
8,892
7,743
6.837
7,541
9.373
7.101
7,534
9,291
8,852
9.168
9,034
9.053
7.429
8.928
9,500
9,165
9,3431
7,851
6,438
1,906
6,993
6,578
5,958
9,153
8.669
8.698
8.709
9.160
9,322
8,635
8,273
7,973
No. of
Systems
1,606
1,395
1,393
2,007
1.539
1,691
1,372
1.972
1,288
1,385
2.017
1.989
2.056
2.008
1.948
1.498
1,985
1,816
2,065
1,974
1,394
1,363
687
1.609
1.404
1,357
1,971
1,905
1,910
1.899
2.035
2,051
1,872
1,854
1,841
>MRL
N
41
35
78
36
36
12
25
15
32
70
68
36
88
238
19
46
28i
56
169
23
93
17
82
47
31
33
15
12
5
2
26
49
34
11
6
%
2.55%
2.51%
5.60%
1 .79%
2.34%
0.71%
1.82%
0.76%
2.48%
5.05%
3.37%
1.81%
4.28%
11.85%
0.98%
3.20%
1.41%
3.08%
8.18%
1.17%
6.67%
1.25%
11.94%
2.92%
2.21%
2.43%
0.76%
0.63%
0.26%
0.11%
1.28%
2.39%
1.82%
0.59%
0.33%
>0.5 MCL
N
18
22
1
6
10
0
7
0
%
>l
N
1.12%| 15
1.58% 19
0.07%
0.30%
0.65%
0.00%
0.51%
0.00%
11 i 0.85%
11
0
2
0
119
0
0
0
22
0
0
30
11
0
0.79%
0.00%
0.10%
0.00%
5.93%
0.00%
0.00%
, 0.00%
1.21%
0.00%
0.00%
2.15%
0.81%
0.00%
0
4
4
0
7
0
4
5
0
0
0
67
0
0
0
16
0
0
18
8
0
MCL"
%
0-93%
1.36%
0.00%
0.20%
0.26%
0.00%
0.51%
0.00%
0.31%
0.36%
0.00%
0.00%
0.00%
3.34%
0.00%
0.00%
0.00%
0.88%
0.00%
0.00%
1.29%
0.59%
0.00%
N/A
N/A
N/A
0
0
0
0.00%
0.00%
0.00%
0
0
0
0.00%
0.00%
0.00%
N/A
N/A
32
1.56%
20 1 0.98%
N/A
0
0
0.00%
0.00%
0
0
0.00%
0.00%
A-20
-------
A Review of Contaminant Occurrence in Public Water Systems
Table A-7.a. Summary of Contaminant Occurrence in Surface Water Systems from the
Unregulated Contaminant Monitoring Information System (URCIS) (Continued).
Contaminant
Discretionary Compounds
1 ,2.3-Trichlorobenzene
Surface Water Systems
No. of
Analyses
No. of
Systems
6,437 1,542
1,3,5-TrimethyJbenzene 6,154
Bromochlorornethane €.637
Diehlorodifluoromethane 6,933
isopropvlbenzene
n-Butvl benzene
n-Propylbenzene
p-lsopropyltoluene
sec-Butvlbenzene
6,314
6.483
6,467
6,060
6.216
tert-Butvlbenzene | 6,214
TricWorofluoromethane 7,353
cis-1 .3-DichloroDropene
Total 1.2-Dichloroethene
trans-1 .3-Dichioronropene
Other Reautated Contaminants
irornodichlorornethane
Brornoform
Chlorodibromometriane
Chloroform
Total THMs
Contaminant Candidate List
1 ,1.2,2-Tetrachloroethane
1,1-Oichloroethane
1 , 1 -Dichtorooropene
3,038
3.900
11.419
10,179
10,639
11,987
8,988
9.471
8,607
1.2.4-Trimetriylbenzene 6,276
2.2-DiohloroDroDane
Bromobenzene
Bromomethane
Hexachtorobutadiene
Naphthalene
Total 1.3-Dichlorooropene
8,802
6,928
9.298
5,958
6.466
3.771
1,524
1.538
1,744
1,524
1.523
>MRL
N
%
10: 0.65%
14! 0.92%
18
29
6
13
1.516! 5
1.435 3
1,489 3
1,489
1,792
953
1.073
2.611
2,146
2.378
2.736
2,020
2,040
1,899
1,519
1,905
1.878
2.039
1.538
1.620
947
1.17%
1.66%
0.39%
0.85%
0.33%
0.21%
0.20%
3! 0.20%
46 2.57%
14
14
2,113
474
1,535
2,341
21
39
8
21
5
11
27
10
, 33
r e
1.47%
1.30%
80.93%
22.09%
64.55%
85.56%
1.04%
1.91%
0.42%
1.38%
0.26%
0.59%
1.32%
0.65%
2.04%
0.63%
>0.5 MCL
N
%
>MCL*
N
%
N/A
N/A
2 1 0.13%
0
0.00%
1
0
0.07%
0.00%
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
63
2.65%
7[ 0.29%
N/A
N/A
N/A
N/A
N/A
N/A
N/A
5
7
2
0.25%
0.46%
0.12%
K
4
6
0
0.20%
0.39%
0.00%
I/A
N/A = There is no MCUHAL for this contaminant.
* % > MCL indicates the proportion erf systems with any
an MCL violation. An MCL violation occurs when the Ml
rewired bv the Drimacv State
3L is exceeded by the average
concentration value of tfte MCL; it does not necessarily indicate
results from lour quarterly samples or confirmation samples as
A-21
-------
A Review of Contaminant Occurrence in Public Water Systems
Table A-7.b. Summary of Contaminant Occurrence in Ground Water Systems from the
Unregulated Contaminant Monitoring Information System (URCIS).
