Max TWAM Max 95 % tile Max Concentration STATE Cluster Average Single Cluster Cluster Average Single Cluster Cluster Average Single Cluster Max Moving Average DE 0.002 0.003 0.006 0.007 0.006 0.008 0.005 IA 0.001 0.003 NA NA 0.002 0.06 NA IN 0.002 0.004 NA NA 0.003 0.006 NA MN 0.005 0.010 NA NA 0.007 0.014 NA NE 0.002 0.003 0.007 0.010 0.007 0.012 0.008 OH NA NA NA NA NA 0.003 NA PA 0.001 0.002 0.003 0.008 0.005 0.013 0.005 WI NA NA NA NA NA 0.003 NA Single Cluster = Statistic applies to all observed values for the given depth; Cluster Average = Statistic applies to concentrations averaged across wells for a given date for the depth listed; Max TWAM = Maximum time weighted average observed; Max 95% tile = Represents the amount of time during the calendar year the concentration was below the listed value; Maximum Moving Average = The single highest average for 3 consecutive values ( separately by cluster and depth) across all clusters; NA = Insufficient uncensored concentrations to compute the value 6.4.3. SGW Summary In addition to PGW studies, the ARP was required to monitor 25 wells in each of the expected seven high use states ( WI, IL, IA, MN, IN, NE, KS) shown in Figure 4. Sites ranged from vulnerable to general use conditions, including diverse geographic, soil, and climatic conditions. Numerous studies have demonstrated that the time to recharge of shallow superficial aquifer from the land surface can be several years or more ( including the results at some of the ARP's PGW sites  for acetochlor degradates). Therefore, the 7 years of state ground water monitoring data may under estimate the full potential leaching of acetochlor and its degradates to ground water if this chemical is used annually and with significant frequency for the next 10 or 20 years. Additional concerns relate to the lack of definitive confirmation by the ARP of a hydraulic connection between the ARP monitoring sites and  55

the sampled ground water ( i. e., data were not collected specifically to confirm the direction of vadose zone flow and transport during the course of the SGW study). The ARP states the following about how they obtained adequate justification of the locations of their wells in relation to fields treated with acetochlor as part of the SGW program:

Monitoring wells were sited within or closely adjacent to, and down gradient of the study plot. Various sources of published ground water data were used ( for example, the Department of Natural Resources Hydrologic Assessment, the USGS Hydrologic Atlas and local university data) to assess ground water flow direction for most sites. At sites where published ground water data were not available, trained hydrogeologists evaluated topography in conjunction with surface water drainage features in order to assess ground water flow direction. ( Source: De Guzman et al., in press).

The ARP did not attempt to determine the age of the ground water sampled at any location or confirm the travel times for water from the treated field to the sampled ground water via use of tracers. Some indication, at least, may be obtained of the intrinsic vulnerability of the ground water sampled to contamination from leachable pesticides by evaluation of the patterns of detection of other corn herbicides at the SGW sites ( atrazine, alachlor, metolachlor, and metabolites of alachlor and metolachlor were routinely analyzed along with acetochlor residues for in all well water samples).

The monitoring data serve as an early indication that pesticide residues may be reaching ground water. ARP found that parent acetochlor demonstrated a confirmed pattern of movement to ground water above 0.1 ppb at only seven sites. However, Table 1 of Appendix 12.8 indicates that acetochlor was detected above 0.1 ppb in 14 individual wells located across five states.

<IP_ADDRESS>. Comparison of SGW Results to Regulatory Action Endpoints In the SGW study parent acetochlor in seven of the approximately 175 wells ( there were some wells replaced and lost during the coarse of the study) exceeded a literal interpretation of the SGW regulatory trigger involving a pattern of detections at 0.10 ppb or greater ( 20 wells with such a pattern of detection would have triggered regulatory action to mitigate ground water contamination). The rate of detection of both acetochlor degradates was much higher than for parent over the 1999 to 2001 <IP_ADDRESS>. SGW Acute Exposure The distribution of maximum observed acetochlor concentrations for each site is given in Figure 14. Overall, the majority of values were reported as 0.05 ppb. No sites had detections of acetochlor greater than 8.0 ppb, and only one site had a maximum concentration between 4 and 8 ppb. Roughly 90% of the peak acetochlor values observed for each site were less than or equal to 0.5 ppb.  56

Frequency Distribution for Acetochlor Numeric Re spons e ( SGW)

0 1 1 48 114 4 10 2 0 1 1 0 0 20 40 60 80 100 120 140 0 0.003 0.005 0.01 0.05 0.1 0.5 1 2 4 8 > 8 Concentration ( ppb) Frequency 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Frequency Cumulative %

Figure 14. Distribution of maximum acetochlor concentrations observed at each site in the state ground water program.

<IP_ADDRESS>. SGW Annual Means Time weighted annualized means were computed for each site in the SGW data set based on numeric response data submitted by the ARP. Figure 15 shows the frequency of each timeweighted annualized mean as well as the cumulative frequency distribution. A total of 1,207 annualized means were calculated, with roughly 85% of the TWAMs less than or equal to 0.003.

Frequency Distribution of all Time Weighted Annualized Means for the SGW sites.

27 1008 116 23 19 5 8 1 0 0 0 200 400 600 800 1000 1200 0 0.003 0.005 0.01 0.05 0.1 0.5 1 2 > 2 Concentrat ion ( ppb) Frequency 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Frequency Cumulative %

Figure 15. Distribution of all time weighted annualized means for sites in the state ground water ( SGW) monitoring program.  57

<IP_ADDRESS>. Ground Water Factor Analysis Several environmental variables in the PGW studies were examined to assess their role in observed acetochlor concentrations. Given that at most sites acetochlor was only applied in the first year of the study, this analysis used acute concentrations as the dependent variable. Acute exposure was analyzed individually for three and six foot lysimeters, as well as shallow groundwater. Several hydrogeologic and meteorological factors were selected as independent variables. Factors included average pore water velocity at each site, average hydraulic conductivity, average hydraulic gradient, precipitation for the first three months after treatment, annual precipitation for the 1st year after treatment, 2nd year, 3rd year, and 4th year after treatment, as well as total precipitation during the monitoring period. Results of the analysis are provided in Appendix Acute exposure in nine foot lysimeters was weakly correlated with annual precipitation 2 years after treatment. Acute exposure in shallow ground water was weakly correlated with total precipitation during the monitoring period, as well as acute exposure in nine foot lysimeters. None of the correlations were statistically significant at p = 0.05.

