Pesticides National Synthesis Project
National Water-Quality Assessment
U.S. Geological Survey
INTRODUCTION Final results from the first cycle of NAWQA water-quality data collection during 1992-1996 include analyses of 76 pesticides and 7 selected pesticide degradation products in about 8,200 samples of ground water and surface water in 20 of the nation's major hydrologic basins (NAWQA study units). These data are the most extensive ever collected for such a wide range of pesticides and locations. The 76 herbicides, insecticides, and fungicides targeted in the study account for approximately 75 percent of the total amount (by weight) of pesticides used for agriculture in the U.S., and also a substantial portion of urban and suburban use. In addition, 7 volatile organic pesticides, which are used as fumigants, were analyzed in a subset of about 2000 ground water samples. This statistical summary of national results for ground water and surface water is one of a series of products that will be developed to describe findings from the NAWQA studies. This summary updates and replaces a similar preliminary summary that was first provided on this web page August, 1997 and removed for revision in May of 1998. Final revisions to data resulting from additional data submissions and quality control checking, combined with changes in methods for aggregating data (described below), have resulted in changes (mostly minor) from the preliminary summary. OVERVIEW OF RESULTS Fifty-eight pesticides were detected at least once above 0.01 ug/L in both ground water and surface water. Only 6 of the 83 compounds measured in streams were never detected (2,4,5-T; 3-OH-carbofuran; chloramben, clopyralid, MCPB, and silvex). Pesticides were more frequently present and at higher concentrations in streams compared to ground water. More than 95 percent of all samples collected from streams contained one or more pesticides, compared to less than 50 percent of samples collected from wells. The same herbicides were most commonly found in streams and ground water -- the most commonly detected were atrazine and metolachlor, used primarily on corn and soybeans; prometon, used primarily in non-agricultural applications in urban and suburban areas; and simazine, which is used in both agricultural and non-agricultural settings. Some insecticides were commonly found in streams, but none were found often in ground water. The insecticides detected most frequently in streams were diazinon, chlorpyrifos, and carbaryl, all of which have substantial urban and suburban use. SELECTED HIGHLIGHTS (Yvonne has figures 1-7 all ready for you!) (Adapted from a poster presented at the 9th International Congress of Pesticide Chemistry, August 1998: "Pesticides in streams and ground water of the United States, 1993-95" by Robert J. Gilliom, Jack E. Barbash, Yvonne M. Gobert, Dana W. Kolpin, Steven J. Larson, Naomi Nakagaki, and William G. Wilber) More than 95% of all samples collected from streams and rivers contained at least one pesticide, compared to about 50% for ground water (Figure 1). Most detections in streams were greater than 0.01 mg/L and more than half were greater than 0.05 mg/L. In contrast, more than half the detections in ground water were less than 0.01 mg/L, although most detections greater than 0.01 mg/L were also greater than 0.05 mg/L. Agricultural and urban streams, as well as major rivers, had relatively similar high frequencies of detection. Detection frequencies in ground water were highest in shallow ground water in agricultural areas, somewhat lower in shallow ground water in urban areas, and lowest in major aquifers. The major aquifers are generally deeper, have variable land-use influences, and were sampled using existing production wells. The 21 most commonly detected pesticides exceeded 0.05 mg/L in more than 10 percent of stream samples or in more than 1 percent of ground water samples within at least one of the land-use categories (Figure 2). The most freqently detected pesticides in agricultural areas were the major herbicides, atrazine and its degradation product deethylatrazine (DEA), metolachlor, cyanazine, and alachlor, which herbicides rank 1, 2, 4, and 5 in national herbicide use for agriculture. These most heavily used herbicides also account for most of the detections in larger rivers and major aquifers and many detections in urban streams and shallow ground water. The herbicides that were generally found most often in urban areas are simazine, prometon, 2,4-D, diuron, and tebuthiuron, with simazine and prometon accounting for most detections in streams and shallow ground water. 2,4-D and prometon rank 1 and 14 among herbicides in frequency of home and garden use, and 2,4-D, simazine, and diuron rank 3, 18, and 23, respectively in national herbicide use for agriculture. Prometon and tebuthiuron have no reported agricultural use. Insecticides were much more frequently detected in urban streams than in agricultural streams and were seldom detected in ground water in any setting. Most detections were accounted for by diazinon, carbaryl, malathion, and chlorpyrifos, which nationally rank 1, 8, 13, and 4 among insecticides in frequency of home and garden use. Low-level mixtures are the most common form of pesticide exposure for stream ecosystems and water usersÑmost samples with a detectable pesticide contained mixtures of two or more detectable pesticides (Figure 3). More than 50 percent of all stream samples contained 5 or more pesticides and about 25 percent of ground water samples had 2 or more pesticides. In accordance with use patterns, the composition of the most common mixtures differs between urban and agricultural areas and among agricultural areas with different crops and pests. For example, simazine and prometon were present in the most commonly occurring mixtures of 2 or more compounds in urban areas, whereas atrazine, DEA, and metolachlor were the most common compounds in mixtures found in agricultural areas. A distinctive feature of urban streams was the common occurrence of mixtures with both herbicides and insecticides. More than 10 percent of urban stream samples contained a mixture of at least four herbicides plus diazinon and chlorpyrifos. Drinking-water standards for individual pesticides were rarely exceeded in streams or ground water, but aquatic-life criteria were commonly exceeded in some streams. Most of the major aquifers and about half of the shallow ground-water zones sampled are sources of drinking water. Most concentrations are substantially below U. S. Environmental Protection Agency (EPA) drinking-water standards, which were exceeded in less than 1 percent of the wells sampled. In streams, peak levels of several herbicides frequently occurred above EPA drinking-water standards in some agricultural areas, but annual average concentrations, which are used for regulation, rarely exceeded standards. For drinking water, NAWQA results are generally good news regarding individual pesticides and current regulations. This conclusion is tempered, however, by the fact that criteria are not established for many pesticides, mixtures and degradation products are not considered, and a limited range of potential effects have been assessed. Concentrations in streams more frequently exceeded criteria for the protection of aquatic life. Aquatic-life criteria established by EPA, Canada, or the International Joint Commission for the Great Lakes were exceeded by a least one compound in one or more samples for about two thirds of the streams sampledÑmost commonly by the herbicides atrazine or cyanazine, or the insecticides azinphos-methyl, chlorpyrifos, diazinon, or malathion. Many of the exceedances were only one or two samples, but sustained periods of time with exceedances were common for atrazine and diazinon at some sites. For aquatic life, NAWQA results indicate a relatively high potential for effects in some streams, with the additional concerns (as for drinking water) that criteria have not been established for many pesticides, mixtures and degradation products are not considered, and a limited range of potential effects have been assessed. The geographic distribution of pesticide concentrations generally follows regional patterns in agricultural use and the influence of urban areas(Figures 4-7). The geographic distribution of the concentrations of pesticides in streams was evaluated by determining the annual 75th percentile of monthly median concentrations of total herbicides and total insecticides (sum of all compounds of each type) for each site, expressing the values for each site as multiples of the national median, and ranking by national quartiles. For ground water, the overall detection frequency of any pesticide of each type was determined for each study, values were expressed as multiples of the national median, and each study was ranked by national quartiles. Blue (lowest) and green symbols on the maps indicate where values were less than the national median and orange and red (highest) symbols indicate where values were greater than the national median. Results for pesticides in streams show that herbicides and insecticides in agricultural streams, and in most large streams and rivers in agricultural regions, were generally highest in areas of the nation with the greatest agricultural use (Figures 4 and 5). Herbicide concentrations were generally greatest in the streams of the central U.S. where use is most extensive. Urban streams had the highest insecticide concentrations, with 7 of 11 having total insecticide concentrations in the upper 25 percent, but some agricultural streams in irrigated agricultural areas of the western U.S. also had high levels. Results for pesticides in ground water show that herbicides were highest in shallow ground water within agricultural areas and lowest in major aquifers, but the locations of areas with the highest detection frequencies do not follow use patterns as clearly as for streams (Figure 7). Insecticides were seldom detected in ground water and patterns are unclear (Figure 6). Pesticides in ground water, compared to streams, are more variably affected by local hydrogeologic factors, such as soil conditions and the depth and type of aquifer. SAMPLING DESIGN AND CONSIDERATIONS FOR DATA INTERPRETATION NAWQA studies are based on a complex sampling design that targets specific land use and hydrologic conditions in addition to assessing the most important aquifers and streams in each area studied. The studies are not designed to produce a statistically representative analysis of national water-quality conditions, especially with results only from the first 20 study units. The NAWQA sampling design is described by Gilliom and others (1995) and the relation of the 20 study units to the entire U.S. is described by Gilliom and others (1997). For both streams and ground water, a major approach of the sampling design is to target specific watersheds and shallow ground water areas that are influenced primarily by a single dominant land use(agricultural or urban) that is important in the particular area. This aspect of the sampling design facilitates summarizing results by agricultural and urban land use settings for both streams and ground water. However, the results from this design require careful interpretation. In particular, the NAWQA design does not result in an unbiased representation of all streams or shallow ground water in agricultural settings. For agricultural land use, the focus was limited to the most important agricultural settings within the 20 study areas. Thus, some agricultural activities and related pesticide use that may be very important in a particular part of the nation may not be included. For example, the first 20 study areas did not include intensive rice growing areas. On the other hand, a particular pesticide may be important in one or two of the 20 study units, but not in the others, and the averaged results may be misleading in this regard. Another possibility is that use of a particular pesticide is much greater than average in the watersheds and ground-water areas studied, leading to an overestimate of occurrence and concetrations relative to other areas. Similar biases are possible for urban areas as well, but the dominant pesticides used are probably more similar among urban areas than they are among agricultural areas with different crops. For both streams and ground water, statistical summaries for agricultural and urban land uses and for major streams and aquifers were prepared from a carefully selected subset of the complete NAWQA data set in order to minimize biases due to different temporal sampling strategies. The criteria for data selection are described below for each situation. These summaries by NAWQA study component provide a balanced summary of results. In addition, a summary of all data collected, including all types of land use settings and many different types of hydrologic conditions, is included for the purpose of cross-checking with the original data that can be downloaded. Therefore, the summaries of results presented below must be used wih caution. The summaries by NAWQA study component are designed to give a broad and averaged perspective on national results with the understanding that more detailed analysis, which fully considers the sampling design and the variable nature of pesticide use patterns and hydrologic conditions, is underway.