Contaminant
Phase li/V Requlated Contaminants
Synthetic Organic Compounds
Dibromochloropropane (DBCP)
Ethylene Dibromide (EDB)
Volatile Organic Compounds
1,1,1-Trichloroethane
1,1.2-Trichloroethane
1,1-Dichloroethene
1 ,2,4-Trichlorobenzene
1 ,2-Dichloroethane
1 ,2-Dichloropropane
Benzene
Carbon tetrachloride
Chlorobenzene
cis-1 ,2-Dichloroethylene
Ethyl benzene
Methylene chloride (Dichloromethane)
o-Dichlorobenzene
p-Dichloro benzene
Styrene
Tetrachloroethylene
Toluene
trans- 1 ,2-Dichloroethylene
Trichloroethene (Trichtoroethylene)
Vinyl chloride
Xylenes (Total)
o-Xylene
M-Xylene
P-Xylene
Reauired Unreaulated Contaminants
(m-) 1 ,3-Dichlorobenzene
1 .1 ,1 ,2-Tetrachloroethane
1 ,2.3-TrichloroprDDane
1 ,3-Dichloropropane
Chloroethane
Chloromethane
Dibromomethane
o-Chlorotoluene
p-Chlorotoiuene
Ground Water Systems
No. of
Analyses
44,492
40,568
40.293
55,913
39,985
39,915
38,602
56,122
38,718
39,453
57,052
49.313
56,726
55,033
56.725
39,647
47,684
63,710
56.879
56,299
45,407
37.337
26,985
38.692
[ 33.628
27.364
58,780
49,387
49,810
49,269
57,469
58,214
48,437
44,052
42.912
No. of
Systems
11,730
10,579
14,697
18,625
14,592
12,349
14,640
18,286
14,403
14.622
18.714
15,434
18,825
18.053
18,673
14,668
15,327
18,808
18,870
18.653
14.695
14.479
8,913
13,076
10.484
9.219
19,127
15,702
16.139
15.702
18,892
18,964
15.323
14,516
14,416
>MRL
N
299
114
662
59
204
57
236
125
267
235
56
276
365
689
42
171
97
782
725
130
621
73
279
301
247
155
39
22
47
21
70
285
40
27
26
%
2.55%
1 .08%
>0.5 MCL
N
191
94
4.50% 13
0.32%! 12
1.40%! 66
0.46%
1.61%
0.68%
1 .85%
1.61%
0.30%
1 .79%
1.94%
3.82%
0.22%
1.17%
0.63%
4.16%
3.84%
0.70%
4.23%
0.50%
3.13%
2.30%
2.36%
1.68%
0.20%
0.14%
0.29%
0.13%
0.37%
1.50%
0.26%
0.19%
0.18%
0
65
34
99
71
1
17
2
220
0
2
1
353
5
3
270
38
0
%
1.63%
0.89%
0.09%
0.06%
0.45%
0.00%
0.44%
0.19%
0.69%
0.49%
0.01%
0.11%
0.01%
1.22%
0.00%
0.01%
0.01%
1.88%
0.03%
0.02%
1.84%
0.26%
0.00%
>MCL*
N
161J
73
6
5
37
0
37
16
63
40
1
8
0
125
0
1
0
229^
1
1
190
28
0
%
1.37%
0.69%
0.04%
0.03%
0.25%
0.00%
0.25%
0.09%
0.44%
0.27%
0.01%
0.05%
0.00%
0.69%
0.00%
0.01%
0.00%
1.22%
0.01%
0.01%
1.29%
0.19%
0.00%
N/A
N/A
N/A
0
0
2
0.00%
0.00%
0.01%
0
0
1
0.00%
0.00%
0.01%
N/A
N/A
144
0.76%
93
0.49%
N/A
0
0
0.00%
0.00%
0
0
0.00%
0.00%
A-22
-------
A Review of Coniaminam Occurrence in Public Water Systems
Table A-7.b. Summary of Contaminant Occurrence in Ground Water Systems from the
Unregulated Contaminant Monitoring Information System (URCIS) (Continued).
Contaminant
Discretionary Compounds
1 ,2,3-Trichlorobenzene
1 .3.5-Trimethvlbenzene
Bromochloromethane
Dichlorodifluoromethane
Ground Water Systems
No. of
Analyses
36,383
36,324
38,250
45,692
Isoproovlbenzene 37,526
n-Butvlbenzene 37,413
n-Propylbenzene 37,412
p-lsopropyttoluene
sec-Butylbenzene
tert-Butvlbenzene
Trichlorofluorometfiane
Other Not-Reaulated Contaminants
cis-1 ,3-Dichloropropene
Total 1,2-Dtchloroethene
trans- 1 ,3-Dichloroprooene
Other Regulated Contaminants
Bromodichloromethane
Bromoform
Chlorodibromometriane
Chloroform
Total THMs
. . ,
*ontaminant candidate List
1.1 ,2,2-Tetrachloroethane
1.1-DJchloroetriane
1 ,1 -Dichloropropene
1 ,2,4-Trimethvlbenzene
2,2-Dichloropropane
Bromobenzene
Bromomethane
Hexachtorobutadiene
Naphthalene
Total 1,3-DtetiloroproDene
36,196
36,436
36,442
47,691
22,845
24,227
49.848
49,719
49,776
52,083
58,339
59,044
37.206
48,534
48,930
58.536
37,286
38,837
26,235
No. of
Systems
11,920
11.736
1 1 ,925
14.994
11.840
11,827
11.791
11.308
11.428
11.435
15,725
8.707
9.280
18.443
18,262
18,337
18,771
19.070
19.202
11.820
15,497
15.225
18.838
11.334
12.336
8.404
>MRL
N
54
86
55
223
41
37
43
32
29
24
243
45
15
2,931
1.484
2.431
4.483
80
278
110
25
29
140
36
146
14
%
0.45%
0.73%
0.46%
1.49%
>0.,
N
>MCL
%
>MCL*
N
%
N/A
N/A
6
0
0.05%
0.00%
3| 0.03%
oi 0.00%
0.35% N/A
0.31%
0.36%
0.28%
0.25%
0.21%
1.55%
0.52%
0.16%
15.89%
8.13%
13.26%
23.88%
N/A
N/A
N/A
N/A
N/A
N/A
N/A
t
N/A
N/A
N/A
26
0.14%
4
0.02%
N/A
I
0.42%
1.45%
0.93%
0.16%
0.19%
0.74%1
0.32%
1.18%
0.17%J
N/A
N/A
N/A
N/A
N/A
N/A
26
13
12
0.14%
0.11%
0.10%
15
6
4
0.08%
0.05%
0.03%
N/A
N/A = There is no MCUHAL for this contaminant.
• % > MCL indicates the proportion of systems with any analytical results exceeding the concentration value of the MCL; it does not necessarily
indicate an MCL violation. An MCL violation occurs when the MCL is exceeded by the average results from four quarterly samples or confirmation
saffiotes a&jeouired bv the orimacv State.
A-23
-------
APPENDIX B
USGS Studies Reviewed for Contaminant Occurrence Information.
-------
-------
USGS STUDIES REVIEWED FOR CONTAMINANT OCCURRENCE INFORMATION
Adamski, J. U.S. Department of the Interior. Nitrate and Pesticides in Ground Water of the
Ozark Plateaus in Arkansas, Kansas, Missouri, and Oklahoma. Fact Sheet # 182-96,
U.S. Geological Survey. 1997.
Adamski, J. U.S. Department of the Interior. Nutrients and Pesticides in Ground Water of the
Ozark Plateaus in Arkansas, Kansas, Missouri, and Oklahoma. Water Resources
Investigations Report # 96-4313, U.S. Geological Survey. 1997.
Anderolm, S.K., MJ. Radell, and S.F. Richey. U.S. Department of the Interior. Water Quality
Assessment of the Rio Grande Valley Study Unit, Colorado, New Mexico and Texas--
Analysis of Selected Nutrient, Suspended-Sediment, and Pesticide Data. Water
Resources Investigations Report # 94-4061, U.S. Geological Survey. 1995.