ARP's analysis of the state ground water monitoring program indicated that soil texture was originally hypothesized to be a factor in the geographic distribution of detections. Rather, the detection of acetochlor in shallow ground water was more influenced by site specific factors related to site topography, irrigation practices, surface water drainages, and the vertical location of the well screen. Based on the limited availability of data, and given that the scope of the current risk assessment does not attempt to predict concentrations in ground water, no further statistical analysis is warranted at this time.

7. RESIDUES  ACETOCHLOR DEGRADATES Although the purpose of this assessment is primarily to focus on exposure to the parent acetochlor, some attention was given to the two acetochlor degradates, ethanesulfonic acid ( ESA) and oxanilic acid ( OXA), monitored in this study. The Health Effects Division of OPP has determined that the toxicological profiles of parent acetochlor, ESA, and OXA Each of the two degradates were measured in all three monitoring programs. In addition to results for the individual degradates, total combined residues were computed for acetochlor. Each of the degradates were given the same weight as the parent acetochlor using equation three.

Equation 3:

CCombined Residue = Cparent + CESA + COXA, where C is the concentration in ppb.

Note that if at some point a risk assessment for combined residues would be needed, these calculations would have to be converted to a molar basis before application of any relevant potency factors to such an assessment.

7.1. Surface Water 7.1.1. Acute Exposure Distributions by SDWS Sites Acute exposure of acetochlor ethanesulfonic acid and oxanilic acid, as well as the combined residues and are presented as a cumulative distribution function in Figure 16. The lines indicate the frequency at  58

which the degradates or combined residues concentration were detected at or below a given concentration. In addition, as the CDF line shifts to the right it indicates a higher concentration at a given frequency. In general, maximum raw water concentrations were greater than finished water samples for both degradates and combined residues up to approximately 0.5 ppb. However, finished water concentrations exceeded maximum raw water once concentrations exceeded roughly 0.5 ppb. This shift in raw versus finished concentrations can be seen at the point where the dotted line intersects the solid line.

Degradate Acute Exposure in Finished Samples ( SDWS)

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

0 0.003 0.005 0.010 0.05 0.1 0.5 1 2 4 8 > 8 Concentration ( ppb) Frequency ESA  RAW ESA  FIN OXA  RAW OXA  FIN Total Res idue  RAW Total Res idue  FIN Figure 16. Maximum observed concentrations ( acute) of the two acetochlor degradates and Total Combined residues ( parent + ESA + OXA) in raw ( dashed) and finished ( solid) surface drinking water samples.  59

Percent reduction of ESA and OXA ( Figure 17) was also computed for dates where both a raw and finished water sample pair was available. In general OXA had a higher percent reduction than ESA. As with the parent acetochlor, in some cases the finished water sample was higher than the raw water sample as indicated by a negative percent reduction on the chart.

Degredate Percent Reduction 0 50 100 150 200 250 300 350 400 450  100  85  75  50  25 0 25 50 75 85 100 Percent Reduction Frequency 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% AcOXA Frequency AcESA Frequency AcOXA Cumulative %

AcESA Cumulative %

Figure 17. Percent reduction of acetochlor degradates in surface drinking water supplies.

7.1.2. Chronic Exposure Distributions Chronic exposure for acetochlor degradates and combined residues were also determined for the surface drinking water supplies. Figure 18 presents the cumulative distribution of chronic exposure based on the maximum time weighted annualized mean for each site. The total residue was computed by summing the concentrations for the parent and degradates. Therefore, the chart only reflects sample observations where a sample was analyzed for both the parent and degradates.

The chart demonstrates that overall, TWAMs for each of the degradates and total combined residues were higher in raw water samples ( dotted lines) than in finished water samples ( solid lines). This again emphasizes the importance of surface water treatment in reducing exposure to acetochlor degradates.  60

Frequency Distribution for MAX TWAM SDWS 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

0 0.003 0.005 0.01 0.05 0.1 0.5 1 2 4 8 > 8 Concentration ( ppb) Frequency AcESA Finished AcESA Raw AcOxa Finished AcOxa Raw Total residue Finished Total residue Raw Figure 18. Chronic exposure distribution for acetochlor degradates ( ESA and OXA) in surface drinking water supplies using the maximum time weighted annualized mean for each site. Summary of USGS monitoring results for acetochlor degradates 7.2. Ground Water Two separate data files were used in this analysis ( Table 5). One file contained all the concentration values observed in the PGW studies provided by the ARP, while the second contained raw uncensored concentrations also provided by the ARP. Under the assumption that it represented the best available estimates of unmeasured values ( any substitution method for nondetects would be arbitrary), the PGW uncensored file was used to compute time weighted annualized means and percentiles.

7.2.1. Comparison of Ground Water Degradate Monitoring results to Cancellation / Mitigation Endpoints.

The degradate data are discussed here with regard to the mitigation endpoints included in the acetochlor registration agreement, however, it is not anticipated that the compounds will needed to be included in the residues of concern for the drinking water risk assessment. The conditional registration agreement only requires mitigation or cancellation of acetochlor " residues of concern" once the presence of a " pattern of movement" as specified in the agreement is established. In the PGW studies, one indication of a pattern of movement was defined as the detection of acetochlor or any of its degradates greater than or equal to 1.0 ppb at nine foot lysimeter depth as well as corresponding three and 6 foot depths in that cluster. The Appendix ( Section 12.8 of this report) lists all the sites where acetochlor or either of its degradates equaled or exceeded 1.0 ppb at three, six, and nine foot depths. The acetochlor degradate OXA did not exceed 1.0 ppb at three, six, and nine foot depths in any cluster. However in 293 instances, ESA equaled  61

or exceeded 1.0 ppb at the nine foot lysimeter depth in clusters where ESA also exceeded 1.0 ppb at the three and six foot depths at some time over the course of investigation.

Seven out of the eight states in the PGW studies demonstrated a pattern of movement of ESA as defined by exceedence of 1.0 ppb in at least one cluster of lysimeters at three, six, and nine foot depths ( see " Data Tables for the ARP Monitoring Studies Related to Mitigation Endpoints" in the Appendix). Although the cancellation triggers apply only to the parent acetochlor, the pattern of movement demonstrated by the acetochlor degradates would be important if one of the degradates becomes a toxicological concern.

A cancellation endpoint for the parent acetochlor was the detection of acetochlor at 0.10 ppb or above in 20 or more wells in the state ground water monitoring program followed by two subsequent detections in monthly follow up samples within six months. Again, this does not presently apply to acetochlor degradates, however degradate data was compared to the endpoint for parent. A number of sites in the state ground water monitoring program had acetochlor degradate detections of at least 0.10 ppb as well as in two monthly follow up samples ( see Appendix, section 12.7).