The summary data shown in Table 1 provide a basis for comparison and cross-checking with the complete stream-water data set available for downloading. Table 1 SHOULD NOT be presumed to be a statistically representative summary of the NAWQA pesticide results. The summaries in Tables 2-4, although also not a statistically representative sampling of the nation, are more representative and comparable assessments of pesticide levels in streams because both the sites and samples were carefully selected to control or minimize bias.
Tables 2-4 summarize the results of NAWQA sampling for pesticides in streams draining relatively basins that represent specific agricultural and urban land uses (indicator sites) and streams draining large basins with mixed land uses (integrator sites). The summaries in Tables 2-4 are based on samples collected during a one-year period at 65 sites located on streams within the first 20 NAWQA study units. The sites used for these summaries are listed in Table 5, along with the number of samples collected at each site and the time period used for summarizing results. Table 2 summarizes results from 40 streams with primarily agricultural basins. These agricultural indicator sites have relatively small basins (27 to 6000 sq km, with most less than 1000 sq km) and include a variety of different crop types and agricultural practices. Table 3 summarizes results from 11 streams with primarily urban basins. These urban indicator sites have small basins (25 to 108 sq km) in which the primary uses of pesticides are non-agricultural. Table 4 summarizes results from 14 integrator sites on large streams and rivers that drain relatively large basins (1800 to 92000 sq km) with heterogeneous land use, diverse soil types and topography, and usually a variety of pesticide uses.
Samples were collected throughout the year at most of the 65 sites included in Tables 2-4. Not all samples collected during the year at each site were used in the calculation of the summary statistics, however. Samples collected as part of a fixed-frequency sampling schedule were included, along with a much smaller number of samples collected during periods of extreme high or low flow. Samples collected over a storm hydrograph, or as part of a study of diurnal variability, were excluded in order to avoid bias resulting from repeated sampling during extreme conditions. The sampling frequency at most sites was higher during periods of the year when pesticide concentrations were expected to be elevated, so that the detection frequencies and concentration data shown may be somewhat higher than would be obtained from samples evenly distributed throughout the year. At most sites, 1 to 2 samples were collected each month during periods when pesticide transport in the streams was expected to be low. Sampling frequency increased to 1 to 3 samples per week during periods when elevated levels of pesticides were expected in the streams.
The concentrations observed for each pesticide compound are summarized in all four tables using concentration percentiles. The maximum concentration detected for each of the compounds is also shown. As an example, atrazine concentrations at the 40 agricultural sites included in Table 2 were below the detection limit in 10 percent of samples, less than or equal to 0.021 ug/L in 50 percent of samples, less or equal to than 0.57 ug/L in 90 percent of samples, and less than or equal to 1.9 ug/L in 95 percent of samples. The percentiles may also be interpreted as the percentage of samples above a given concentration. For example, atrazine concentrations exceeded 1.9 ug/L in 5 percent of the samples collected at the agricultural sites.
All compounds denoted with (E) have more variable analytical performance than other compounds and usually much lower recoveries. Individual maximum values with an E-code have greater uncertainty because the values were beyond the calibration range. ( http://water.wr.usgs.gov/pnsp/anstrat/)
DETECTION FREQUENCY (%) CONCENTRATION PERCENTILES (ug/L)
COMPOUND SAMPLES >=.01 ug/L >=.05 ug/L 10th 50th 90th 95th max
2,6-Diethylaniline 5196 0.19 0.00 < MDL < MDL < MDL < MDL .031
Acetochlor 1987 9.43 4.39 < MDL < MDL 0.008 0.039 3.8
Alachlor 5198 22.62 9.91 < MDL < MDL 0.049 0.19 25E
Atrazine 5196 66.01 40.98 < MDL 0.026 0.70 2.0 120E
Atrazine, deethyl (E) 5197 38.06 17.81 < MDL 0.096 0.096 0.17 1.1E
Azinphos-methyl (E) 5136 2.65 1.42 < MDL < MDL < MDL < MDL 1.0E
Benfluralin 5196 0.75 0.04 < MDL < MDL < MDL < MDL 0.097
Butylate 5196 2.83 0.85 < MDL < MDL < MDL 0.003 1.4
Carbaryl (E) 5198 15.44 6.03 < MDL < MDL .012 0.064 5.5E
Carbofuran (E) 5198 6.93 3.08 < MDL < MDL < MDL 0.022 9.7E
Chlorpyrifos 5196 13.69 2.25 < MDL < MDL 0.013 0.026 0.40
Cyanazine 5198 28.82 14.88 < MDL < MDL 0.11 0.43 160E
DCPA 5196 7.12 2.35 < MDL < MDL 0.006 0.015 100E
DDE, p,p' 5196 1.19 0.02 < MDL < MDL < MDL < MDL 0.062
Diazinon 5158 24.95 10.32 < MDL < MDL 0.051 0.13 3.8
Dieldrin 5196 2.39 0.04 < MDL < MDL < MDL < MDL 0.19
Disulfoton 5196 0.12 0.04 < MDL < MDL < MDL < MDL 0.06
EPTC 5195 11.17 4.01 < MDL < MDL 0.012 0.038 40E
Ethalfluralin 5196 1.91 0.52 < MDL < MDL < MDL < MDL 0.36
Ethoprop 5198 1.04 0.31 < MDL < MDL < MDL < MDL 2.0
Fonofos 5196 3.02 0.67 < MDL < MDL < MDL 0.005 1.2
HCH, alpha 5196 0.44 0.08 < MDL < MDL < MDL < MDL 0.21
HCH, gamma 5196 1.79 0.54 < MDL < MDL < MDL < MDL 0.13
Linuron 5196 2.39 0.94 < MDL < MDL < MDL < MDL 1.4
Malathion 5196 5.51 1.81 < MDL < MDL < MDL 0.011 4.3E
Methyl parathion 5196 0.42 0.08 < MDL < MDL < MDL < MDL 0.30
Metolachlor 5191 51.62 28.43 < MDL 0.011 0.33 0.91 70E
Metribuzin 5196 9.94 2.79 < MDL < MDL 0.009 0.026 0.53
Molinate 5196 2.10 1.08 < MDL < MDL < MDL < MDL 200E
Napropamide 5198 4.22 0.94 < MDL < MDL < MDL 0.007 1.67
Parathion 5196 0.13 0.04 < MDL < MDL < MDL < MDL 0.14
Pebulate 5196 0.98 0.35 < MDL < MDL < MDL < MDL 0.80
Pendimethalin 5196 7.84 2.50 < MDL < MDL 0.006 0.021 3.2
Permethrin, cis 5196 0.12 0.00 < MDL < MDL < MDL < MDL 0.028
Phorate 5196 0.21 0.06 < MDL < MDL < MDL < MDL 0.60
Prometon 5198 40.08 13.65 < MDL < MDL 0.066 0.11 4.2E
Pronamide 5198 1.06 0.19 < MDL < MDL < MDL < MDL 0.43
Propachlor 5198 1.23 0.50 < MDL < MDL < MDL < MDL 0.68
Propanil 5198 0.46 0.13 < MDL < MDL < MDL < MDL 0.72
Propargite 5196 2.62 1.62 < MDL < MDL < MDL < MDL 20E
Simazine 5198 53.86 25.35 < MDL 0.012 0.17 0.38 20E
Tebuthiuron 5198 16.75 2.79 < MDL < MDL 0.018 0.032 6.4E
Terbacil (E) 5127 3.02 1.36 < MDL < MDL < MDL < MDL 0.99E
Terbufos 5196 0.33 0.13 < MDL < MDL < MDL < MDL 0.56
Thiobencarb 5196 0.71 0.17 < MDL < MDL < MDL < MDL 0.93
Triallate 5196 2.08 0.58 < MDL < MDL < MDL < MDL 0.65