Ator, S.W., J.D. Blomquist, J.W. Brakebill, J.M. Denis, MJ. Ferrari, C.V. Miller, and H. Zappia.
U.S. Department of the Interior. Water Quality in the Potomac River Basin; Maryland,
Pennsylvania, Virginia, West Virginia, and the District of Columbia. Circular 1166, US
Geological Survey. 1998.
Ator, S.W. and MJ. Ferrari. U.S. Department of the Interior. Nitrate and Selected Pesticides in
Ground Water of the Mid-Atlantic Region. Water Resources Investigations Report 97-
4139, United States Geological Survey. 1997.
Barbash, I.E. U.S. Department of the Interior. Pesticides in Ground Water, Current
Understanding of Distribution and Major Influences. Fact Sheet 244-95, US Geological
Survey. 1996.
Barbash, J.E., and E.A. Resek. Pesticides in Ground Water, volume two of the series Pesticides
in the Hvdrologic System. Ann Arbor Press, Inc., Chelsea, Michigan. 1996.
Battaglin, W., and L. Hay. "Effects of Sampling Strategies on Estimates of Annual Mean
Herbicide Concentrations in Midwestern Rivers." Environmental Science & Technology.
30:889-896. 1996.
Battaglin, W., and D. Goolsby. "Regression Models of Herbicide Concentrations in Outflow
from Reserviors in the Midwestern USA, 1992-1993." Journal of the American Water
Works Association. 1369:34-6. 1998.
Berndt, M.P., H.H. Hatzell, C.A. Crandall, M. Turtora, J.R. Pittman, and E.T. Oaksford. U.S.
Department of the Interior. Water Quality in the Georgia-Florida Coastal Plain, Georgia
and Florida, 1992-1996. Circular 1151, U.S. Geological Survey. 1998.
B-l
-------
A Review of Contaminant Occurrence in Public Water Systems
Bevans, H.E., M.S. Lico, and S.J. Lawrence. U.S. Department of the Interior. Water Quality in
the Las Vegas Valley Area and the Carson and Truckee River Basins; Nevada and
California. Circular 1170, US Geological Survey. 1998.
Brown, M.F. U.S. Department of the Interior. Water-Quality Assessment of the Trinity River
Basin, Texas • Pesticides in a Coastal Prairie Agricultural Area. Open File Report # 96-
124, U.S. Geological Survey. February 1996.
Brown, M.F. U.S. Department of the Interior. Water-Quality Assessment of the Trinity River
Basin, Texas - Pesticides in a Suburban Watershed, Arlington, 1993-94. Fact Sheet #
159-95, U.S. Geological Survey. June 1995.
Burkart, M.R. and D.W. Kolpin. "Hydrologic and Land-Use Factors Associated with Herbicides
and Nitrate in Near-Surf ace Aquifers." Journal of Environmental Quality. 22(4): 646-
656. 1993.
Clark, G.M. U.S. Department of the Interior. Assessment of Nutrients, Suspended Sediment, and
Pesticides in Surface Water of the Upper Snake River Basin, Idaho and Western
Wyoming, Water Years 1991-95. Water Resources Investigations Report # 97-4020, U.S.
Geological Survey. 1997.
Clark, G.M. U.S. Department of the Interior. Occurrence and Flux of Selected Pesticides in
Surface Water of the Upper Snake River Basin, Idaho and Western Wyoming. Water
Resources Investigations Report # 97-4020, U.S. Geological Survey. 1997.
Clark, G.M., T.R. Maret, M.G. Rupert, M.A. Maupin, W.H. Low, and D.S. Ott. U.S.
Department of the Interior. Water Quality in the Upper Snake River Basin, Idaho and
Wyoming, 1992-95. Circular # 1160, U.S. Geological Survey. 1998.
Coupe, R.H., D.A. Goolsby, J.L. Iverson, D.J. Markovchik, and S.D. Zaugg. U.S. Department of
the Interior. Pesticide, Nutrient, Water-Discharge, and Physical-Property Data for the
Mississippi River and Some of Its Tributaries, April 1991-September 1992. Open File
Report 93-657, U.S. Geological Survey. 1995.
Crepeau, K.L., K.M. Kuivila, and J.L. Domagalski. U.S. Department of the Interior.
"Concentrations of Dissolved Rice Pesticides in the Colusa Basin Drain and Sacramento
River, CA, 1990-1992." In USGS Toxic Substances Hydrology Program-Proceedings of
the Technical Meeting, Colorado Springs, CO, September 20-24, 1993, edited by D.W.
Morganwalp and D.A. Aronson, p. 711-718. Water Resources Investigation Report 94-
4015, U.S. Geological Survey. 1996.
Dubrovsky, N. M., C.R. Kratzer, L.R. Brown, J.M. Gronberg, and K. R. Burow. U.S.
Department of the Interior. Water Quality in the San Joaquin-Tulare basins; California,
Circular 1159, US Geological Survey. 1998.
Fenelon, J.M. U.S. Department of the Interior. Water Quality in the White River Basin: Indiana.
Circular 1150, US Geological Survey. 1998.
B-2
-------
A Review of Contaminant Occurrence in Public Water Systems
Fisher, G.T. U.S. Department of the Interior. Selected Herbicides in Major Streams in the
Potomac River Basin Upstream from Washington. NAWQA Fact Sheet 107-95, U.S.
Geological Survey. 1995.
Frick, E.A., D.J. Hippe, G.R. Buell, C.A. Couch, E.H. Hopkins, DJ. Wangsness, and J.W.
Garrett. U.S. Department of the Interior. Water Quality in the Apalachicola-
Chattahoochee-Flint River Basin. Circular 1164, US Geological Survey. 1998.
Gilliom, R.J., W.M. Alley, and M.E. Gurtz. U.S. Department of the Interior. Design of the
National Water-Quality Assessment Program: Occurrence and Distribution of Water-
Quality Conditions. Circular 1112, US Geological Survey. 1995.
Goolsby, D.A. and W.A. Battaglin. "Occurrence and Distribution of Pesticides in Rivers of the
Midwestern United States." Chapter 16 in M.L. Leng, E.M.K. Leovey, and P.L. Zubkoff,
eds., Agrochemical Environmental Fate; State of the An. American Chemical Society.
Washington, DC. April, 1995.
Goolsby, D.A., R.C. Coupe, and DJ. Markovchick. U.S. Department of the Interior.
Distribution of Selected Herbicides and Nitrate in the Mississippi River and its Major
Tributaries, April through June 1991. Water Investigations Report 91-4163, U.S.
Geological Survey. 1991.
Goolsby, D.A. and W.E. Pereira. U.S. Department of the Interior. "Pesticides in the Mississippi
River." In R.H. Meade, ed., Contaminants in the Mississippi River. Circular 1133, U.S.
Geological Survey. 1995.