7.2.2. PGW Acute Exposure by Site.

Distributions of peak concentrations by site using the maximum of any individual cluster are provided in Table 25. Data are summarized by the peak value across all clusters, as well as the average of all clusters for each depth. Because of the overwhelming number of censored values, maximum TWAMs as well as maximum 95th percentiles were computed based on the uncensored data file provided by the ARP ( Table 5). In addition, the maximum three consecutive sample running average for each of the eight PGW sites is included. A three consecutive running average was used to reduce the likelihood that the assessment would be based upon statistical outliers. A three value running average was chosen over a three month running average due to the frequency of sampling. In some cases observations were spaced more than one month apart as a result of sampling limitations, such as inclement weather or inadequate sample volume in the well or lysimeter.  62

Table 21. Concentrations of ESA observed in 9 foot lysimeters from the eight prospective ground water studies.

Max TWAM Max 95 % tile Max Concentration STATE Cluster Average Single Cluster Cluster Average Single Cluster Cluster Average Single Cluster Max Moving Average DE 0.77 2.48 1.31 3.90 1.70 4.30 3.73 IA 0.94 3.17 1.58 5.09 1.68 5.40 3.13 IN 5.79 18.29 9.79 23.39 13.00 24.00 22.67 MN 6.58 13.42 8.84 23.39 9.70 24.00 19.33 NE 2.26 9.21 2.32 11.19 2.33 11.40 11.03 OH 0.36 2.11 1.88 5.81 2.96 6.50 5.87 PA 1.13 2.53 1.41 3.50 1.42 3.59 3.39 WI 9.69 14.44 16.71 29.60 17.00 36.00 22.67 All values are as ppb ( ug/ L). Values below 0.2 ppb are not verifiable because of the detection limit of the analytical method. Single Cluster = Statistic applies to all observed values for the given depth; Cluster Average = Statistic applies to concentrations averaged across all clusters for a given date for the depth listed; Max TWAM = Maximum time weighted average based on uncensored data file; Max 95% tile = The amount of time during the calendar year the concentration was below the listed value based on uncensored data file; Maximum Moving Average = The single highest average for 3 consecutive values ( separately by cluster and depth) across all clusters based on uncensored data file; NA = Insufficient uncensored data to compute the value Table 22. Concentrations of ESA observed in shallow ground water from the eight prospective ground water studies.

Max TWAM Max 95 % tile Max Concentration STATE Cluster Average Single Cluster Cluster Average Single Cluster Cluster Average Single Cluster Max Moving Average DE 1.179 2.519 1.370 3.148 1.443 3.220 3.013 IA 0.123 0.240 0.287 0.728 0.312 0.766 0.644 IN 1.237 9.241 1.684 13.470 1.775 14.200 13.400 MN 1.523 3.015 2.592 6.423 2.698 7.700 6.067 NE < 0.2 < 0.2 < 0.2 < 0.2 < 0.2 < 0.2 < 0.2 OH < 0.2 < 0.2 < 0.2 < 0.2 < 0.2 < 0.2 < 0.2 PA 1.567 6.848 1.924 8.056 1.962 8.300 7.980 WI 3.533 8.054 4.590 10.679 4.736 11.000 8.133 All values are as ppb ( ug/ L). Values below 0.2 ppb are not verifiable because of the detection limit of the analytical method. Single Cluster = Statistic applies to all observed values for the given depth; Cluster Average = Statistic applies to concentrations averaged across all clusters for a given date for the depth listed; Max TWAM = Maximum time weighted average based on uncensored data file; Max 95% tile = The amount of time during the calendar year the concentration was below the listed value based on uncensored data file; Maximum Moving Average = The single highest average for 3 consecutive values ( separately by cluster and depth) across all clusters based on uncensored data file; NA = Insufficient uncensored data to compute the value  63

Table 23. Comparison of Acetochlor ESA and bromide breakthrough in 9 foot lysimeters at the eight prospective ground water monitoring sites: Normalized concentrations. 1 Application rates lb a. i. / acre Acetochlor ESA Max Concentration Bromide Max Concentration Acetochlor ESA Bromide STATE Acetochlor Bromide Cluster Average Single Cluster Cluster Average Single Cluster Max Moving Average Max Moving Average DE 2.05 89 0.829 2.098 40 80 1.820 52 IA 3.12 98 0.538 1.731 28 58 1.003 16 IN 2.5 98 5.200 9.600 31 61 9.068 23 MN 2.14 82 4.533 11.215 61 107 9.033 13 NE 3.12 98 0.747 3.654 80 133 3.535 125 OH 2.05 98 1.444 3.171 60 112 2.863 NA PA 3.12 89 0.455 1.151 18 28 1.087 12 WI 1.78 125 9.551 20.225 95 136 12.736 NA 1 Calculated concentration in ug/ L divided by the application rate as pound active ingredient per acre. This gives a comparable concentration for the tracer and pesticide degradate if the observed concentration is proportional to the application rate; Single Cluster = Statistic applies to all observed values for the given depth; Cluster Average = Statistic applies to concentrations averaged across all cluster for a given date for the depth listed; Max TWAM = Maximum timeweighted average observed; Max 95% tile = Represents the amount of time during the calendar year the concentration was below the listed value; Maximum Moving Average = The single highest average for 3 consecutive values ( separately by cluster and depth) across all clusters; NA = Insufficient uncensored data to compute the value Table 24. Comparison of Acetochlor ESA and bromide breakthrough ( with months after treatment) in shallow ground water at the eight prospective ground water monitoring sites: Normalized concentrations. 1 Application rates ( as lb ai/ A or lb Br/ A) ESA Max Concentration Bromide Max Concentration ESA Bromide STATE Acetochlor Bromide Cluster Average Single Cluster Cluster Average Single Cluster Max Moving Average Max Moving Average DE 2.05 59.8 0.702 1.571 98.0 120.6 1.868 114.7 ( 33) ( 33) ( 39) ( 29) ( 13.5) ( 31)

IA 3.12 65.8 0.112 0.160 31.3 62.6 1.003 65.5 ( 24) ( 22) ( 23) ( 23) ( 1.5) ( 28)

IN 2.5 65.8 0.684 5.200 29.8 86.4 9.068 81.9 ( 6) ( 6) ( 34) ( 34) ( 15) ( 15)

MN 2.14 55.1 1.280 3.598 38.7 73.0 9.033 146.0 ( 27) ( 30) ( 38) ( 27& 28) ( 13) ( 23)

NE 3.12 65.8 0.048 0.160 13.4 71.5 3.535 186.2 ( 34) ( 34) ( 54) ( 54) ( 83) ( 87)