Trifluralin 5196 5.76 0.83 < MDL < MDL 0.01 0.011 0.51
2,4,5-T 3409 -- ND < MDL < MDL < MDL < MDL < MDL
2,4-D 3400 -- 10.36 < MDL < MDL 0.050 0.21 15E
2,4-DB 3411 -- 0.12 < MDL < MDL < MDL < MDL 1.1
3-OH-carbofuran 3413 -- ND < MDL < MDL < MDL < MDL < MDL
Acifluorfen 3408 -- 0.70 < MDL < MDL < MDL < MDL 2.2
Aldicarb (E) 3416 -- 0.12 < MDL < MDL < MDL < MDL 0.51E
Aldicarb sulfone (E) 3405 -- 0.03 < MDL < MDL < MDL < MDL 0.07E
Aldicarb sulfoxide (E) 3404 -- 0.09 < MDL < MDL < MDL < MDL 0.98E
Bentazon 3399 -- 4.09 < MDL < MDL < MDL 0.001 8.6E
Bromacil 3419 -- 1.05 < MDL < MDL < MDL < MDL 5E
Bromoxynil 3400 -- 0.62 < MDL < MDL < MDL < MDL 6.1E
Chloramben 3418 -- ND < MDL < MDL < MDL < MDL < MDL
Chlorothalonil (E) 3405 -- 0.21 < MDL < MDL < MDL < MDL 0.68E
Clopyralid 3395 -- ND < MDL < MDL < MDL < MDL 0.01
Dacthal mono-acid 3400 -- 0.26 < MDL < MDL < MDL < MDL 1.2
Dicamba 3401 -- 0.50 < MDL < MDL < MDL < MDL 0.38
Dichlobenil (E) 3418 -- 0.15 < MDL < MDL < MDL < MDL 0.32E
Dichlorprop 3410 -- 0.47 < MDL < MDL < MDL < MDL 0.34
Dinoseb 3410 -- 0.26 < MDL < MDL < MDL < MDL 1.0
Diuron 3418 -- 9.19 < MDL < MDL 0.030 0.22 14E
DNOC (E) 3400 -- 0.24 < MDL < MDL < MDL < MDL 0.54E
Fenuron 3413 -- 0.09 < MDL < MDL < MDL < MDL 0.10
Fluometuron 3419 -- 2.98 < MDL < MDL < MDL < MDL 8.6E
MCPA 3401 -- 1.74 < MDL < MDL < MDL < MDL 1.3
MCPB 3411 -- ND < MDL < MDL < MDL < MDL 0.05
Methiocarb 3419 -- 0.06 < MDL < MDL < MDL < MDL 0.23
Methomyl 3404 -- 0.44 < MDL < MDL < MDL < MDL 3.0
Neburon 3418 -- 0.00 < MDL < MDL < MDL < MDL 0.02
Norflurazon 3418 -- 0.73 < MDL < MDL < MDL < MDL 1.4
Oryzalin 3418 -- 0.97 < MDL < MDL < MDL < MDL 1.9
Oxamyl 3403 -- 0.03 < MDL < MDL < MDL < MDL 0.07
Picloram 3384 -- 0.12 < MDL < MDL < MDL < MDL 2.7
Propham 3418 -- 0.06 < MDL < MDL < MDL < MDL 0.07
Propoxur 3269 -- 0.06 < MDL < MDL < MDL < MDL 0.26
Silvex 3410 -- ND < MDL < MDL < MDL < MDL < MDL
Triclopyr 3410 -- 0.85 < MDL < MDL < MDL < MDL 16E
DETECTION FREQUENCY (%) CONCENTRATION PERCENTILES (ug/L)
COMPOUND SAMPLES >=.01 ug/L >=.05 ug/L 10th 50th 90th 95th max
2,6-Diethylaniline 1000 0.20 ND < MDL < MDL < MDL < MDL 0.018
Acetochlor* 56 ND ND < MDL < MDL < MDL < MDL < MDL
Alachlor 1001 27.37 11.49 < MDL < MDL 0.065 0.22 5.4
Atrazine 1000 66.20 38.30 < MDL 0.021 0.57 1.9 120E
Atrazine, deethyl (E) 1000 35.90 15.40 < MDL 0.003 0.074 0.14 0.863E
Azinphos-methyl (E) 998 2.61 1.80 < MDL < MDL < MDL < MDL 0.54E
Benfluralin 1000 ND ND < MDL < MDL < MDL < MDL 0.007
Butylate 1000 4.70 2.60 < MDL < MDL < MDL 0.006 1.4
Carbaryl (E) 1001 6.99 2.10 < MDL < MDL 0.003 0.016 1.5E
Carbofuran (E) 1001 10.79 5.49 < MDL < MDL 0.013 0.059 7E
Chlorpyrifos 1000 10.00 2.10 < MDL < MDL 0.009 0.022 0.22
Cyanazine 1001 25.17 13.19 < MDL < MDL 0.095 0.38 160E
DCPA 1000 9.50 4.10 < MDL < MDL 0.008 0.033 40E
DDE, p,p' 1000 0.60 0.10 < MDL < MDL < MDL 0.002 0.062
Diazinon 1000 11.20 3.3 < MDL < MDL 0.012 0.027 1.2
Dieldrin 1000 3.90 ND < MDL < MDL < MDL 0.007 0.027
Disulfoton 1000 0.20 ND < MDL < MDL < MDL < MDL 0.035
EPTC 999 14.41 4.70 < MDL < MDL 0.018 0.047 7.3E
Ethalfluralin 1000 3.30 0.70 < MDL < MDL < MDL < MDL 0.13
Ethoprop 1001 2.00 0.50 < MDL < MDL < MDL < MDL 0.46
Fonofos 1000 3.50 0.80 < MDL < MDL < MDL 0.005 1.2
HCH, alpha 1000 0.10 ND < MDL < MDL < MDL < MDL 0.011
HCH, gamma 1000 1.20 0.20 < MDL < MDL < MDL < MDL 0.13
Linuron 1000 2.70 1.70 < MDL < MDL < MDL < MDL 1.4
Malathion 1000 3.70 0.50 < MDL < MDL < MDL 0.006 0.39
Methyl parathion 1000 0.90 0.20 < MDL < MDL < MDL < MDL 0.23
Metolachlor 1001 53.05 26.87 < MDL 0.011 0.30 0.87 23E
Metribuzin 1000 8.20 1.50 < MDL < MDL 0.008 0.016 0.33
Molinate 1000 4.60 3.00 < MDL < MDL < MDL < MDL 200E
Napropamide 1001 5.69 1.50 < MDL < MDL < MDL 0.012 0.77
Parathion 1000 0.20 0.20 < MDL < MDL < MDL < MDL 0.14
Pebulate 1000 1.20 0.60 < MDL < MDL < MDL < MDL 0.24
Pendimethalin 1000 6.90 1.70 < MDL < MDL 0.006 0.012 0.19
Permethrin, cis 1000 0.30 ND < MDL < MDL < MDL < MDL 0.019
Phorate 1000 0.10 0.10 < MDL < MDL < MDL < MDL 0.60
Prometon 1001 26.17 8.69 < MDL < MDL 0.038 0.079 1.4
Pronamide 1001 1.20 0.10 < MDL < MDL < MDL < MDL 0.20
Propachlor 1001 0.60 0.10 < MDL < MDL < MDL < MDL 0.11
Propanil 1001 0.80 0.20 < MDL < MDL < MDL < MDL 0.72
Propargite 1000 3.40 2.40 < MDL < MDL < MDL 0.004 20E
Simazine 1001 44.76 16.98 < MDL 0.007 0.10 0.27 5.76E
Tebuthiuron 1001 7.59 0.80 < MDL < MDL 0.008 0.015 0.17
Terbacil (E) 992 4.44 1.71 < MDL < MDL < MDL < MDL 0.54E
Terbufos 1000 0.20 0.10 < MDL < MDL < MDL < MDL 0.56
Thiobencarb 1000 2.40 0.70 < MDL < MDL < MDL < MDL 0.93
Triallate 1000 3.50 1.20 < MDL < MDL < MDL 0.006 0.65
Trifluralin 1000 6.90 0.80 < MDL < MDL 0.007 0.012 0.11
2,4,5-T 938 -- ND < MDL < MDL < MDL < MDL < MDL
2,4-D 938 -- 10.66 < MDL < MDL 0.060 0.22 15E
2,4-DB 939 -- 0.21 < MDL < MDL < MDL < MDL 0.13E
3-OH-carbofuran 942 -- ND < MDL < MDL < MDL < MDL < MDL
Acifluorfen 938 -- 0.43 < MDL < MDL < MDL < MDL 1.1
Aldicarb (E) 942 -- 0.32 < MDL < MDL < MDL < MDL 0.51E
Aldicarb sulfone (E) 942 -- ND < MDL < MDL < MDL < MDL < MDL
Aldicarb sulfoxide (E) 942 -- 0.11 < MDL < MDL < MDL < MDL 0.29E
Bentazon 939 -- 3.94 < MDL < MDL < MDL < MDL 8.6E
Bromacil 943 -- 0.53 < MDL < MDL < MDL < MDL 1.9
Bromoxynil 938 -- 0.53 < MDL < MDL < MDL < MDL 0.77
Chloramben 942 -- ND < MDL < MDL < MDL < MDL < MDL
Chlorothalonil (E) 934 -- ND < MDL < MDL < MDL < MDL < MDL
Clopyralid 938 -- ND < MDL < MDL < MDL < MDL < MDL
Dacthal mono-acid 938 -- 0.21 < MDL < MDL < MDL < MDL 0.43
Dicamba 939 -- 0.53 < MDL < MDL < MDL < MDL 0.38
Dichlobenil (E) 942 -- ND < MDL < MDL < MDL < MDL 0.01E
Dichlorprop 938 -- 0.32 < MDL < MDL < MDL < MDL 0.26
Dinoseb 938 -- 0.11 < MDL < MDL < MDL < MDL 1.0
Diuron 942 -- 7.75 < MDL < MDL < MDL 0.23 14E
DNOC (E) 938 -- ND < MDL < MDL < MDL < MDL < MDL
Fenuron 942 -- 0.11 < MDL < MDL < MDL < MDL 0.10
Fluometuron 943 -- 2.65 < MDL < MDL < MDL < MDL 6.5E
MCPA 939 -- 1.49 < MDL < MDL < MDL < MDL 0.92
MCPB 939 -- ND < MDL < MDL < MDL < MDL < MDL
Methiocarb 943 -- 0.11 < MDL < MDL < MDL < MDL 0.10
Methomyl 942 -- 0.85 < MDL < MDL < MDL < MDL 1.0
Neburon 942 -- ND < MDL < MDL < MDL < MDL < MDL
Norflurazon 942 -- 0.53 < MDL < MDL < MDL < MDL 0.44
Oryzalin 942 -- 0.74 < MDL < MDL < MDL < MDL 1.8
Oxamyl 943 -- ND < MDL < MDL < MDL < MDL < MDL
Picloram 938 -- ND < MDL < MDL < MDL < MDL < MDL
Propham 942 -- 0.11 < MDL < MDL < MDL < MDL 0.06
Propoxur 927 -- 0.11 < MDL < MDL < MDL < MDL 0.11
Silvex 938 -- ND < MDL < MDL < MDL < MDL < MDL
Triclopyr 938 -- 0.96 < MDL < MDL < MDL < MDL 16E
* Acetochlor was not used prior to 1994, and was not targeted at most sites during the sampling periods used for table 2. See Table 1 for more complete results for acetochlor.