Graffy, E.A., D.R. Helsel, and D.K. Mueller. U.S. Department of the Interior. Nutrients in the
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Kalkhoff, S.J., D.W. Kolpin, E.M. Thurman, I. Ferrer, and D. Barcelo. "Degradation of
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"Occurrence of Selected Herbicides and Herbicide Degradation Products in Iowa's
Ground Water, 1995." Ground Water. 35-4: 679-687. 1997.
Kolpin, D.W., E.M. Thurman, and D.A. Goolsby. "Occurrence of Selected Pesticides and Their
Metabolites in Near-Surface Aquifers of the Midwestern United States." Environmental
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Kolpin, D.W. "Agricultural Chemicals in Ground Water of the Midwestern U.S.: Relations to
Land Use." Journal of Environmental Quality. 26(4). 1997.
Kolpin, D.W., J.E. Barbash, and R. J. Gilliom. "Occurrence of Pesticides in Shallow
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Kolpin, D.W., M.R. Burkart, and E.M. Thurman. U.S. Department of the Interior. Herbicides
and Nitrate in Near-Surface Aquifers in the Midcontinental United States 1991. Water
Supply Paper 2413, US Geological Survey. 1994.
Kolpin, D.W., G.R. Hallberg, D.A. Sneck-Fahrer, and R.D. Libra. U.S. Department of the
Interior. Agricultural Chemicals in Iowa's Ground Water, 1982-95—What are the
Trends? Fact Sheet 116-97, US Geological Survey. 1997.
Kolpin, D.W., PJ. Squillance, J.S. Zogorski, and I.E. Barbash. "Pesticides and Volatile Organic
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Kolpin, D.W., E.M. Thurman, and D.A. Goolsby. "Occurrence of Selected Pesticides and Their
Metabolites in Near-Surface Aquifers of the Midwestern United States." Environmental
Science & Technology. 30(1): 335-340. 1996.
Koterba, M.T., W.S.L. Banks, and R.J. Shedlock. "Pesticides in Shallow Ground Water in the
Delmarva Peninsula." Journal of Environmental Quality. 22: 500-518. 1993
Land, L.F. U.S. Department of the Interior. Water-Quality Assessment of the Trinity River
Basin, Texas - Nutrients and Pesticides in the Watersheds ofRichland and Chambers
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A Review of Contaminant Occurrence in Public Water Systems
Creeks, 1993-95. Water Resources Investigations Report # 97-4132, U.S. Geological
Survey. 1997.
Land, L.F. U.S. Department of the Interior. Water-Quality Assessment of the Trinity River
Basin, Texas - Pesticides in Urban and Agricultural Streams, 1993-95. Fact Sheet # 178-
96, U.S. Geological Survey. July 1996.
Land, L.F. and M.F. Brown. U.S. Department of the Interior. Water-Quality Assessment of the
Trinity River Basin, Texas - Pesticides in Streams Draining an Urban and an
Agricultural Area, 1993-95. Water Resources Investigations Report # 96-4114, U.S.
Geological Survey. 1995.
Land, L.F. U.S. Department of the Interior. Water-Quality in the Trinity River Basin, Texas -
1992-95. Circular #1171, U.S. Geological Survey. 1998.
Larson, S.J., R.J. Gilliom, and P.D. Capel. U.S. Department of the Interior. Pesticides in
Streams of the United States — Initial Results from the National Water Quality
Assessment Program. U.S. Geological Survey. Water-Resources Investigations Report
98-4222, 92 p. 1999.
Larson, S.J., P.D. Capel, and M.S. Majewski. Pesticides in Surface Waters, volume three of the
series Pesticides in the Hvdrologic System. Ann Arbor Press, Inc., Chelsea, Michigan.
1997.
Larson, S.J., P.D. Capel, and M.S. Majewski. "Analysis of Key Topics — Sources, Behavior, and
Transport." Chap. 5 in Pesticides in Surface Waters, volume three of the series Pesticides
in the Hvdrologic System. Ann Arbor Press, Inc., Chelsea, Michigan. 1997.
Leahy, P.P. and T.H. Thompson. U.S. Department of the Interior. The National Water-Quality
Assessment Program. Open-File Report 94-70, US Geological Survey. 1994.
Levings, G.W., D.F. Healey, S.F. Richey, and L.F. Carter. U.S. Department of the Interior.
Water Quality in the Rio Grande Valley, Colorado, New Mexico, and Texas, 1992-95.
Circular # 1162, U.S. Geological Survey. 1998.
Lindsey, B.D., K.J. Breen, M.D. Bilger, and R.A. Brightbill. U.S. Department of the Interior.
Water Quality in the Lower Susquehanna River Basin; Pennsylvania and Maryland.
Circular 1168, US Geological Survey. 1998.
Lopes, T.J. and D.A. Bender. U.S; Department of the Interior. "Nonpoint Sources of Volatile
Organic Compounds in Urban Areas - Relative Importance of Land Surfaces and Air."
Environmental Pollution. 1998. In Press.
Lopes, T.J., E.T. Furlong, and J.W. Pritt. "Occurrence and Distribution of Semivolatile Organic
Compounds in Stream Bed Sediments, United States, 1992-95." Environmental
Toxicology and Risk Assessment. Volume 7. American Society for Testing and
Materials. 1998.
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A Review of Contaminant Occurrence in Public Water Systems
Majewski, M.S., and P.D. Capel. Pesticides in the Atmosphere, volume one of the series
Pesticides in the Hvdrologic System. Ann Arbor Press, Inc., Chelsea, Michigan. 1995.
Nolan, B.T. and B.C. Ruddy. U.S. Department of the Interior. Nitrate in Ground Waters of the
United States-Assessing Risk. Fact Sheet FS-092-96, US Geological Survey. 1996.
Oaksford, E.T. U.S. Department of the Interior. National Water-Quality Assessment Program-
Preliminary Results: Agricultural Chemicals in the Suwannee River Basin, Georgia-
Florida Coastal Plain Study Unit. Open-File Report 94-103, U.S. Geological Survey.
1994.
Ohio Environmental Protection Agency. Pesticide Special Study. Division of Drinking and
Ground Waters. Columbus, 1998. Available on internet at
http://www.epa.state.oh.us/ddagw/pestspst.html.
Petersen, J.C., J.C. Adamski, J.V. Davis, S.R. Femmer, D.A. Freiwald, and R.L. Joseph. U.S.
Department of the Interior. Water Quality of the Ozark Plateaus; Arkansas, Kansas,
Missouri, and Oklahoma. Circular 1158, US Geological Survey. 1998.
Phillips, P.J., and D.W. Hanchar. U.S. Department of the Interior. Water-Quality Assessment of
the Hudson River Basin in New York and Adjacent States: Analysis of Available Nutrient,
Pesticide, Volatile Organic Compound, and Suspended Sediment Data, 1970-1990.
Water-Resources Investigations Report 96-4065, U.S. Geological Survey. 1996.
Puckett, L. J. U.S. Department of the Interior. Nonpoint and Point Sources of Nitrogen in Major
Watersheds of the United States. Water Resources Investigation Report 94-4001 and Fact
Sheet, US Geological Survey. 1996.