OH 2.05 65.8 0.049 0.049 16.4 20.9 2.863 105.7 ( 7) () ( 11) ( 11) ( 4) ( 14)

PA 3.12 59.8 0.628 2.660 11.9 26.8 2.558 40.2 ( 55) ( 51) ( 41) ( 53) ( 54) ( 28)

WI 1.78 83.9 2.584 6.180 70.0 131.1 12.736 186.2 ( 24) ( 24) ( 24) ( 23) ( 14) ( 16) 1 Calculated concentration in ug/ L divided by the application rate as pound active ingredient per acre. This gives a comparable concentration for the tracer and pesticide degradate if the observed concentration is proportional to the application rate; single cluster = statistic applies to all observed values for the given depth; cluster average = statistic applies to concentrations averaged across all cluster for a given date for the depth listed; max TWAM = maximum timeweighted average observed; max 95% tile represents the amount of time during the calendar year the concentration was below the listed value; maximum moving average = the single highest average for 3 consecutive values ( separately by cluster and depth) across all clusters; NA = insufficient data in the uncensored file to compute the value. Italicized values in parenthesis for each site are the months after treatment that the ESA or Br concentration was observed.  64

Table 25. Concentrations of acetochlor OXA observed in 9 foot lysimeters from the eight prospective ground water studies.

Max TWAM Max 95 % tile Max Concentration STATE Cluster Average Single Cluster Cluster Average Single Cluster Cluster Average Single Cluster Max Moving Average DE < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 IA < 0.1 0.23 0.12 0.37 0.13 0.40 0.13 IN 0.58 1.16 0.69 1.38 0.75 1.50 0.50 MN 0.16 0.18 0.19 < 0.1 0.20 2.70 0.90 NE < 0.1 0.12 < 0.1 0.13 < 0.1 0.13 0.11 OH < 0.1 0.40 0.14 1.53 0.37 2.20 1.10 PA < 0.1 < 0.1 0.10 0.26 0.15 0.30 0.17 WI < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 All values are as ppb ( ug/ L). Values below 0.1 ppb are not verifiable because of the detection limit of the analytical method. Single Cluster = Statistic applies to all observed values for the given depth Cluster Average = Statistic applies to concentrations averaged across all clusters for a given date for the depth listed Max TWAM = Maximum time weighted average based on uncensored data file Max 95% tile = The amount of time during the calendar year the concentration was below the listed value based on uncensored data file. Maximum Moving Average = The single highest average for 3 consecutive values ( separately by cluster and depth) across all clusters based on uncensored data file. NA = Insufficient data in the uncensored file to compute the value Table 26. . Concentrations of acetochlor OXA observed in shallow ground water from the eight prospective ground water studies.

Max TWAM Max 95 % tile Max Concentration STATE Cluster Average Single Cluster Cluster Average Single Cluster Cluster Average Single Cluster Max Moving Average DE < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 IA < 0.1 < 0.1 < 0.1 0.176 < 0.1 0.200 < 0.1 IN < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 MN 0.207 0.296 0.874 1.339 1.300 1.400 1.100 NE < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 OH < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 PA < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 WI < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 All values are as ppb ( ug/ L). Values below 0.1 ppb are not verifiable because of the detection limit of the analytical method. Single Cluster = Statistic applies to all observed values for the given depth Cluster Average = Statistic applies to concentrations averaged across all clusters for a given date for the depth listed Max TWAM = Maximum time weighted average based on uncensored data file Max 95% tile = The amount of time during the calendar year the concentration was below the listed value based on uncensored data file. Maximum Moving Average = The single highest average for 3 consecutive values ( separately by cluster and depth) across all clusters based on uncensored data file. NA = Insufficient data in the uncensored file to compute the value  65

7.2.3. Chronic Exposure Chronic exposure for acetochlor degradates and combined residues were also determined for the state ground water monitoring program. Figure 19 presents the cumulative distribution of chronic exposure based on the maximum time weighted annualized mean for each site. The total residue was computed by summing the concentrations for the parent and degradates. As such, chart only reflects sample observations where a sample was analyzed for both the parent and degradates. Peak time weighted annualized means concentrations for acetochlor ESA in ground water were higher than those for acetochlor OXA in the state monitoring program ( Figure 19).

Chronic Exposure Cumulative Frequency Distribution Maximum TWAM for SGW Sites 0% 20% 40% 60% 80% 100% 120%

0 0.003 0.005 0.01 0.05 0.1 0.5 1 2 4 8 > 8 Concentration ( ppb) Frequency ESA OXA Total residue Figure 19. Chronic exposure distribution for acetochlor degradates ( ESA and OXA) in the state ground water monitoring program using the maximum time weighted annualized mean for each site.

7.3. Summary Assessment of Exposure to Acetochlor Degradates Unlike exposure to acetochlor parent alone, the concentration profiles for the ARP studies show that exposure to combined residues can be higher in ground water than surface water ( Table 27). The maximum annual mean concentrations in ground water were up to 8x greater than in surface water and the 95th percentile annual mean concentrations were up to about 5x greater than in surface water. The combined exposure levels however have not been used for the OPP human health risk assessment ( ACETOCHLOR. Revised HED Chapter of the Tolerance Reassessment Eligibility Decision ( TRED) Document. PC Code: 121601, DP Barcode: D306535, D292338; dated 11/ 8/ 2005). In the HED chapter the following is stated:  66

" based on comparison of the available toxicity data for acetochlor and the ESA and OXA degradates. ( summarized in Tables 3.2 3.4 of the ACETOCHLOR HED Chapter of the TRED) and structure activity relationships, the MARC concluded that: the ESA and OXA degradates of acetochlor should not be included in the water risk assessment with the parent."

HED has, however calculated the risk contribution from drinking water separately each for ESA and OXA for their respective, distinctively different acute and chronic toxicological endpoints. Again quoting from the HED Chapter of the TRED for acetochlor:

" Comparison of the toxicities of the ESA and OXA degradates with the toxicity of the parent acetochlor [ See Tables 3.2 and 3.3 of the ACETOCHLOR HED Chapter of the TRED] indicated that the degradates had distinct, different, toxicological profiles from the parent. Thus, endpoints for the risk assessment of the ESA and OXA degradates were searched within their respective databases."

EFED has therefore separately evaluated exposure to acetochlor ESA and acetochlor OXA by analysis of all of the ARP surface water and ground water monitoring studies ( unlike with parent acetochlor, ground water and surface water exposure are both frequently at relatively significant levels ( in terms of exposure frequency and amount, not in terms of risk level).