DETECTION FREQUENCY (%) CONCENTRATION PERCENTILES (ug/L)
COMPOUND SAMPLES >=.01 ug/L >=.05 ug/L 10th 50th 90th 95th max
2,6-Diethylaniline 327 ND ND < MDL < MDL < MDL < MDL 0.006
Acetochlor* 24 ND ND < MDL < MDL < MDL < MDL < MDL
Alachlor 327 8.87 3.67 < MDL < MDL 0.008 0.019 3.8
Atrazine 327 71.56 34.86 < MDL 0.023 0.18 0.45 14
Atrazine, deethyl (E) 327 21.41 11.62 < MDL 0.002 0.053 0.074 0.28E
Azinphos-methyl (E) 324 0.93 0.62 < MDL < MDL < MDL < MDL 0.17E
Benfluralin 327 1.22 ND < MDL < MDL < MDL < MDL 0.011
Butylate 327 0.61 ND < MDL < MDL < MDL < MDL 0.017
Carbaryl (E) 327 38.84 20.80 < MDL < MDL 0.15 0.32 3.2E
Carbofuran (E) 327 2.75 0.31 < MDL < MDL < MDL < MDL 0.062E
Chlorpyrifos 327 25.99 2.45 < MDL < MDL 0.021 0.034 0.30
Cyanazine 327 6.42 1.22 < MDL < MDL < MDL 0.014 0.49
DCPA 327 5.81 ND < MDL < MDL 0.004 0.010 0.045
DDE, p,p' 327 ND ND < MDL < MDL < MDL < MDL 0.007
Diazinon 326 69.94 30.98 < MDL 0.025 0.25 .43 1.9
Dieldrin 327 1.83 ND < MDL < MDL < MDL < MDL 0.016
Disulfoton 327 0.31 ND < MDL < MDL < MDL < MDL 0.018
EPTC 327 0.61 ND < MDL < MDL < MDL < MDL 0.037
Ethalfluralin 327 ND ND < MDL < MDL < MDL < MDL < MDL
Ethoprop 327 0.61 0.31 < MDL < MDL < MDL < MDL 0.052
Fonofos 327 1.22 0.31 < MDL < MDL < MDL < MDL 0.084
HCH, alpha 327 ND ND < MDL < MDL < MDL < MDL < MDL
HCH, gamma 327 0.61 ND < MDL < MDL < MDL < MDL 0.048
Linuron 327 1.22 0.31 < MDL < MDL < MDL < MDL 0.25
Malathion 327 17.13 7.03 < MDL < MDL 0.024 0.063 0.67
Methyl parathion 327 0.31 ND < MDL < MDL < MDL < MDL 0.031
Metolachlor 326 39.26 9.51 < MDL 0.004 0.048 0.095 1.8
Metribuzin 327 5.50 1.53 < MDL < MDL < MDL 0.011 0.10
Molinate 327 0.61 ND < MDL < MDL < MDL < MDL 0.016
Napropamide 327 1.22 ND < MDL < MDL < MDL < MDL 0.021
Parathion 327 0.31 ND < MDL < MDL < MDL < MDL 0.014
Pebulate 327 ND ND < MDL < MDL < MDL < MDL < MDL
Pendimethalin 327 13.76 3.06 < MDL < MDL 0.014 0.035 0.32
Permethrin, cis 327 ND ND < MDL < MDL < MDL < MDL < MDL
Phorate 327 ND ND < MDL < MDL < MDL < MDL < MDL
Prometon 327 79.82 36.09 < MDL 0.031 0.16 0.20 4.2E
Pronamide 327 0.31 ND < MDL < MDL < MDL < MDL 0.021
Propachlor 327 ND ND < MDL < MDL < MDL < MDL 0.008
Propanil 327 1.83 ND < MDL < MDL < MDL < MDL 0.022
Propargite 327 0.31 ND < MDL < MDL < MDL < MDL 0.015
Simazine 327 80.73 40.67 < MDL 0.039 0.29 0.67 8.2E
Tebuthiuron 327 25.38 3.36 < MDL < MDL 0.024 0.037 0.16
Terbacil (E) 324 1.23 ND < MDL < MDL < MDL < MDL 0.048E
Terbufos 327 ND ND < MDL < MDL < MDL < MDL < MDL
Thiobencarb 327 ND ND < MDL < MDL < MDL < MDL 0.009
Triallate 327 0.31 ND < MDL < MDL < MDL < MDL 0.036
Trifluralin 327 0.61 ND < MDL < MDL < MDL 0.004 0.011
2,4,5-T 311 -- ND < MDL < MDL < MDL < MDL < MDL
2,4-D 311 -- 12.54 < MDL < MDL 0.080 0.32 1.4
2,4-DB 311 -- 0.32 < MDL < MDL < MDL < MDL 1.39
3-OH-carbofuran 315 -- ND < MDL < MDL < MDL < MDL < MDL
Acifluorfen 311 -- ND < MDL < MDL < MDL < MDL < MDL
Aldicarb (E) 315 -- ND < MDL < MDL < MDL < MDL < MDL
Aldicarb sulfone (E) 315 -- ND < MDL < MDL < MDL < MDL < MDL
Aldicarb sulfoxide (E) 315 -- ND < MDL < MDL < MDL < MDL < MDL
Bentazon 311 -- 1.29 < MDL < MDL < MDL < MDL 0.50
Bromacil 315 -- 0.63 < MDL < MDL < MDL < MDL 4.0
Bromoxynil 311 -- ND < MDL < MDL < MDL < MDL < MDL
Chloramben 315 -- ND < MDL < MDL < MDL < MDL < MDL
Chlorothalonil (E) 312 -- 0.32 < MDL < MDL < MDL < MDL 0.08E
Clopyralid 311 -- ND < MDL < MDL < MDL < MDL < MDL
Dacthal mono-acid 311 -- ND < MDL < MDL < MDL < MDL < MDL
Dicamba 311 -- 0.32 < MDL < MDL < MDL < MDL 0.16
Dichlobenil (E) 315 -- 0.95 < MDL < MDL < MDL < MDL 0.30E
Dichlorprop 311 -- 0.96 < MDL < MDL < MDL < MDL 0.32
Dinoseb 311 -- ND < MDL < MDL < MDL < MDL < MDL
Diuron 315 -- 11.43 < MDL < MDL 0.066 0.28 8.4E
DNOC (E) 311 -- 0.32 < MDL < MDL < MDL < MDL 0.32E
Fenuron 315 -- ND < MDL < MDL < MDL < MDL < MDL
Fluometuron 315 -- ND < MDL < MDL < MDL < MDL < MDL
MCPA 311 -- 4.82 < MDL < MDL < MDL < MDL 1.3
MCPB 311 -- ND < MDL < MDL < MDL < MDL < MDL
Methiocarb 315 -- ND < MDL < MDL < MDL < MDL < MDL
Methomyl 315 -- 0.32 < MDL < MDL < MDL < MDL 0.14
Neburon 315 -- ND < MDL < MDL < MDL < MDL 0.020
Norflurazon 315 -- ND < MDL < MDL < MDL < MDL 0.040
Oryzalin 315 -- 2.86 < MDL < MDL < MDL < MDL 1.9
Oxamyl 315 -- ND < MDL < MDL < MDL < MDL < MDL
Picloram 311 -- ND < MDL < MDL < MDL < MDL < MDL
Propham 315 -- 0.32 < MDL < MDL < MDL < MDL 0.070
Propoxur 305 -- 0.33 < MDL < MDL < MDL < MDL 0.26
Silvex 311 -- ND < MDL < MDL < MDL < MDL < MDL
Triclopyr 311 -- 2.25 < MDL < MDL < MDL < MDL 0.34
* Acetochlor was not used prior to 1994, and was not targeted at most sites during the sampling periods used for table 3. See Table 1 for more complete results for acetochlor.