Reutter, D.C. U.S. Department of the Interior. Water-Quality Assessment of the Trinity River
Basin, Texas - Well and Water-Quality Data From the Outcrop of the Woodbine Aquifer
in Urban Tarrant County, 1993. Open File Report # 96-413, U.S. Geological Survey.
1996.
Rupert, M.G. U.S. Department of the Interior. Analysis of Data on Nutrients and Organic
Compounds in Groundwater in the Upper Snake River Basin, Idaho and Western
Wyoming, 1980-91. Water Resources Investigations Report # 94^135, U.S. Geological
Survey. 1994.
Rupert, M.G. U.S. Department of the Interior. Major Sources of Nitrogen Input and Loss in the
Upper Snake River Basin, Idaho and Western Wyoming, 1990. Water Resources
Investigations Report # 96-4008, U.S. Geological Survey. 1996.
Rupert, M.G. U.S. Department of the Interior. Nitrate in Ground Water of the Upper Snake
River Basin, Idaho and Western Wyoming, 1991-95. Water Resources Investigations
Report # 97^174, U.S. Geological Survey. 1997.
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A Review of Contaminant Occurrence in Public Water Systems
Ryker, S.J. and A.K. Williamson. U.S. Department of the Interior. Pesticides in Public Supply
Wells of the Central Columbia Plateau. Fact Sheet 205-96, U.S. Geological Survey.
October 1996.
Ryker, S.J. and A.K. Williamson. U.S. Department of the Interior. Pesticides in Public Supply
Wells of Washington State. Fact Sheet 122-96, U.S. Geological Survey. May 1996.
Schaap, B.D., and S.M. Linhart. U.S. Department of the Interior. Quality of Ground Water Used
for Selected Municipal Water Supplies in Iowa, 1982-96 Water Years. Open-File Report
98-3, U.S. Geological Survey. May 1998.
Scribner, E.A., D.A. Goolsby, E.M. Thurman, M.T. Meyer, and W.A. Battaglin. U.S.
Department of the Interior. Concentrations of Selected Herbicides, Herbicide
Metabolites, and Nutrients in Outflow from Selected Midwestern Reservoirs, April 1992
Through September 1993. Open File Report 96-363, U.S. Geological Survey. 1996.
Scribner, E.A., D.A. Goolsby, E. M. Thurman, M.T. Meyer, and M.L. Pomes. U.S. Department
of the Interior. Concentrations of Selected Herbicides, Two Triazine Metabolites, and
Nutrients in Storm Runoff from Nine Stream Basins in the Midwestern United States,
1990-1992. Open File Report 94-396, U.S. Geological Survey. 1994.
Shipp, A. U.S. Department of the Interior. Water-Quality Assessment of the Trinity River Basin,
Texas - Pesticide Occurrence in Streams, Winter and Spring -1994. Fact Sheet #160-95,
U.S. Geological Survey. June 1995.
Spruil, T.B., D.A. Harned, P.M. Ruhl, J.L. Eimers, G. McMahon, K.E. Smith, D.R. Galeone, and
M.D. Woodside. U.S. Department of the Interior. Water Quality in the Albemarle-
Pamlico Drainage Basin; North Carolina and Virginia. Circular 1157, US Geological
Survey. 1998.
Squillance, P.J., D.A. Pope, and C.V. Price. U.S. Department of the Interior. Occurrence of the
Gasoline Additive MTBE in Shallow Ground Water in Urban and Agricultural Areas.
Fact Sheet 114-95, U.S. Geological Survey. 1996.
Thurman, E.M., D.A. Goolsby, M.T. Meyer, and D.W. Kolpin. "Herbicides in Surface Waters of
the Midwestern United States: The Effect of Spring Flush." Environmental Science &
Technology. 25: 1794-1796. 1991.
U.S. Department of the Interior. National Synthesis: Pesticides in Ground Water. Fact Sheet FS
244-95, US Geological Survey. 1995.
U.S. Department of the Interior. Nutrients in the Nation's Waters—Too Much of a Good Thing?
Circular 1136, U.S. Geological Survey. 1996.
U.S. Department of the Interior. Pesticides in Surface and Ground Water of the United States:
Preliminary Results of the National Water Quality Assessment Program (NAWQA).
Pesticide National Synthesis Project, U.S. Geological Survey. 1998.
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A Review of Contaminant Occurrence in Public Water Systems
U.S. Department of the Interior. Pesticides in Surface Waters, Current Understanding of
Distribution and Major Influences. Fact Sheet 039-97, US Geological Survey. 1997.
U.S. Department of the Interior. VOCs in Ground Water of the United States: Preliminary
Results of the National Water Quality Assessment Program (NAWQA). VOC National
Synthesis Project, U.S. Geological Survey. 1998.
Vowinkel, E.F., R.M. Clawges, D.E. Buxton, D.A. Stedfast, and J.B. Louis. U.S. Department of
the Interior. Vulnerability of Public Drinking Water Supplies in New Jersey to Pesticides.
Fact Sheet 165-96, U.S. Geological Survey. 1996.
Wagner, R.J. J.C. Ebbert, and L.M. Roberts. U.S. Department of the Interior. Are Agricultural
Pesticides in Surface Waters of the Central Columbia Plateau? Fact Sheet # 241-95,
U.S. Geological Survey. 1995.
Wagner, R.J., J.C. Ebbert, L.M. Roberts, and S.J. Ryker. U.S. Department of the Interior.
Agricultural Pesticide Applications and Observed Concentrations in Surface Waters from
Four Drainage Basins in the Central Columbia Plateau, Washington, and Idaho. Water-
Resources Investigations Report 95-4285, U.S. Geological Survey. 1996.
Wall, G.R. and P.J. Phillips. U.S. Department of the Interior. Pesticides in Surface Waters of
the Hudson River Basin, New York and Adjacent States. Fact Sheet 238-96, US
Geological Survey. April 1997.
Wall, G.R., K. Riva-Murray, and P.J. Phillips. U.S. Department of the Interior. Water Quality in
the Hudson River Basin; New York and Adjacent States. Circular 1165, US Geological
Survey. 1998.
Washington Department of Health. Results of the Areawide Groundwater Monitoring Project.
Division of Drinking Water. Spring 1995.
Williamson, A.K., M.D. Munn, S.J. Ryker, R.J. Wagner, J.C. Ebbert, and A.M. Vanderpool.
U.S. Department of the Interior. Water Quality of the Columbia River Plateau,
Washington and Idaho. Circular 1144, US Geological Survey. 1998.
Zogorski, J. U.S. Department of the Interior. VOCs in Ground Water of the U. S.: Preliminary
Results of the NAWQA Program. Fact Sheet, US Geological Survey. 1998.