Key points to consider in the interpretation of these results are:

1. The surface water data, unlike the ground water data, represent actual drinking water intakes or finished water; however, many of the highest acetochlor use watersheds were not included in the monitoring program. 2. Since this monitoring program started immediately after the registration of acetochlor, the full extent of contamination of ground water possible from the use of acetochlor could not be assessed with confidence in the SGW program since it may take many years to observe the maximum extent of ground water contamination from the use of a pesticide. Even in the PGW program, there was one site ( Nebraska) where the leaching of an acetochlor degradate ( ESA) was still moving downward through the vadose zone when sampling was terminated seven years after the original ( and only) acetochlor application. 3. In both the SGW and PGW ground water monitoring programs, the water sampled was more vulnerable than most ( but not all) water used for drinking water. 4. The results of this monitoring analysis only apply to acetochlor use on field corn ( significant new field uses are currently under review by EPA).  67

The highest monitored values for acetochlor ESA were:

Acute exposure ( Table 28):

20.0 ppb ESA in a sample from one of the approximately 175 SGW study sites.

14.2 ppb ESA in a sample from one of the shallow wells from one of the eight PGW study sites.

4.8 ppb ESA in a sample from one of the approximately 175 SDWS study sites.

Chronic exposure ( Table 30):

12.7 ppb ESA TWAM from one of the SGW study sites.

9.2 ppb ESA TWAM from one of the shallow wells from one of the PGW study sites.

1.0 ppb ESA TWAM from one of the SDWS study sites.

The highest monitored values for acetochlor OXA were:

Acute exposure ( Table 29):

19.1 ppb OXA in a sample from a shallow well from one of the SGW study sites.

1.4 ppb OXA in a sample from one of the shallow wells from one of the PGW study sites.

6.3 ppb OXA in a sample from one of the SDWS study sites.

Chronic exposure ( Table 31):

5.9 ppb OXA TWAM from a shallow well from one of the SGW study sites.

Not calculated ( TWAM < 1 ppb for all wells) OXA for the eight PGW study sites.

1.7 ppb TWAM OXA from one of the approximately 175 SDWS study sites.

In general acetochlor ESA was detected more frequently at higher concentrations in both of the ground water studies than in the SDWS. The highest acetochlor OXA acute and chronic exposure levels occurred in ground water, but there was less overall difference in the residue levels between ground and surface than there was for ESA and the median acute and chronic values were actually higher in the SDWS than in the PGW or SGW studies.

Table 27. Summary presentation of time weighted annualized mean concentrations ( ppb) for the combined residues of acetochlor ( parent + ESA and OXA degradates) in surface and ground water ( based on maximum TWAM values observed at each site by calendar year).

Study N Maximum 95th Percentile Median  68

Table 27. Summary presentation of time weighted annualized mean concentrations ( ppb) for the combined residues of acetochlor ( parent + ESA and OXA degradates) in surface and ground water ( based on maximum TWAM values observed at each site by calendar year).

Study N Maximum 95th Percentile Median Surface Water  SDWS raw 43 2.04 1.67 0.31 Surface Water  SDWS finished 175 2.91 1.39 0.25 Ground Water ( shallow)   PGW site averages 8 3.51 2.83 1.12 Ground Water ( shallow)   PGW cluster maximums 8 8.11 7.57 2.85 Ground Water   SGW 176 24.11 3.24 0.08 Table 28. Acute Exposure to ESA. Summary presentation of acute concentrations ( ppb) for the residues of acetochlor ethanesulfonic acid in surface and ground water. Sample / Study Type (# of sites) N1 Maximu m 99th Percentile 95th Percentile Median Surface Water   SDWS raw 2 ( ca. 43 sites) 1496 2.310 1.000 0.633 < 0.200 Surface Water   SDWS finished 2 ( ca. 175 sites) 6774 3.320 1.133 0.571 < 0.200 Ground Water ( shallow)   PGW site averages by date ( 8 sites) 670 4.736 2.471 3 1.488 3 < 0.200 3 Ground Water ( shallow)   PGW single cluster basis ( 8 sites) NC 14.200 6.100 3 2.640 3 < 0.200 3 Ground Water   SGW ( ca. 175 sites) 1983 20.000 6.418 1.790 < 0.200 1 Number of samples represented. NC = Not calculated. 2 Comparisons between raw and finished water concentration distributions should be made with caution since most SDWS sites never had raw water sampled. Statistics based on monitoring for only the last three years of the study ( 1999 to 2001); this is also true for the SGW study. 3 Statistics here are less meaningful for the PGW studies because of the small number of study sites ( 8), the lag time between the start of sampling of ground water after application and breakthrough of any residues into ground water, and the lack of reproduction of long term use patterns in PGW studies ( i. e., generally only a one time application of acetochlor was made during the first growing season of  69

Table 28. Acute Exposure to ESA. Summary presentation of acute concentrations ( ppb) for the residues of acetochlor ethanesulfonic acid in surface and ground water. Sample / Study Type (# of sites) N1 Maximu m 99th Percentile 95th Percentile Median the study).

Table 29. Acute Exposure to OXA. Summary presentation of acute concentrations ( ppb) for the residues of acetochlor oxanilic acid in surface and ground water. Sample / Study Type (# of sites) N1 Maximu m 99th Percentile 95th Percentile Median Surface Water   SDWS raw 2 ( ca. 43 sites) 1496 3.320 1.634 0.898 0.118 Surface Water   SDWS finished 2 ( ca. 175 sites) 6774 6.340 1.593 0.761 < 0.1 Ground Water ( shallow)   PGW site averages by date ( 8 sites) 670 Low 4 Low Low Low Ground Water ( shallow)   PGW single cluster basis ( 8 sites) NC 1.400 Low Low Low Ground Water   SGW ( ca. 175 sites) 1983 19.100 1.98 0.177 < 0.1 1 Number of samples represented. NC = Not calculated. 2 Comparisons between raw and finished water concentration distributions should be made with caution since most SDWS sites never had raw water sampled. Statistics based on monitoring for only the last three years of the study ( 1999 to 2001); this is also true for the SGW study. 3 Statistics here are less meaningful for the PGW studies because of the small number of study sites ( 8), the lag time between the start of sampling of ground water after application and breakthrough of any residues into ground water, and the lack of reproduction of long term use patterns in PGW studies ( i. e., generally only a one time application of acetochlor was made during the first growing season of the study). 4 Low = Two few detections to calculate accurately.