DETECTION FREQUENCY (%) CONCENTRATION PERCENTILES (ug/L)
COMPOUND SAMPLES >=.01 ug/L >=.05 ug/L 10th 50th 90th 95th max
2,6-Diethylaniline 245 ND ND < MDL < MDL < MDL < MDL 0.008
Acetochlor* 51 9.80 1.96 < MDL < MDL < MDL 0.036 0.078
Alachlor 246 26.02 10.16 < MDL < MDL 0.050 0.17 2.1
Atrazine 246 80.08 46.34 < MDL 0.042 0.66 1.5 13
Atrazine, deethyl (E) 246 41.06 12.20 < MDL 0.005 0.055 0.10 0.47E
Azinphos-methyl (E) 245 1.22 0.41 < MDL < MDL < MDL < MDL 0.079E
Benfluralin 245 ND ND < MDL < MDL < MDL < MDL 0.009
Butylate 245 2.45 ND < MDL < MDL < MDL 0.004 0.042
Carbaryl (E) 246 16.67 6.50 < MDL < MDL 0.019 0.089 5.2E
Carbofuran (E) 246 7.72 2.85 < MDL < MDL < MDL 0.025 0.18E
Chlorpyrifos 245 10.20 1.22 < MDL < MDL 0.010 0.019 0.13
Cyanazine 246 42.28 21.95 < MDL < MDL 0.21 0.57 5.1
DCPA 245 5.71 0.41 < MDL < MDL 0.004 0.01 0.10
DDE, p,p' 245 ND ND < MDL < MDL < MDL < MDL 0.010
Diazinon 245 25.71 8.16 < MDL < MDL 0.035 0.073 0.40
Dieldrin 245 1.63 ND < MDL < MDL < MDL < MDL 0.015
Disulfoton 245 ND ND < MDL < MDL < MDL < MDL < MDL
EPTC 245 13.06 2.86 < MDL < MDL 0.013 0.025 0.55
Ethalfluralin 245 0.41 ND < MDL < MDL < MDL < MDL 0.017
Ethoprop 246 1.22 ND < MDL < MDL < MDL < MDL 0.023
Fonofos 245 ND ND < MDL < MDL 0.001 0.005 0.010
HCH, alpha 245 ND ND < MDL < MDL < MDL < MDL 0.002
HCH, gamma 245 1.63 ND < MDL < MDL < MDL < MDL 0.020
Linuron 245 1.63 ND < MDL < MDL < MDL < MDL 0.045
Malathion 245 6.12 1.22 < MDL < MDL < MDL 0.013 0.089
Methyl parathion 245 0.41 ND < MDL < MDL < MDL < MDL 0.028
Metolachlor 246 59.76 28.86 < MDL 0.016 0.35 0.76 4.3
Metribuzin 245 9.39 2.04 < MDL < MDL 0.008 0.02 0.13
Molinate 245 1.22 0.41 < MDL < MDL < MDL < MDL 0.16
Napropamide 246 3.25 0.41 < MDL < MDL < MDL < MDL 0.068
Parathion 245 ND ND < MDL < MDL < MDL < MDL < MDL
Pebulate 245 2.45 ND < MDL < MDL < MDL < MDL 0.023
Pendimethalin 245 2.86 ND < MDL < MDL < MDL 0.008 0.028
Permethrin, cis 245 0.41 ND < MDL < MDL < MDL < MDL 0.013
Phorate 245 0.41 ND < MDL < MDL < MDL < MDL 0.033
Prometon 246 52.85 10.16 < MDL 0.013 0.05 0.077 0.31
Pronamide 246 1.63 0.41 < MDL < MDL < MDL < MDL 0.43
Propachlor 246 1.63 ND < MDL < MDL < MDL < MDL 0.030
Propanil 246 ND ND < MDL < MDL < MDL < MDL < MDL
Propargite 245 1.63 0.41 < MDL < MDL < MDL < MDL 2.0
Simazine 246 64.63 27.64 < MDL 0.017 0.13 0.21 1.3
Tebuthiuron 246 19.92 4.07 < MDL < MDL 0.019 0.038 0.17
Terbacil (E) 244 2.05 0.41 < MDL < MDL < MDL < MDL 0.08E
Terbufos 245 ND ND < MDL < MDL < MDL < MDL 0.010
Thiobencarb 245 0.41 ND < MDL < MDL < MDL < MDL 0.026
Triallate 245 2.04 0.41 < MDL < MDL < MDL 0.005 0.067
Trifluralin 245 4.49 ND < MDL < MDL 0.007 0.008 0.023
2,4,5-T 219 -- ND < MDL < MDL < MDL < MDL < MDL
2,4-D 219 -- 8.22 < MDL < MDL < MDL 0.11 0.76
2,4-DB 219 -- ND < MDL < MDL < MDL < MDL < MDL
3-OH-carbofuran 222 -- ND < MDL < MDL < MDL < MDL < MDL
Acifluorfen 219 -- 2.74 < MDL < MDL < MDL < MDL .058
Aldicarb (E) 222 -- ND < MDL < MDL < MDL < MDL < MDL
Aldicarb sulfone (E) 222 -- ND < MDL < MDL < MDL < MDL < MDL
Aldicarb sulfoxide (E) 222 -- ND < MDL < MDL < MDL < MDL < MDL
Bentazon 219 -- 8.22 < MDL < MDL < MDL 0.18 2.8
Bromacil 222 -- ND < MDL < MDL < MDL < MDL < MDL
Bromoxynil 219 -- ND < MDL < MDL < MDL < MDL < MDL
Chloramben 222 -- ND < MDL < MDL < MDL < MDL < MDL
Chlorothalonil (E) 221 -- ND < MDL < MDL < MDL < MDL < MDL
Clopyralid 219 -- ND < MDL < MDL < MDL < MDL < MDL
Dacthal mono-acid 219 -- ND < MDL < MDL < MDL < MDL < MDL
Dicamba 219 -- 1.83 < MDL < MDL < MDL < MDL 0.13
Dichlobenil (E) 222 -- 0.45 < MDL < MDL < MDL < MDL 0.05E
Dichlorprop 219 -- ND < MDL < MDL < MDL < MDL 0.04
Dinoseb 219 -- ND < MDL < MDL < MDL < MDL < MDL
Diuron 222 -- 8.56 < MDL < MDL < MDL 0.21 1.2
DNOC (E) 219 -- ND < MDL < MDL < MDL < MDL < MDL
Fenuron 222 -- ND < MDL < MDL < MDL < MDL 1.02
Fluometuron 222 -- ND < MDL < MDL < MDL < MDL < MDL
MCPA 219 -- ND < MDL < MDL < MDL < MDL < MDL
MCPB 219 -- ND < MDL < MDL < MDL < MDL < MDL
Methiocarb 222 -- 0.45 < MDL < MDL < MDL < MDL 0.23
Methomyl 222 -- ND < MDL < MDL < MDL < MDL < MDL
Neburon 222 -- ND < MDL < MDL < MDL < MDL < MDL
Norflurazon 222 -- ND < MDL < MDL < MDL < MDL < MDL
Oryzalin 222 -- 0.45 < MDL < MDL < MDL < MDL 0.43
Oxamyl 222 -- ND < MDL < MDL < MDL < MDL < MDL
Picloram 219 -- ND < MDL < MDL < MDL < MDL < MDL
Propham 222 -- ND < MDL < MDL < MDL < MDL < MDL
Propoxur 221 -- ND < MDL < MDL < MDL < MDL < MDL
Silvex 219 -- ND < MDL < MDL < MDL < MDL < MDL
Triclopyr 219 -- ND < MDL < MDL < MDL < MDL < MDL
* Acetochlor was not used prior to 1994, and was not targeted at most sites during the sampling periods used for table 4. See Table 1 for more complete results for acetochlor.
USGS Station ID Site Name Start date End date Number of Number of
GCMS HPLC
samples samples
AGRICULTURAL INDICATOR SITES
02356980 Aycocks Creek near Boykin, GA 93-3-15 94-3-2 22 22
02350080 Lime Creek near Cobb, GA 93-3-16 94-3-14 43 43
02084558 Albemarle Canal near Swindell NC 93-3-3 94-2-15 30 27
02082731 Devils Cradle Creek near Alert NC 93-3-1 94-2-9 26 22
02083833 Pete Mitchell Swamp near Penny Hill, NC 93-3-4 94-2-3 33 29
12464770 Crab Creek near Ritzville, WA 93-4-5 94-3-7 18 18
12472380 Crab Creek Lateral near Othello, WA 93-3-31 94-3-8 25 25
12473740 El 68 Wasteway near Othello, WA 93-4-1 94-3-9 25 25
13351000 Palouse River at Hooper, WA 93-4-6 94-3-7 21 21
06800000 Maple Creek near Nickerson NE 93-4-15 94-3-16 13 11
06773050 Prairie Creek near Ovina, NE 93-4-13 94-3-16 15 12
06795500 Shell Creek near Columbus, NE 93-4-30 94-3-15 14 12
02317797 Little River near Tifton, GA 93-3-17 94-3-3 24 23
02215100 Tucsawhatchee Creek near Hawkinsville, GA 93-3-18 94-3-4 39 39
01349150 Canajoharie Creek near Canajoharie, NY 94-3-15 95-2-14 19 16
01555400 East Mahantango Creek at Klingerstown, PA 93-3-30 94-3-25 33 32
01576540 Mill Creek near Lyndon, PA 93-4-7 94-4-6 31 31
06923150 Dousinbury Creek near Wall Street, MO 94-2-7 95-1-9 22 24
07053250 Yocum creek near Oak Grove, AR 94-2-8 95-1-10 23 24
01639000 Monocacy River at Bridgeport, MD 94-3-22 95-3-15 32 33
01621050 Muddy Creek at Mount Clinton, VA 93-3-29 94-3-28 33 32
05085900 Snake River above Alvarado, MN 93-4-1 94-3-21 25 22
05082625 Turtle River near Arvilla, ND 93-3-28 94-3-22 23 22
05062500 Wild Rice River at Twin Valley, MN 93-3-31 94-3-25 22 22
372214105491210 La Jara Creek near Alamosa, CO 94-4-7 94-9-7 23 23
11273500 Merced River near Stevinson, CA 93-3-18 94-2-23 33 31
11274538 Orestimba Creek near Crows Landing, CA 92-12-15 93-11-17 38 20
11261100 Salt Slough near Stevinson, CA 93-1-20 93-11-17 26 18
06753990 Lonetree Creek near Greeley, CO 93-4-1 94-3-9 23 23
08064100 Chambers Creek near Rice, TX 93-12-16 94-12-15 18 18
294349094345999 East Fork Double Bayou near Anahuac, TX 94-3-5 95-2-22 21 21
295001094384699 Whites Bayou near Anahuac, TX 94-3-5 95-2-22 21 21
13092747 Rock Creek at Twin Falls, ID 93-4-20 94-3-16 25 25
13055000 Teton River near St. Anthony, ID 93-5-5 94-5-2 24 24
03360895 Kessinger Ditch near Monroe City, IN 93-3-31 94-3-22 30 30
394340085524601 Sugar Creek at New Palestine, IN 93-3-23 94-3-14 35 35
14202000 Pudding River at Aurora, OR 93-5-28 94-5-25 16 16
14201300 Zollner Creek near Mt. Angel, OR 93-4-14 94-3-15 18 17
04072050 Duck Creek near Oneida, WI 93-4-7 94-3-18 20 20
040863075 North Branch Milwaukee River near Random Lake, WI 93-3-11 93-9-21 19 19
URBAN INDICATOR SITES
02335870 Sope creek near Marietta, GA 93-3-18 94-3-9 45 42
01209710 Norwalk River at Winnipauk, CT 93-3-17 94-3-14 34 35
02326838 Lafayette Creek near Talahassee, FL 93-3-10 94-3-2 28 26
01571490 Cedar Run at Eberlys Mill, PA 93-3-25 94-3-23 33 32
01356190 Lisha Kill near Niskayuna, NY 94-3-14 95-3-6 21 17
094196783 Las Vegas Wash near Las Vegas, NV 93-6-15 94-5-31 29 29
01654000 Accotink Creek near Annandale, VA 94-3-16 95-3-13 36 35
06713500 Cherry Creek at Denver, CO 93-4-12 94-3-29 23 22
08049240 Rush Creek at Arlington, TX 93-3-23 94-5-17 22 22
03353637 Little Buck Creek near Indianapolis, IN 93-3-22 94-3-14 33 33
14206950 Fanno Creek near Portland, OR 93-4-12 95-3-7 23 22
INTEGRATOR SITES
02083500 Tar River at Tarboro, NC 93-3-10 94-2-15 19 16
06805500 Platte River at Louisville, NE 93-4-26 94-3-18 14 12
02318500 Withlacoochee River near Quitman, GA 93-3-23 94-3-16 26 26
0]1357500 Mohawk River at Cohoes, NY 94-3-16 95-3-8 19 16
01636500 Shenandoah River at Millville, WV 93-3-30 94-2-15 13 13
05102490 Red River of the North at Pembina, ND 93-4-7 94-1-5 19 19
05053800 Red River of the North above Fargo, ND 94-4-4 95-3-19 10 10
08364000 Rio Grande River at El Paso, TX 95-1-7 95-11-2 6 1
11303500 San Joaquin River near Vernalis, Ca 93-3-18 94-2-23 27 25
06714000 South Platte River at Denver, CO 93-12-13 94-11-17 18 17
08057410 Trinity River at Dallas, TX 94-10-19 95-8-30 11 11
03374100 White River at Hazleton IN 93-3-30 94-3-5 31 31
14211720 Willamette River at Portland, OR 94-2-14 95-1-24 13 6
04087000 Milwaukee River at Milwaukee, WI 93-4-8 94-1-26 20 20
Tables 6-9 summarize the results of NAWQA sampling for pesticides in ground water within the first 20 NAWQA study units. Table 6summarizes data for every NAWQA ground-water sample that was analyzed for pesticides, including newly drilled monitoring wells, production wells (such as domestic and public-supply wells), springs, and tile drains. The objective of Table 6 is to provide a complete summary of all NAWQA results and a basis for comparison with the complete ground-water data set available for downloading (link to url). The information in this table can provide a cross-check for data downloaded to personal computer systems. Table 6 SHOULD NOT be presumed to be a statistically representative summary of the NAWQA pesticide results. The data in the table contain a variety of spatial and temporal biases for which corrections must be applied before any reliable statistical summaries can be compiled. For example, many of the sites were sampled more than once for pesticides. Failure to account for this feature in a statistical summary would of those sites in a statistical summary would lead to an over- representation of these sites.