B-8
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APPENDIX C
General Data Quality Issues
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GENERAL DATA QUALITY ISSUES
To add perspective to the types of data quality issues encountered while working with the
occurrence data, some of the most common concerns are outlined below. While this is far from a
complete list of all the quality issues encountered, it should provide some idea of the various
complexities and complications involved in preparing the data.
Every State database contained unique data elements or a unique treatment of common elements.
Even after initial screening and conversion, factors were always uncovered during data analysis.
These were resolved in consultation with the State or data source. As a general rale, when errors
or ambiguities in various data elements could not be resolved, the observation was eliminated
from the analysis to avoid aberrant results. These observations made up only a very small
portion of the large number of records included in most data sets.
Structure of the Data
Most of the data sets are "vertically" designed, meaning there is one column for the system
identification number, one column for the date sampled, one column for the name of the
contaminant analyzed, one column for the results, etc. Other data sets are "horizontally"
designed, meaning there is one column for the system identification number and multiple
columns for the contaminants analyzed (each contaminant has a separate column). The results
for each contaminant are thus displayed along a single data row under the appropriate
contaminant heading. A horizontal data structure is far more difficult to analyze in the manner
necessary for this study and requires extensive processing to transform into a more suitable
vertical structure.
File Format
Files which were submitted in CSV (comma separated values) format were problematic if proper
care was not taken to exclude or modify data fields (usually text fields) which might contain
commas within them (for example, a field holding the address of a water system might contain
one or more commas). This field would often separate into two or more columns as the
computer read the file. Unless every observation contained the same number of text commas
within each field, the following data fields would no longer line up by column between
observations. Making the necessary adjustments to allow the computer to properly recognize and
process the correct data fields is a tedious and time intensive task, even with the use of
specialized programs.
Multiple Data Sets
The size and number of data sets required to make up a complete occurrence database for a State
can vary considerably. While some States maintain one database for all water system monitoring
results, it is not unusual for a State to keep a number of databases for various data subsets (e.g., a
separate database for each of the contaminant groups - lOCs, SOCs, and VOCs). Other States
have very elaborate subsets consisting of multiple (10 or more) separate data sets for all of the
compliance data for the State. Sometimes each subset will have a unique format and structure
and require significant formatting before it is compatible with the rest of the State data. Many
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A Review of Contaminant Occurrence in Public Water Systems
States have an individual data manager for each of the contaminant groups and coordinating data
transfer requires communication with more than one contact person.
Contaminant Codes
Analytes were identified by a variety of codes including EPA codes, CAS numbers, STORET
codes (which might have multiple codes for a given contaminant), State-specific or laboratory-
specific codes, or by chemical name. In every case where a contaminant was identified by any
system other than EPA codes, the proper EPA contaminant designation was found and added to
the record.
Some States have special coding systems for contaminants that are covered under the same
analytical method. One of the most common systems summarizes the results of a single method
with an 'ND' or zero for all contaminants not detected and individual observations only for those
contaminants with a positive result. This system is best illustrated using the 21 VOCs covered
under method 502.2 as an example. If none of the 21 VOCs were detected, a State might enter
'21 VOCs' in the contaminant column and '0' in the results column of a single observation. If
one or more of the 21 VOCs were detected, these individual contaminants would be entered in
the contaminant column and the value they were detected at would be entered in the results
column of individual observations. It is assumed that every contaminant not recorded
individually was tested for and not detected. Although the example above may seem
straightforward, the rules can become complicated. It is not unusual to find caveats in the
database which need to be further defined by the State before analysis can begin. This is done
differently between States, and it is often not entirely consistent within a State data set.
Reporting non-Detections
There are numerous ways that States report non-detections in their data systems. Some States
report a value of zero when a contaminant is not detected, others have a column in which they
enter a less-than sign and then enter the method detection limit or reporting level in the results
column. A third common method for reporting no detects is the inclusion of a separate text
variable that will read *ND'. A result value of ND would be converted to zero for the purposes
of this study, while less-than values were kept as they are to provide a sense of the various
MRL/MDLs.
Units
States differ in the units they use to enter contaminant concentration results and, at times, the
reporting units change within a State. The most common unit for reporting results is in
milligrams per liter, but at times only the SOCs are reported in milligrams per liter and the rest of
the database will be in micrograms per liter. In some cases, units are not identified in a data set.
Other Data
Most of the databases coming from the States are not designed for data analysis and are generally
"electronic filing cabinets." The databases contain special sampling data, raw water data,
compliance data, and other sampling data. To analyze only the compliance data, it is necessary
to understand the coding system the State uses to distinguish the compliance sampling from the
other types of sampling. Most coding systems are unique to each State.
C-2
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APPENDIX D
Summary Tables V.A.I through V.A.8.
See text for details.
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A Review of Contaminant Occurrence in Public Water Systems
Table V.A.1. Summary of the percentage of systems with detections (>MRL) and exceedances
(>MCL*) of selected contaminants, comparing ground-water supplied, community-water systems
and non-transient, non-cornmunity water systems in Michigan.
Contaminant
SOCs
2,4-D
Atrazine
Benzo[a]pyrene
Carbofuran (Furadan)
Ethylene Dibromide (EDB)
Glyphosate (Roundup)
Simazine
VOCs
Benzene
Styrene
Tetrachloroethylene
Vinyl Chloride
XyJenes (Total)
CWSs
Percent > MRL
0.0%
0.3%
0.0%
0.0%
0.0%
0.0%
0.3%
0.9%
8.1%
1.8%
0.2%
1.8%
Percent > MCL*
0.0%
0.1%
0.0%
0.0%
0.0%
0.0%
0.0%
0.2%
0.0%
0.2%
0.0%
0.1%
NTNCWSs
Percent > MRL
0.0%
0.4%
0.0%
0.0%
0.0%
0.1%
0.9%
1.5%
0.6%
0.0%
1.6%
Percent > MCL*
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.3%
0.0%
0.1%
0.0%
0.0%
* % > MCL indicates the proportion of systems with any analytical results exceeding the concentration value of the MCL: it does not
necessarily indicate an MCL violation. An MCL violation occurs when the MCL is exceeded by the average results from four quarterly samples
or confirmation samples as required by the primacy State.
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A Review of Contaminant Occurrence in Public Water Systems
Table V.A.2. Summary of the percentage of systems with detections (>MRL) of selected
contaminants, comparing ground-water and surface-water supplied systems, by size of system
(population served categories), for a high-occurrence state.