Table 30. Chronic Exposure to ESA. Summary presentation of time weighted annualized mean concentrations ( ppb) for the residues of acetochlor ethanesulfonic acid in surface and ground water ( based on maximum TWAM values observed at each site by calendar year).  70

Sample / Study Type N1 (# of sites) Maximu m 99th Percentile 95th Percentile Median Surface Water  SDWS raw 2 111 ( 43) 0.752 0.726 0.525 < 0.200 Surface Water  SDWS finished 2 486 ( 175) 1.008 0.701 0.477 < 0.200 Ground Water ( shallow)  PGW site averages by date 8 ( 8) 3.53 NA 3 NA 1.21 Ground Water ( shallow)   PGW single cluster maximums 58 ( 8) 9.24 NA NA NA Ground Water   SGW 495 ( 176) 12.658 6.713 1.819 < 0.200 1 Number of TWAMs included in statistics; followed by number of study sites represented in parenthesis. Number of sites for SDWS and SGW does not include direct replacement sites. 2 Comparisons between raw and finished water concentration distributions should be made with caution since most SDWS sites never had raw water sampled. Statistics based on monitoring for only the last three years of the study ( 1999 to 2001); this is also true for the SGW study. 3 NA = calculation not appropriate because of the small number of PGW study sites ( 8) and the lack of reproduction of long term use patterns at the study sites. This is also why only the PGW maximum single TWAM at each site was calculated and is a more appropriate endpoint for chronic exposure than multi year means.

Table 31. Chronic Exposure to OXA. Summary presentation of time weighted annualized mean concentrations ( ppb) for the residues of acetochlor oxanilic acid in surface and ground water ( based on maximum TWAM values observed at each site by calendar year). Sample / Study Type N1 (# of sites) Maximu m 99th Percentile 95th Percentile Median Surface Water  SDWS raw 2 111 ( 43) 1.289 1.220 0.766 0.140 Surface Water  SDWS finished 2 486 ( 175) 1.697 0.935 0.628 < 0.100 Ground Water ( shallow)  PGW site averages by date 8 ( 8) Lower 3 NA 4 NA NA Ground Water ( shallow)   PGW single cluster maximums 58 ( 8) Lower NA NA NA Ground Water   SGW 495 ( 176) 5.860 1.852 0.224 < 0.100 1 Number of TWAMs included in statistics; followed by number of study sites represented in parenthesis. Number of sites for SDWS and SGW does not include direct replacement sites. 2 Comparisons between raw and finished water concentration distributions should be made with caution since most SDWS sites never had raw water sampled. Statistics based on monitoring for only the last three years of the study ( 1999 to 2001); this is also true for the SGW study. 3 Lower = Chronic exposure was not calculated for the PGW because the exposure level was clearly lower than for the SDWS or SGW studies and the quantification detection frequency was too low for accurate calculation. 4 NA = calculation not appropriate because of the small number of PGW study sites ( 8) and the lack of reproduction of long term use patterns at the study sites. This is also why only the PGW maximum single TWAM at each site was calculated and is a more appropriate endpoint for chronic exposure than  71

Table 31. Chronic Exposure to OXA. Summary presentation of time weighted annualized mean concentrations ( ppb) for the residues of acetochlor oxanilic acid in surface and ground water ( based on maximum TWAM values observed at each site by calendar year). Sample / Study Type N1 (# of sites) Maximu m 99th Percentile 95th Percentile Median multi year means.

The ARP studies demonstrate that the degradates of acetochlor ( and two other acetanilide herbicides, see the following section) can significantly impact ground and surface waters and that exposure to some mobile and persistent degradates can be significantly higher and more widespread in ground water than the respective parent compounds or than in surface waters. Similar results have been obtained by Kalkhoff et al. ( 1998), Kolpin et al. ( 1996, 1997, and 1998), and Rheineck and Postle ( 2000).

8. OTHER CHEMICALS The ARP collected a wealth of monitoring data for three other pesticides in both the SDWS and SGW studies. Virtually every sample collected in these studies for acetochlor analysis was also analyzed for atrazine, alachlor, and metolachlor. The ethanesulfonic acid and oxanilic acid degradates of both alachlor and metolachlor were also included in the analytical plan.

Sample results for these other analytes are given in Tables 28 to 30 Figures 20 to 22 taken from de Guzman et al. ( 2005), MRID 45722701, and Hackett et al. ( 2005). In general, the detection frequency was atrazine > metolachor > alachlor or acetochlor in both studies; changes in usage pattern over the course of the studies had a marked impact on the detection frequency of alachlor ( declining use over the 7 years of monitoring in the SDWS) and acetochlor ( increasing use over the 7 year monitoring period in the SDWS). Metolachlor degradates were generally detected with greater frequency than alachlor or acetochlor degradates. The sulfonic acid degradates were detected more frequently than the oxanilic acid degradates of the same parent herbicide in ground water; the detection frequency was generally similar for the two degradates in surface waters.

Table 32. Occurrence (%) of TWAMs in Finished Drinking Water at Various Concentrations by Sampling Stratum Percent Occurrence AMC ( µ g L 1 ) Great Continental Smaller Watersheds and Analyte Lakes Rivers 5 10% CI1 11 20% CI > 20% CI Overall  72

> 0.1 Acetochlor 0.0 5.0 2.4 8.5 12.8 8.1 > 1.0 Acetochlor 0.0 0.0 0.0 0.0 0.2 0.1 > 0.5 Ac_ ESA 0.0 0.0 0.9 1.0 10.6 4.9 > 0.5 Ac_ OXA 0.0 0.0 5.2 5.2 15.0 8.5 > 0.1 Alachlor 0.0 0.0 3.1 5.8 2.6 2.9 > 1.0 Alachlor 0.0 0.0 0.0 0.0 0.0 0.0 > 0.5 AlESA 0.0 0.0 0.9 3.1 1.5 1.4 > 0.5 AlOXA 0.0 0.0 2.6 0.0 0.5 0.8 > 0.1 Atrazine 7.6 70.3 58.7 85.7 86.2 74.4 > 1.0 Atrazine 0.0 0.8 12.5 30.5 25.8 19.8 > 0.1 Metolachlor 0.0 36.4 25.4 44.0 44.7 37.1 > 1.0 Metolachlor 0.0 0.0 1.7 2.7 3.0 2.2 > 0.5 MeESA 0.0 5.8 15.5 29.9 45.9 29.4 > 0.5 MeOXA 0.0 0.0 6.0 20.6 16.4 12.4 1 CI = Corn production intensity in the watershed.

Figure 20. Box plot of annualized mean concentrations ( AMCs) of parent herbicides in finished drinking water from the SDWS study ( Hackett et al., 2005).  73

Figure 21. Co occurrence of ( a) sulfonic acid ( ESA) degradate residues and ( b) oxanilic acid ( OXA) degradate residues for acetochlor, alachlor, and metolachlor in the SGW study. Values reflect the number of SGW wells with observed residues ( Minimum detection limit was 0.2 ppb for the sulfonic acid degradates and 0.1 ppb for the oxanilic acid degradates). No ESA soil degradate residues were observed in 49 of the 182 wells and no OXA soil degradate residues were observed in 110 of the 182 wells. Source: de Guzman et al. ( 2005).