In order to generate unbiased statistical summaries of the pesticide data in ground water, the following procedures were implemented using data from NAWQA ground water sampling networks ( http://water.wr.usgs.gov/pnsp/fy91sum.html).
Once an unbiased pesticide dataset was created, statistical summaries of the ground-water data were generated for three different settings: shallow ground water in primarily agricultural areas (Table 7), shallow ground water in primaily urban areas (Table 8), and major aquifers (Table 9). The agricultural and urban land-use categories were derived from sites designed to sample shallow, recently recharged ground water to determine the effects of specific land uses on water quality. Sites comprising the major aquifer category had no such restrictions on land use or water age, and thus, represent a broader mixture of land uses and ground-water depths.
Within each statistical summary, three detection frequencies are provided (all detections, >=0.01 ug/L, and >=0.05 ug/L). These detection frequencies provide a measure of "how often" a compound was found. The "all detections" provide the total number of detections for a given compound, but are not comparable among compounds because detection capabilities vary. Because the analytical detection limits varied among the different pesticide compounds examined, two detection thresholds were used (0.01 and 0.05 ug/L). The use of detection thresholds facilitates cross-comparisons among compounds by bringing most of the data to a common reference point. Adjustments of this type are essential in order to answer questions like "is compound x found more often than compound y?".
Also provided with each statistical summary are five measures of "how much" of a given compound was found in ground water. The 10th, 50th, 90th, and 95th percentiles reflect the percent of sites with concentrations less than or equal to a specific value. Thus, for example, a 90th- percentile concentration 0.04 ug/L for a given compound implies that 90 percent of the sites sampled for that compound in ground water were less than or equal to that level. The maximum concentration for a given compound shows the highest concentration encountered in ground water among all sites sampled.
All compounds denoted with (E) have more variable analytical performance than other compounds and usually much lower recoveries. Individual maximum values with an E-code have greater uncertainty because the values were beyond the calibration range.( http://water.wr.usgs.gov/pnsp/anstrat/).
DETECTION FREQUENCY (%) CONCENTRATION PERCENTILES (ug/L)
COMPOUND WELLS >MDL >=.01 ug/L >=.05 ug/L 10th 50th 90th 95th max
2,6-Diethylaniline 3023 0.79 0.20 0.03 < MDL < MDL < MDL < MDL 0.05
Acetochlor 1313 0.15 0.15 0.08 < MDL < MDL < MDL < MDL 0.11
Alachlor 3024 3.04 1.95 1.03 < MDL < MDL < MDL < MDL 10E
Atrazine 3024 32.90 21.66 11.90 < MDL < MDL 0.068 0.21 4.2
Atrazine, deethyl (E) 3024 31.55 19.64 10.02 < MDL < MDL 0.05 0.13 2.6E
Azinphos-methyl (E) 3015 0.13 0.10 0.07 < MDL < MDL < MDL < MDL 0.18E
Benfluralin 3023 0.10 0.00 0.00 < MDL < MDL < MDL < MDL 0.006
Butylate 3023 0.40 0.10 0.00 < MDL < MDL < MDL < MDL 0.045
Carbaryl (E) 3024 0.89 0.69 0.00 < MDL < MDL < MDL < MDL 0.036E
Carbofuran (E) 3024 0.50 0.46 0.26 < MDL < MDL < MDL < MDL 1.3E
Chlorpyrifos 3023 0.30 0.07 0.00 < MDL < MDL < MDL < MDL 0.026
Cyanazine 3024 2.48 1.95 0.89 < MDL < MDL < MDL < MDL 1.6
DCPA 3023 0.66 0.07 0.03 < MDL < MDL < MDL < MDL 10E
DDE, p,p' 3017 3.18 0.00 0.00 < MDL < MDL < MDL < MDL 0.006
Diazinon 3023 1.69 1.06 0.30 < MDL < MDL < MDL < MDL 0.16
Dieldrin 3023 1.42 0.93 0.10 < MDL < MDL < MDL < MDL 0.068
Disulfoton 3023 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
EPTC 3023 0.79 0.33 0.13 < MDL < MDL < MDL < MDL 0.45
Ethalfluralin 3023 0.10 0.03 0.03 < MDL < MDL < MDL < MDL 0.09
Ethoprop 3024 0.03 0.00 0.00 < MDL < MDL < MDL < MDL 0.009
Fonofos 3023 0.10 0.07 0.03 < MDL < MDL < MDL < MDL 0.059
HCH, alpha 3023 0.03 0.03 0.03 < MDL < MDL < MDL < MDL 0.059
HCH, gamma 3023 0.10 0.07 0.00 < MDL < MDL < MDL < MDL 0.032
Linuron 3023 0.10 0.07 0.03 < MDL < MDL < MDL < MDL 0.61
Malathion 3023 0.33 0.13 0.03 < MDL < MDL < MDL < MDL 0.1
Methyl parathion 3023 0.07 0.07 0.03 < MDL < MDL < MDL < MDL 0.062
Metolachlor 3024 15.48 7.08 2.38 < MDL < MDL 0.005 0.015 5.4
Metribuzin 3023 1.95 1.36 0.17 < MDL < MDL < MDL < MDL 0.3
Molinate 3023 0.13 0.10 0.03 < MDL < MDL < MDL < MDL 0.11
Napropamide 3024 0.17 0.13 0.03 < MDL < MDL < MDL < MDL 0.07
Parathion 3023 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Pebulate 3023 0.13 0.03 0.03 < MDL < MDL < MDL < MDL 0.052
Pendimethalin 3023 0.40 0.36 0.07 < MDL < MDL < MDL < MDL 0.12
Permethrin, cis 3023 0.07 0.00 0.00 < MDL < MDL < MDL < MDL 0.007
Phorate 3023 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Prometon 3024 10.85 7.84 3.47 < MDL < MDL 0.004 0.029 40E
Pronamide 3024 0.07 0.07 0.03 < MDL < MDL < MDL < MDL 0.052
Propachlor 3024 0.23 0.07 0.03 < MDL < MDL < MDL < MDL 0.057
Propanil 3024 0.40 0.10 0.00 < MDL < MDL < MDL < MDL 0.015
Propargite 3023 0.07 0.00 0.00 < MDL < MDL < MDL < MDL 0.009
Simazine 3024 15.91 9.52 3.27 < MDL < MDL 0.009 0.024 1.3
Tebuthiuron 3024 3.37 2.25 0.86 < MDL < MDL < MDL < MDL 0.79
Terbacil (E) 3000 0.40 0.27 0.20 < MDL < MDL < MDL < MDL 0.33E
Terbufos 3023 0.07 0.03 0.00 < MDL < MDL < MDL < MDL 0.012
Thiobencarb 3023 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Triallate 3023 0.17 0.00 0.00 < MDL < MDL < MDL < MDL 0.002
Trifluralin 3023 0.63 0.20 0.13 < MDL < MDL < MDL < MDL 0.15
2,4,5-T 2602 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
2,4-D 2602 0.38 -- 0.31 < MDL < MDL < MDL < MDL 0.54
2,4-DB 2602 0.04 -- 0.04 < MDL < MDL < MDL < MDL 0.06
3-OH-carbofuran 2596 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Acifluorfen 2604 0.04 -- 0.04 < MDL < MDL < MDL < MDL 0.19
Aldicarb (E) 2601 0.08 -- 0.04 < MDL < MDL < MDL < MDL 0.08E
Aldicarb sulfone (E) 2553 0.12 -- 0.08 < MDL < MDL < MDL < MDL 0.32E
Aldicarb sulfoxide (E) 2553 0.39 -- 0.35 < MDL < MDL < MDL < MDL 1.8E
Bentazon 2602 1.19 -- 1.00 < MDL < MDL < MDL < MDL 6.4
Bromacil 2613 0.92 -- 0.73 < MDL < MDL < MDL < MDL 14E
Bromoxynil 2602 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Chloramben 2612 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Chlorothalonil (E) 2597 0.04 -- 0.04 < MDL < MDL < MDL < MDL 0.23
Clopyralid 2589 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Dacthal mono-acid 2601 0.04 -- 0.04 < MDL < MDL < MDL < MDL 1.1
Dicamba 2601 0.15 -- 0.15 < MDL < MDL < MDL < MDL 2.5
Dichlobenil (E) 2612 0.23 -- 0.19 < MDL < MDL < MDL < MDL 0.21E
Dichlorprop 2602 0.08 -- 0.04 < MDL < MDL < MDL < MDL 0.14
Dinoseb 2603 0.19 -- 0.19 < MDL < MDL < MDL < MDL 7.9E
Diuron 2608 1.84 -- 0.96 < MDL < MDL < MDL < MDL 2.0
DNOC (E) 2602 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Fenuron 2596 0.04 -- 0.04 < MDL < MDL < MDL < MDL 0.14
Fluometuron 2612 1.88 -- 1.61 < MDL < MDL < MDL < MDL 4.7
MCPA 2601 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
MCPB 2602 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Methiocarb 2610 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Methomyl 2553 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Neburon 2610 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Norflurazon 2612 0.65 -- 0.61 < MDL < MDL < MDL < MDL 19E
Oryzalin 2610 0.08 -- 0.08 < MDL < MDL < MDL < MDL 0.08
Oxamyl 2550 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Picloram 2536 0.20 -- 0.20 < MDL < MDL < MDL < MDL 2.2
Propham 2611 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Propoxur 2572 0.08 -- 0.08 < MDL < MDL < MDL < MDL 0.3
Silvex 2604 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Triclopyr 2605 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
1,2-dichloropropane 1985 1.21 -- -- < MDL < MDL < MDL < MDL 7.5
1,2,3-trichloropropane 1985 0.76 -- -- < MDL < MDL < MDL < MDL 1.1
cis-1,3-dichloropropene 1985 0.00 -- -- < MDL < MDL < MDL < MDL --
trans-1,3-dichloropropene 1985 0.00 -- -- < MDL < MDL < MDL < MDL --
DBCP 1990 1.01 -- -- < MDL < MDL < MDL < MDL 3.7
EDB 1990 0.30 -- -- < MDL < MDL < MDL < MDL 1.4
Methyl bromide 1985 0.05 -- -- < MDL < MDL < MDL < MDL 0.5
DETECTION FREQUENCY (%) CONCENTRATION PERCENTILES (ug/L)
COMPOUND WELLS >MDL >=.01 ug/L >=.05 ug/L 10th 50th 90th 95th max
2,6-Diethylaniline 924 1.19 0.43 0.00 < MDL < MDL < MDL < MDL 0.049
Acetochlor 530 0.25 0.25 0.00 < MDL < MDL < MDL < MDL 0.023
Alachlor 925 3.14 1.49 0.54 < MDL < MDL < MDL < MDL 0.55
Atrazine 925 43.72 31.78 19.89 < MDL < MDL 0.21 0.375 3.6