Contaminant
Population Served
<500
500-3^00
3,301-10,000
10,001-50,000
> 50,000
Surface Water (% > MRL)
lOCs
Barium
Cadmium
Mercury
SOCs
2,4-D
Atrazine
Benzo[a]pyrene
Carbofuran (Furadan)
Ethylene Dibromide (EDB)
Glyphosate (Roundup)
VOCs
Benzene
Styrene
Tetrachloroethylene
Vinyl Chloride
Xytenes (Total)
100.0%
20.0%
0.0%
44.4%
100.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
22.2%
100.0%
0.0%
3.2%
65.8%
100.0%
0.0%
5.3%
2.6%
0.0%
5.1%
2.6%
2.6%
2.6%
17.9%
100.0%
0.0%
0.0%
53.8%
96.2%
0.0%
0.0%
20.0%
0.0%
33.3% j
26.7%
30.0%
23.3%
43.3%
100.0%
0.0%
0.0%
29.6%
96.3%
0.0%
0.0%
10.7%
0.0%
17.9%
17.9%
25.0%
17.9%
32.1%
100.0%
0.0%
0.0%
44.4%
55.6%
11.1%
0.0%
9.1%
0.0%
27.3%
27.3%
18.2%
27.3%
27.3%
Ground Water (% > MRL)
IOCS
Barium
Cadmium
Mercury
SOCs
2,4-D
Atrazine
Benzo[a]pyrene
Carbofuran (Furadan)
Ethylene Dibromide (EDB)
Glyphosate (Roundup)
VOCs
Benzene
Styrene
Tetrachloroethylene
Vinyl Chloride
Xylenes (Total)
98.2%
0.0%
0.0%
1.3%
2.5%
0.6%
0.2%
0.6%
0.0%
1.6%
3.3%
2.2%
1.6%
11.1%
98.6%
4.2%
1.9%
5.3%
11.3%
0.0%
0.0%
0-9%
0.0%
4.1%
4.4%
5.1%
2.1%
18.4%
95.2%
0.0%
0.0%
6.0%
12.0%
0.0%
0.0%
3.8%
0.0%
13.3%
10.5%
16.2%
11.4%
19.4%
90.9%
0.0%
0.0%
6.4%
21.3%
0.0%
0.0%
5.8%
0.0%
15.4%
3.8%
25.0%
7.7%
32.7%
100.0%
0.0%
0.0%
33.3%
33.3%
33.3%
0.0%
33.3%
0.0%
66.7%
66.7%
100.0%
66.7%
66.7%
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A Review of Contaminant Occurrence in Public Water Systems
Table V.A.3. Summary of the percentage of systems with exceedances (>MCL*) of selected
contaminants, comparing ground-water and surface-water supplied systems, by size of system
(population served categories), for a high-occurrence state.
Contaminant
Population Served
<500
500-3,300
3,301-10,000
10,001-50,000
> 50,000
Surface Water (% > MCL*)
IOCS
Barium
Cadmium
Mercury
SOCs
2,4-D
Atrazine
Benzo[a]pyrene
Carbofuran (Furadan)
Ethylene Dibromide (EDB)
Glyphosate (Roundup)
VOCs
Benzene
Styrene
Tetrachloroethylene
Vinyl Chloride
Xyienes (Total)
0.0%
0.0%
0.0%
0.0%
77.8%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
Ground Water (% > MCL*)
lOCs
Barium
Cadmium
Mercury
SOCs
2,4-D
Atrazine
Benzo(a]pyrene
Carbofuran (Furadan)
Ethylene Dibromide (EDB)
Glyphosate (Roundup)
VOCs
Benzene
Styrene
Tetrachloroethylene
Vinyl Chloride
Xyienes (Total)
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.1%
0.0%
0.4%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
71.1%
0.0%
0.0%
0.0%
0.0%
2.6%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
57.7%
0.0%
0.0%
20.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
18.5%
0.0%
0.0%
10.7%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
2.8%
1.4%
1.9%
0.0%
1.1%
0.0%
0.0% ]
0.9%
0.0%
0.5%
0.0%
0.7%
0.2%
0.0%
4.8%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
2.9%
0.0%
1.0%
0.0%
0.0%
1.9%
0.0%
18.2%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
1.9%
0.0%
0.0%
0.0%
3.8%
0.0%
0.0%
25.0%
0.0%
0.0%
0.0%
22.2%
0.0%
0.0%
9.1%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
33.3%
33.3%
0.0%
33.3%
0.0%
0.0%
0.0%
33.3%
0.0%
0.0%
* %> MCL indicates the proportion of systems with any analytical results exceeding the concentration value of the MCL; it does not necessarily
indicate an MCL violation. An MCL violation occurs when the MCL is exceeded by the average results from four quarterly samples or
confirmation samples as required by the primacy Slate.
D-3
-------
A Review of Contaminant Occurrence in Public Water Systems
Table V.A.4. Summary of the percentage of systems with detections (>MRL) of selected
contaminants, comparing ground-water and surface-water supplied systems, by size of system
(population served categories), for a low-occurrence state.
Contaminant
Population Served
<500
500-3,300
3,301-10,000
10,001-50,000
> 50,000
Surface Water (% > MRL)
lOCs
Barium
Cadmium
Mercury
SOCs
2,4-D
Atrazine
Benzo[a]pyrene
Carbofuran (Furadan)
Ethylene Dibromide (EDB)
Glyphosate (Roundup)
VOCs
Benzene
Styrene
Tetrachloroethylene
Vinyl Chloride
Xylenes (Total)
29.6%
5.6%
11.3%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
4.5%
0.0%
2.3%
Ground Water (% > MRL)
IOCS
Barium
Cadmium
Mercury
SOCs
2,4-D
Atrazine
Benzo[a]pyrene
Carbofuran (Furadan)
Ethylene Dibromide (EDB)
Glyphosate (Roundup)
VOCs
Benzene
Styrene
Tetrachloroethylene
Vinyl Chloride
Xyienes (Total)
29.3%
5.4%
6.7%
0.3%
0.0%
0.0%
0.0%
0.9%
0.0%
0.2%
0.0%
6.5%
0.0%
1.5%
33.3%
1.6%
17.5%
3.3%
0.0%
0.0%
0.0%
0.0%
0.0%
1.6%
0.0%
3.5%
1.6%
3.5%
45.8%
6.7%
9.2%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.8%
0.0%
10.3%
0.0%
3.9%
66.7%
16.7%
16.7%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
5.6%
0.0%
5.6%
0.0%
36.4%
4.5%
9.1%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
4.5%
0.0%
0.0%
0.0%
0.0%
36.4%
4.5%
9.1%
0.0%
0.0%
0.0%
4.8%
4.8%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
64.7%
29.4%
23.5%
0.0%
0.0%
0.0%
0.0%
6.3%
0-0%
5.6%
0.0%
0.0%
0.0%
0.0%
50.0%
0.0%
25.0%
0.0%
0.0%
0.0%
25.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
33.3%
0.0%
33.3%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
33.3%
0.0%
0.0%
D-4
-------
A Review of Contaminant Occurrence in Public Water Systems
Table V.A.5. Summary of the percentage of systems with exceedances (>MCL*) of selected
contaminants, comparing ground-water and surface-water supplied systems, by size of system
(population served categories), for a low-occurrence state.