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

0 0.2 0.4 0.6 0.8 1 Nationwide Use on Corn ( kg/ ha) Detection Frequency Atrazine Metolachlor Acetochlor Alachlor 1995 1995 1995 1995 2001 2001 2001 2001 Figure 22. . Frequency of drinking water detections by year for parent herbicides as a function of use ( relative use on the x axis)   SDWS study.  74

Table 33. Summary of the Distribution of Degradate Residues for ARP SGW Analytes   2001 Data only.

The values represent the numbers of samples with residues fitting the specified criteria.

Compound Not Detected OR " NR" LOD to 0.499 0.50 to 0.999 ppb 1.0 to 1.999 ppb 2.0 to 9.999 ppb >= 10.0 ppb Total Ac_ ESA 475 56 31 32 28 2 624 AlESA 435 48 45 40 51 5 624 MeESA 311 74 59 55 114 11 624 Ac_ OXA 578 27 6 7 5 1 624 AlOXA 599 18 0 3 4 0 624 MeOXA 506 80 16 10 12 0 624 Ac_ ESA = Acetochlor sulfonic acid Ac_ OXA = Acetochlor oxanilic acid AlESA = Alachlor sulfonic acid AlOXA = Alachlor oxanilic acid MeESA = Metolachlor sulfonic acid MeOXA = Metolachlor oxanilic acid OXA Limit of Detection ( LOD) = 0.10 ppb ESA Limit of Detection ( LOD) = 0.20 ppb Limit of Quantitation ( LOQ) = 0.50 ppb.

Source: MRID 45722701.

Table 34. Summary of the Distribution of Parent Residues for ARP SGW Analytes   2001 data only.

Compound Not Detected ( ND) OR " NR" 0.03 to 0.049 ppb 0.05 to 0.099 ppb 0.10 to 0.249 ppb 0.25 to 0.499 ppb 0.50 to 4.999 ppb >= 5.0 ppb Total Acetochlor 611 3 2 2 3 3 0 624 Alachlor 623 ND 1 0 0 0 0 624 Atrazine 400 38 58 87 28 13 0 624 Metolachlor 611 1 9 3 0 0 0 624 The values represent the numbers of samples with residues fitting the specified criteria.

Limit of Detection ( LOD) = 0.03 ppb for acetochlor, atrazine, and metolachlor.

Alachlor LOD = 0.05 ppb Limit of Quantitation ( LOQ) = 0.05 ppb.

Source: MRID 45722701.  75

9. CONCLUSIONS This analysis characterized the overall detection of acetochlor and its degradates ( ethanesulfonic acid, and oxanilic acid) with an emphasis on parent acetochlor, given its inclusion by the Office of Pesticide Programs in the residues of concern for human exposure.

9.1. Parent Acetochlor Surface water sources are the driver for exposure to parent acetochlor ( Table 1). There is a potential for underestimation of chronic exposure to acetochlor parent from the ARP study because of:   The lack of raw water analyses at most of the sites makes it difficult to extrapolate the results to estimate exposure in additional ( or new) use areas or to predict the impact of changes in the type of water treatment used on exposure levels.   Some areas with fewer CWS that utilize surface waters present ( or use a mixture of sources) were largely unrepresented in the SDWS Available data indicate that water treatment involving the use of activated carbon may reduce exposure by close to 50% on average; limitations on the SDWS data preclude generalizing this as a predictable effect of water treatment. Others have found that GAC treatment may remove 60 to 90% of the acetochlor parent residues originally present in the raw water ( Bloomquist et al., 2001; Coupe et al., 2004).

The ARP data that are available match raw and finished water samples at selected sites only in the sense that they were taken on the same day. Matching of the same volume of water is difficult, but the publications by Blomquist et al. and Coupe et al. provide a description of an attempt to match such samples as closely as possible. the ARP SDWS dataset did not measure samples in intake water from those systems using other types of water treatment, and most of the highest concentrations observed in the SDWS study occurred in finished ( not raw) samples.

Maximum acetochlor instantaneous concentrations, 95th percentiles, and time weighted annualized means in the SDWS were all observed from the Gillespie, Illinois reservoir ( Table 9). The highest acetochlor parent concentrations observed in the ARP monitoring program were 1.428 for chronic exposure ( Table 1) and the highest finished water acute exposure was 18.21 ( Table 9); all these values were from the surface water monitoring program ( SDWS study). Significantly higher concentrations were observed in the NAWQA monitoring program ( Table 14), although these sites did not necessarily represent source water for drinking.

Geographic analysis of the SDWS monitoring locations, CWS intake locations, and acetochlor usage intensity indicates that the SDWS monitoring program may have missed some of the watersheds in the Midwestern US with the highest acetochlor usage intensities over the monitoring program. A lower rate of utilization and lower overall numbers of surface water  76

sources by drinking water facilities in these high acetochlor use regions appears to be a factor in the paucity of sites in these regions that were eventually selected for monitoring in the SDWS ( probably a sample selection algorithm that placed greater emphasis on a preference for geographic diversity in the higher corn density strata could have prevented this). The lack of monitoring in some of the high acetochlor use areas is especially problematic for the SDWS where the lack of sampling of raw ( pre facility treatment) water at most locations makes it difficult to isolate the effects of site specific usage and vulnerability factors and water treatment processes on the observed residue levels.

We conclude therefore, there is a potential that exposure could be somewhat higher in areas other than those monitored if treatment systems at the locality do not remove a significant portion of the acetochlor residues, utilization of surface water sources for drinking water increases in some high use areas, and/ or the usage of acetochlor expands in some areas through changing patterns of corn production or registration and use of acetochlor on additional crop sites. Further analysis may be needed if the reported acetochlor concentrations are within a factor of 3 of levels of concern for drinking water.

Besides the above described difficulties in isolating the effects of water treatment on observed residues from the ARP SDWS study, a number of uncertainties must be recognized when interpreting this exposure assessment. These include the following:

° The surface drinking water supply ( SDWS) and state ground water ( SGW) monitoring programs were designed to focus on areas of high acetochlor use. The monitoring does not cover the entire geographic distribution of acetochlor use. Conclusions drawn in this report apply only to those areas monitored by the ARP and it may not be possible to generalize to all acetochlor usage areas. Additional data analysis and modeling would be needed to expand this exposure assessment to cover the unmonitored areas.