Atrazine, deethyl (E) 925 42.27 29.08 17.94 < MDL < MDL 0.14 0.3 2.6E
Azinphos-methyl (E) 919 0.44 0.33 0.22 < MDL < MDL < MDL < MDL 0.18E
Benfluralin 924 0.11 0.00 0.00 < MDL < MDL < MDL < MDL 0.004
Butylate 924 0.32 0.00 0.00 < MDL < MDL < MDL < MDL 0.002
Carbaryl (E) 925 0.32 0.22 0.00 < MDL < MDL < MDL < MDL 0.019E
Carbofuran (E) 925 0.76 0.65 0.43 < MDL < MDL < MDL < MDL 1.3E
Chlorpyrifos 924 0.54 0.32 0.11 < MDL < MDL < MDL < MDL 0.006
Cyanazine 925 1.73 1.19 0.54 < MDL < MDL < MDL < MDL 0.16
DCPA 924 1.41 0.22 0.11 < MDL < MDL < MDL < MDL 10E
DDE, p,p' 923 3.68 0.00 0.00 < MDL < MDL < MDL < MDL 0.006
Diazinon 924 0.54 0.43 0.11 < MDL < MDL < MDL < MDL 0.077
Dieldrin 924 0.97 0.65 0.11 < MDL < MDL < MDL < MDL 0.057
Disulfoton 924 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
EPTC 924 1.62 0.65 0.33 < MDL < MDL < MDL < MDL 0.45
Ethalfluralin 924 0.33 0.11 0.11 < MDL < MDL < MDL < MDL 0.09
Ethoprop 925 0.11 0.00 0.00 < MDL < MDL < MDL < MDL 0.009
Fonofos 924 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
HCH, alpha 924 0.11 0.11 0.11 < MDL < MDL < MDL < MDL 0.059
HCH, gamma 924 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Linuron 924 0.11 0.11 0.00 < MDL < MDL < MDL < MDL 0.029
Malathion 924 0.32 0.11 0.11 < MDL < MDL < MDL < MDL 0.1
Methyl parathion 924 0.22 0.22 0.11 < MDL < MDL < MDL < MDL 0.062
Metolachlor 925 18.37 8.00 3.13 < MDL < MDL 0.006 0.018 5.4
Metribuzin 924 3.46 2.81 0.43 < MDL < MDL < MDL < MDL 0.3
Molinate 924 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Napropamide 925 0.22 0.22 0.00 < MDL < MDL < MDL < MDL 0.014
Parathion 924 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Pebulate 924 0.32 0.11 0.11 < MDL < MDL < MDL < MDL 0.052
Pendimethalin 924 0.22 0.11 0.00 < MDL < MDL < MDL < MDL 0.012
Permethrin, cis 924 0.22 0.00 0.00 < MDL < MDL < MDL < MDL 0.007
Phorate 924 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Prometon 925 13.40 9.08 3.46 < MDL < MDL 0.008 0.032 40E
Pronamide 925 0.22 0.22 0.11 < MDL < MDL < MDL < MDL 0.052
Propachlor 925 0.32 0.00 0.00 < MDL < MDL < MDL < MDL 0.004
Propanil 925 0.76 0.11 0.00 < MDL < MDL < MDL < MDL 0.015
Propargite 924 0.11 0.00 0.00 < MDL < MDL < MDL < MDL 0.009
Simazine 925 22.38 13.30 4.54 < MDL < MDL 0.015 0.042 1.3
Tebuthiuron 925 1.73 1.08 0.32 < MDL < MDL < MDL < MDL 0.24
Terbacil (E) 919 0.87 0.54 0.44 < MDL < MDL < MDL < MDL 0.33E
Terbufos 924 0.11 0.00 0.00 < MDL < MDL < MDL < MDL 0.008
Thiobencarb 924 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Triallate 924 0.32 0.00 0.00 < MDL < MDL < MDL < MDL 0.002
Trifluralin 924 0.43 0.00 0.00 < MDL < MDL < MDL < MDL 0.007
2,4,5-T 893 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
2,4-D 893 0.45 -- 0.34 < MDL < MDL < MDL < MDL 0.54
2,4-DB 893 0.11 -- 0.11 < MDL < MDL < MDL < MDL 0.06
3-OH-carbofuran 896 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Acifluorfen 894 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Aldicarb (E) 897 0.11 -- 0.00 < MDL < MDL < MDL < MDL 0.01E
Aldicarb sulfone (E) 883 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Aldicarb sulfoxide (E) 883 0.34 -- 0.34 < MDL < MDL < MDL < MDL 1.8E
Bentazon 893 1.01 -- 1.01 < MDL < MDL < MDL < MDL 2.7
Bromacil 897 1.23 -- 1.00 < MDL < MDL < MDL < MDL 14E
Bromoxynil 897 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Chloramben 897 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Chlorothalonil (E) 896 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Clopyralid 890 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Dacthal mono-acid 893 0.11 -- 0.11 < MDL < MDL < MDL < MDL 1.1
Dicamba 893 0.11 -- 0.11 < MDL < MDL < MDL < MDL 0.14
Dichlobenil (E) 897 0.33 -- 0.22 < MDL < MDL < MDL < MDL 0.13E
Dichlorprop 894 0.11 -- 0.00 < MDL < MDL < MDL < MDL 0.01E
Dinoseb 894 0.34 -- 0.34 < MDL < MDL < MDL < MDL 7.9E
Diuron 897 2.34 -- 1.23 < MDL < MDL < MDL < MDL 2.0
DNOC (E) 893 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Fenuron 896 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Fluometuron 897 0.45 -- 0.33 < MDL < MDL < MDL < MDL 0.43
MCPA 893 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
MCPB 893 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Methiocarb 897 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Methomyl 883 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Neburon 897 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Norflurazon 897 0.11 -- 0.11 < MDL < MDL < MDL < MDL 0.22
Oryzalin 897 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Oxamyl 882 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Picloram 878 0.11 -- 0.00 < MDL < MDL < MDL < MDL 2.2
Propham 897 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Propoxur 896 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Silvex 894 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Triclopyr 895 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
1,2-dichloropropane 742 1.75 -- -- < MDL < MDL < MDL < MDL 7.5
1,2,3-trichloropropane 742 1.08 -- -- < MDL < MDL < MDL < MDL 1.1
cis-1,3-dichloropropene 742 0.00 -- -- < MDL < MDL < MDL < MDL --
trans-1,3-dichloropropene 742 0.00 -- -- < MDL < MDL < MDL < MDL --
DBCP 739 1.35 -- -- < MDL < MDL < MDL < MDL 2.5
EDB 739 0.41 -- -- < MDL < MDL < MDL < MDL 1.4
Methyl bromide 742 0.00 -- -- < MDL < MDL < MDL < MDL --
DETECTION FREQUENCY (%) CONCENTRATION PERCENTILES (ug/L)
COMPOUND WELLS >MDL >=.01 ug/L >=.05 ug/L 10th 50th 90th 95th max
2,6-Diethylaniline 301 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Acetochlor 195 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Alachlor 301 0.33 0.00 0.00 < MDL < MDL < MDL < MDL 0.007
Atrazine 301 24.25 14.95 6.64 < MDL < MDL 0.018 0.061 4.2
Atrazine, deethyl (E) 301 20.27 10.63 4.32 < MDL < MDL 0.01 0.041 0.56E
Azinphos-methyl (E) 298 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Benfluralin 301 0.33 0.00 0.00 < MDL < MDL < MDL < MDL 0.006
Butylate 301 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Carbaryl (E) 301 1.33 1.00 0.00 < MDL < MDL < MDL < MDL 0.021E
Carbofuran (E) 301 0.66 0.66 0.33 < MDL < MDL < MDL < MDL 0.058E
Chlorpyrifos 301 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Cyanazine 301 1.33 1.00 0.00 < MDL < MDL < MDL < MDL 0.017
DCPA 301 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
DDE, p,p' 301 1.99 0.00 0.00 < MDL < MDL < MDL < MDL 0.002
Diazinon 301 1.66 0.33 0.00 < MDL < MDL < MDL < MDL 0.01
Dieldrin 301 5.65 3.32 0.66 < MDL < MDL < MDL 0.005 0.068
Disulfoton 301 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
EPTC 301 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Ethalfluralin 301 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Ethoprop 301 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Fonofos 301 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
HCH, alpha 301 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
HCH, gamma 301 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Linuron 301 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Malathion 301 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Methyl parathion 301 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Metolachlor 301 9.97 3.99 1.00 < MDL < MDL < MDL 0.005 0.862
Metribuzin 301 1.66 0.33 0.00 < MDL < MDL < MDL < MDL 0.043
Molinate 301 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Napropamide 301 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Parathion 301 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Pebulate 301 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Pendimethalin 301 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Permethrin, cis 301 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Phorate 301 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Prometon 301 27.24 24.25 13.95 < MDL < MDL 0.082 0.22 10E
Pronamide 301 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Propachlor 301 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Propanil 301 0.33 0.33 0.00 < MDL < MDL < MDL < MDL 0.008
Propargite 301 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Simazine 301 15.28 11.30 3.65 < MDL < MDL 0.012 0.03 1.1
Tebuthiuron 301 6.31 5.65 2.33 < MDL < MDL < MDL 0.014 0.121
Terbacil (E) 298 0.34 0.34 0.00 < MDL < MDL < MDL < MDL 0.034E
Terbufos 301 0.33 0.33 0.00 < MDL < MDL < MDL < MDL 0.012
Thiobencarb 301 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Triallate 301 0.33 0.00 0.00 < MDL < MDL < MDL < MDL 0.001
Trifluralin 301 0.66 0.33 0.00 < MDL < MDL < MDL < MDL 0.014
2,4,5-T 288 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