Contaminant
Population Served
50,000
Surface Water (% > MCL*)
lOCs
Barium
Cadmium
Mercury
SOCs
2,4-D
Atrazine
Benzo[a]pyrene
Carbofuran (Furadan)
Ethylene Dibromide (EDB)
Glyphosate (Roundup)
VOCs
Benzene
Styrene
Tetrachloroethylene
Vinyl Chloride
Xylenes (Total)
Ground Water (% > MCL*)
lOCs
Barium
Cadmium
Mercury
SOCs
2,4-D
Atrazine
Benzo[a]pyrene
Carbofuran (Furadan)
Ethylene Dibromide (EDB)
Giyphosate (Roundup)
VOCs
Benzene
Styrene
Tetrachloroethylene
Vinyl Chloride
Xylenes (Total)
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
2.3%
0.0%
0.0%
0.1%
0.3%
0.1%
0.0%
0.0%
0.0%
0.0%
0.3%
0.0%
0.1%
0.0%
1.8%
0.0%
0.0%
1.6%
0.0%
3.2%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
1.7%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
* % > MCL indicates the proportion of systems with any analytical results exceeding the concentration value of the MCL; it does not necessarily
indicate an MCL violation. An MCL violation occurs when the MCL is exceeded by the average results from four quarterly samples or
confirmation samples as required by the primacy State.
D-5
-------
A Review of Contaminant Occurrence in Public Water Systems
Table V.A.6. Summary of the percentage of systems with detections (>MRL) of selected
contaminants, comparing ground-water and surface-water supplied systems, by size of system
(population served categories), from the national URCIS database.
Contaminant
Population Served
<500
500-3,300
3301-10,000
10,001-50,000
> 50,000
Surface Water (% > MRL)
SOCs
Dibromochloropropane
(DBCP)
Ethylene Dibromide (EDB)
VOCs
Methylene Chloride
Tetrachloroethylene
Toluene
Trichloroethylene
Vinyl Chloride
Xylenes (Total)
1.5%
3.9%
11.1%
1.1%
7.7%
0.5%
1.4%
15.8%
Ground Water (% > MRL)
SOCs
Dibromochloropropane
(DBCP)
Ethylene Dibromide (EDB)
VOCs
Methylene Chloride
Tetrachloroethylene
Toluene
Trichloroethylene
Vinyl Chloride
Xylenes (Total)
1.5%
0.3%
2.7%
2.2%
2.9%
2.1%
0.2%
1.8%
1.7%
0.3%
10.3%
2.0%
6-2%
4.1%
0.6%
7.0%
2.5%
1.1%
3.4%
3.8%
3.6%
4.0%
0.5%
5.0%
1.1%
1.3%
14.5%
1.3%
7.3%
7.2%
1.2%
9.8%
4.8%
3.4%
8.0%
9.6%
8.2%
10.4%
0.8%
7.9%
3.3%
3.4%
14.6%
5.5%
8.2%
12.6%
2.1%
11.8%
12.2%
6.8%
14.0%
23.8%
10.3%
23.3%
2.9%
6.9%
10.7%
10.1%
17.1%
13.8%
13.1%
22.1%
3.1%
17.2%
21.9%
13.3%
24.5%
42.8%
17.3%
39.4%
5.5%
10.2%
D-6
-------
A Review of Contaminant Occurrence in Public Waier Systems
Table V.A.7. Summary of the percentage of systems with exceedances (>MCL*) of selected
contaminants, comparing ground-water and surface-water supplied systems, by size of system
(population served categories), from the national URCIS database.
Contaminant
Population Served
<500
500-3,300
3301-10,000
10,001-50,000
> 50,000
Surface Water (% > MCL*)
SOCs
Dibromochloropropane
(DBCP)
Ethylene Dibromide (EDB)
VOCs
Methylene Chloride
Tetrachloroethylene
Toluene
Trichloroethylene
Vinyl Chloride
Xylenes (Total)
2.5%
0.5%
4.3%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.9%
2.9%
0.4%
0.0%
0.3%
0.3%
0.0%
0.7%
0.7%
4.1%
0.8%
0.0%
0.4%
0.8%
0.0%
0.3%
1.6%
3.9%
1.2%
0.0%
2.0%
1.3%
0.0%
3.4%
5.8%
4.8%
3.7%
0.0%
8.7%
2.1%
0.0%
Ground Water (% > MCL*)
SOCs
Dibromochloropropane
(DBCP)
Ethylene Dibromide (EDB)
VOCs
Methylene Chloride
Tetrachloroethylene
Toluene
Trichloroethylene
Vinyl Chloride
Xylenes (Total)
0.9%
0.2%
0.4%
0.4%
0.0%
0.4%
0.1%
0.0%
1.2%
0.5%
0.7%
1.0%
0.0%
1.0%
0.1%
0.0%
2.6%
2.1%
1.7%
2.9%
0.0%
3.5%
0.1%
0.0%
6.2%
5.6%
2.8%
9.2%
0.0%
8.4%
1.4%
0.0%
8.8%
6.3%
5.4%
23.3%
0.0%
22.4%
3.7%
0.0%
* % > MCL indicates the proportion of systems with any analytical results exceeding the concentration value of the MCL; it does not necessarily
indicate an MCL violation. An MCL violation occurs when the MCL is exceeded by the average results from four quarterly samples or
confirmation samples as required by the primacy State.
D-7
-------
A Review of Contaminant Occurrence in Public Water Systems
Table V.A.8. Summary of the percentage of systems with detections (>MRL) of selected
unregulated contaminants, comparing ground-water and surface-water supplied systems, by size
of system (population served categories), from the national URCIS database.
Contaminant
Population Served
<500
500-3300
3301-10,000
10,001-50,000
> 50,000
Surface Water (% > MRL)
VOCs
(m-) 1,3-Dichlorobenzene
1,1,1 ,2-Tetrachloroethane
1 ,2,3-Trichloropropane
Bromomelhane
Chloromelhane
o-Chlorotoluene
p-ChlorotoIuene
Ground Water (% > MRL)
VOCs
(m-> 1,3-Dichlorobenzene
1,1,1 ,2-Tetrachloroethane
1 ,2,3-Trichloropropane
Bromomethane
Chloromethane
o-Chlorotoluene
p-Chlorotoluene
1.7%
0.4%
0.4%
2.0%
1.7%
0.7%
0.8%
0.2%
0.2%
0.2%
0.2%
2.6%
0.4%
0.0%
0.3%
1.3%
0.3%
0.5%
2.5%
0.5%
0.3%
0-8%
0.8%
0.3%
2.1%
2-4%
1.1%
0.8%
0.2%
0.0%
0.2%
0.7%
1.3%
0.1%
0.1%
0.1%
0.1%
0.1%
0.6%
1.6%
0.1%
0.1%
0.3%
0.2%
0.7%
0.7%
3.2%
0.5%
0.5%
0.7%
1.5%
1.9%
1.8%
3.3%
0.4%
0.9%
2.1%
1.3%
0.7%
3.7%
5.0%
0.0%
0.0%
2.2%
4.0%
4.4%
3.3%
4.9%
4.9%
3.0%
D-8
-------