2,4-D 288 1.04 -- 1.04 < MDL < MDL < MDL < MDL 0.34
2,4-DB 288 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
3-OH-carbofuran 286 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Acifluorfen 288 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Aldicarb (E) 288 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Aldicarb sulfone (E) 278 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Aldicarb sulfoxide (E) 278 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Bentazon 288 0.35 -- 0.35 < MDL < MDL < MDL < MDL 0.76
Bromacil 289 2.42 -- 2.08 < MDL < MDL < MDL < MDL 3.0
Bromoxynil 288 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Chloramben 289 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Chlorothalonil (E) 285 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Clopyralid 285 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Dacthal mono-acid 288 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Dicamba 288 0.35 -- 0.35 < MDL < MDL < MDL < MDL 0.21
Dichlobenil (E) 289 0.35 -- 0.35 < MDL < MDL < MDL < MDL 0.21E
Dichlorprop 288 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Dinoseb 288 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Diuron 289 2.77 -- 1.73 < MDL < MDL < MDL < MDL 0.46
DNOC (E) 288 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Fenuron 286 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Fluometuron 289 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
MCPA 288 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
MCPB 288 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Methiocarb 289 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Methomyl 278 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Neburon 289 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Norflurazon 289 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Oryzalin 289 0.69 -- 0.69 < MDL < MDL < MDL < MDL 0.08
Oxamyl 278 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Picloram 281 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Propham 289 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Propoxur 288 0.35 -- 0.35 < MDL < MDL < MDL < MDL 0.3
Silvex 288 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Triclopyr 288 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
1,2-dichloropropane 304 0.33 -- -- < MDL < MDL < MDL < MDL 0.20
1,2,3-trichloropropane 304 0.00 -- -- < MDL < MDL < MDL < MDL --
cis-1,3-dichloropropene 304 0.00 -- -- < MDL < MDL < MDL < MDL --
trans-1,3-dichloropropene 304 0.00 -- -- < MDL < MDL < MDL < MDL --
DBCP 304 0.00 -- -- < MDL < MDL < MDL < MDL --
EDB 304 0.00 -- -- < MDL < MDL < MDL < MDL --
Methyl bromide 304 0.00 -- -- < MDL < MDL < MDL < MDL --
DETECTION FREQUENCY (%) CONCENTRATION PERCENTILES (ug/L)
COMPOUND WELLS >MDL >=.01 ug/L >=.05 ug/L 10th 50th 90th 95th max
2,6-Diethylaniline 933 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Acetochlor 389 0.26 0.26 0.26 < MDL < MDL < MDL < MDL 0.11
Alachlor 933 1.61 0.86 0.54 < MDL < MDL < MDL < MDL 0.14
Atrazine 933 19.08 10.18 4.39 < MDL < MDL 0.01 0.036 2.6
Atrazine, deethyl (E) 933 17.47 9.86 5.47 < MDL < MDL 0.009 0.06 2.0E
Azinphos-methyl (E) 933 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Benfluralin 933 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Butylate 933 0.21 0.00 0.00 < MDL < MDL < MDL < MDL 0.004
Carbaryl (E) 933 0.86 0.86 0.00 < MDL < MDL < MDL < MDL 0.036E
Carbofuran (E) 933 0.54 0.54 0.21 < MDL < MDL < MDL < MDL 0.4E
Chlorpyrifos 933 0.21 0.00 0.00 < MDL < MDL < MDL < MDL 0.005
Cyanazine 933 0.32 0.21 0.00 < MDL < MDL < MDL < MDL 0.023
DCPA 933 0.43 0.00 0.00 < MDL < MDL < MDL < MDL 0.002
DDE, p,p' 931 2.36 0.00 0.00 < MDL < MDL < MDL < MDL 0.003
Diazinon 933 1.82 1.29 0.43 < MDL < MDL < MDL < MDL 0.085
Dieldrin 933 0.43 0.21 0.00 < MDL < MDL < MDL < MDL 0.03
Disulfoton 933 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
EPTC 933 0.32 0.11 0.00 < MDL < MDL < MDL < MDL 0.031
Ethalfluralin 933 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Ethoprop 933 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Fonofos 933 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
HCH, alpha 933 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
HCH, gamma 933 0.11 0.00 0.00 < MDL < MDL < MDL < MDL 0.009
Linuron 933 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Malathion 933 0.43 0.11 0.00 < MDL < MDL < MDL < MDL 0.013
Methyl parathion 933 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Metolachlor 933 5.47 2.79 0.96 < MDL < MDL < MDL 0.002 2.47
Metribuzin 933 0.75 0.32 0.00 < MDL < MDL < MDL < MDL 0.045
Molinate 933 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Napropamide 933 0.21 0.11 0.11 < MDL < MDL < MDL < MDL 0.07
Parathion 933 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Pebulate 933 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Pendimethalin 933 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Permethrin, cis 933 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Phorate 933 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Prometon 933 4.07 2.04 0.86 < MDL < MDL < MDL < MDL 1.3
Pronamide 933 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Propachlor 933 0.11 0.00 0.00 < MDL < MDL < MDL < MDL 0.004
Propanil 933 0.54 0.21 0.00 < MDL < MDL < MDL < MDL 0.015
Propargite 933 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Simazine 933 6.32 3.00 0.75 < MDL < MDL < MDL 0.003 0.11
Tebuthiuron 933 0.86 0.64 0.32 < MDL < MDL < MDL < MDL 0.79
Terbacil (E) 924 0.33 0.33 0.22 < MDL < MDL < MDL < MDL 0.277E
Terbufos 933 0.11 0.00 0.00 < MDL < MDL < MDL < MDL 0.008
Thiobencarb 933 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Triallate 933 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
Trifluralin 933 0.00 0.00 0.00 < MDL < MDL < MDL < MDL --
2,4,5-T 849 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
2,4-D 849 0.35 -- 0.24 < MDL < MDL < MDL < MDL 0.11
2,4-DB 849 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
3-OH-carbofuran 848 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Acifluorfen 850 0.12 -- 0.12 < MDL < MDL < MDL < MDL 0.19
Aldicarb (E) 850 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Aldicarb sulfone (E) 829 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Aldicarb sulfoxide (E) 829 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Bentazon 849 1.30 -- 1.06 < MDL < MDL < MDL < MDL 6.4
Bromacil 855 0.59 -- 0.47 < MDL < MDL < MDL < MDL 0.33
Bromoxynil 849 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Chloramben 854 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Chlorothalonil (E) 848 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Clopyralid 848 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Dacthal mono-acid 848 0.00 -- 0.00 < MDL < MDL < MDL < MDL 00
Dicamba 848 0.12 -- 0.12 < MDL < MDL < MDL < MDL 0.07
Dichlobenil (E) 854 0.23 -- 0.23 < MDL < MDL < MDL < MDL 0.09E
Dichlorprop 854 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Dinoseb 849 0.24 -- 0.24 < MDL < MDL < MDL < MDL 7.9E
Diuron 850 0.94 -- 0.71 < MDL < MDL < MDL < MDL 0.34
DNOC (E) 850 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Fenuron 848 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Fluometuron 854 0.12 -- 0.00 < MDL < MDL < MDL < MDL 0.04
MCPA 849 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
MCPB 849 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Methiocarb 850 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Methomyl 829 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Neburon 850 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Norflurazon 854 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Oryzalin 850 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Oxamyl 827 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Picloram 824 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Propham 853 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Propoxur 841 0.12 -- 0.12 < MDL < MDL < MDL < MDL 0.06
Silvex 850 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
Triclopyr 850 0.00 -- 0.00 < MDL < MDL < MDL < MDL --
1,2-dichloropropane 646 0.77 -- -- < MDL < MDL < MDL < MDL 1.6
1,2,3-trichloropropane 645 0.62 -- -- < MDL < MDL < MDL < MDL 0.6
cis-1,3-dichloropropene 645 0.00 -- -- < MDL < MDL < MDL < MDL --
trans-1,3-dichloropropene 645 0.00 -- -- < MDL < MDL < MDL < MDL --
DBCP 645 0.00 -- -- < MDL < MDL < MDL < MDL --
EDB 645 0.31 -- -- < MDL < MDL < MDL < MDL 0.90
Methyl bromide 645 0.16 -- -- < MDL < MDL < MDL < MDL 0.50