° County level sales data submitted separately by members of the ARP from 1994  2003 is arguably some of the most extensive data available as a close approximation of acetochlor usage across the US. As such, it has been incorporated in this exposure assessment as a surrogate for acetochlor use in the mapping and statistical analyses. It is assumed that acetochlor sold in an individual county is, in general, also applied in the same county and in the same watershed. However, the exposure characterization recognizes that inter county as well as inter watershed transfer of acetochlor does occur in some cases.

° Acute exposure in this risk assessment is defined as the overall maximum observed concentration at a site. The actual peak concentration, however, may have occurred between sampling times. Thus, the maximum observed concentrations reported in this study may underestimate the true maximum acute exposure.

9.2. Acetochlor Degradates The Health Effects Division of OPP has determined that the available toxicological data indicates that degradates do not have similar toxicological endpoints to parent acetochlor nor to  77

each other. Consequently, the emphasis on our analysis has been on separate examination of exposure levels for each of these compounds.

The highest monitored values for acetochlor ESA were:

Acute exposure: 20.0 ppb ESA in a sample from one of the approximately 175 SGW study sites.

Chronic exposure: 12.7 ppb ESA TWAM from one of the SGW study sites.

The highest monitored values for acetochlor OXA were:

Acute exposure: 19.1 ppb OXA in a sample from a shallow well from one of the SGW study sites.

Chronic exposure: 5.9 ppb OXA TWAM from a shallow well from one of the SGW study sites.

Acetochlor degradates ethanesulfonic acid ( ESA) and oxanilic acid ( OXA) were detected more frequently and at higher concentrations than the parent acetochlor in ground water; chronic levels of the degradates in surface water tended to be similar to that of parent ( Compare Table 1 with Table 27, Table 30, and Table 31). Peak levels of degradates in surface waters were generally lower or similar to peak levels of parent acetochlor ( Compare Table 11 and Table 12 with Table 28 and Table 29).  78

10. REFERENCES Blomquist, J. D., Denis, J. M., Cowles, J. P., Hetrick, J. A., Jones, R. D., and Birchfield, N. B. 2001. Pesticides in Selected Water Supply Reservoirs and Finished Drinking Water, 1999 2000: Summary of Results from a Pilot Monitoring Program, Open File Report 01 456, U. S. Geological Survey.

Coupe, R. H, and Blomquist, J. D., 2004. Water soluble pesticides in finished water of community water supplies. Journal American Water Works Association, v. 96( 10): 56 68.

De Guzman, N. P, Hendley, P., Gustafson, D. I., van Wesenbeeck, I., Klein, A. J., Fuhrman, J. D., Travis, K., Simmons, N. D., Teskey, W. E., and R. B. Durham. 2005. The Acetochlor State Ground water Monitoring Program. J. Env. Qual. 34: 793 803.

Hackett, A. G., J. D. Fuhrman, and C. Van Bellinghen. 2003. Chloroacetanilide Herbicides. p. 344 388. In P. W. Lee ( ed.) Handbook of Residue Analytical Methods for Agrochemicals, Volume 1, John Wiley & Sons, West Sussex, UK.

Hackett, A. G., Gustafson, D. I., Moran, S. J., Hendley, P., van Wesenbeeck, I., Simmons, N. D., Klein, A. J., Kronenberg, J. M., Fuhrman, J. D., Hanzas, J., Healy, D., and C. T. Stone. 2005. The Acetochlor Surface Drinking Water Monitoring Program. J. Env. Qual. 34: 877 889.

Lavy, T. L. Mattice, J. D. Massey, J. H. Skulman, B. W. Senseman, S. A. Gbur, E. E Jr., Barrett, M. R. Long term in situ leaching and degradation of six herbicides aged in subsoils. Journal of Environmental Quality. v 25 n 6 Nov Dec 1996. p1268 1279.

Mills, M. S., I. R. Hill, A. C. Newcombe, N. D. Simmons, P. C. Vaughan, and A. A. Verity. 2001. Quantification of acetochlor degradation in the unsaturated zone using two novel in situ field techniques: comparisons with laboratory generated data and implications for groundwater risk assessments. Pest Management Science 57( 4): 351 359.

Newcombe, A. C., Gustafson, D. I., Fuhrman, J. D., van Wesenbeeck, I. J., Simmons, N. D., Klein, A. J., Travis, K. Z., and K. J. Harradine. 2004. The Acetochlor Prospective Ground Water Monitoring Program. J. Env. Qual. 34: 1004 1015.

USEPA. 1994. Acetochlor Registration Agreement and Addendums. http:// www. epa. gov/ oppefed1/ aceto/ regagree. htm U. S. Environmental Protection Agency. 1998. Reregistration Eligibility Decision ( RED): Alachlor. No. 738 R 98 020. Available online at: http:// www. epa. gov/ oppsrrd1/ REDs/ 0063. pdf.

USEPA. 2004. Office of Pesticide Programs. Acetochlor Homepage: Desk Statement, Talking Points, and Usage Targets and Results. http:// www. epa. gov/ oppefed1/ aceto/ index. htm ( visited: 3 August 2004).  79

USGS. 2004. Development and Application of Watershed Regressions for Pesticides ( WARP) for Estimating Atrazine Concentration Distributions in Streams. Water Resources Investigations Report 03 4047. 68 pp.

11. BIBLIOGRAPHY EPA Reviews and Documents Environmental Fate and Ground Water Branch, OPP, EPA. 1993. Review of environmental fate data submitted in support of Section 3 registration. Memorandum dated June 17, 1993 from Paul Mastradone to J. Miller / J. Mays, PM 23, Registration Division. DP Barcode D168599.

Environmental Fate and Ground Water Branch, OPP, EPA. 1993. Review of 162 1, 162 2 and 164 1 studies for registration; also request for extension of EUP on corn. Memorandum dated December 6, 1993 from Akiva Abramovitch to Robert Taylor, PM 25, Registration Division. DP Barcodes D174457, D182799, D187736, D193537, and D194713.

Environmental Fate and Ground Water Branch, OPP, EPA. 1994. Review of 162 1, 162 2 and 164 1 studies for registration; response to registrant's response to 12/ 6/ 93 review. Memorandum dated January 26, 1994 from Akiva Abramovitch to Robert Taylor, PM 25, Registration Division. DP Barcode D197606.

Environmental Fate and Effects Division, OPP, EPA. 2001. Drinking water assessment for atrazine and various chloro triazine and hydroxyl triazine degradates. Memorandum dated January 23, 2001 from Henry Nelson, James Lin and Mary Frankenberry to Pam Noyes, Triazine Manager, Special Review and Reregistration Division. Available on the web at: http:// www. epa. gov/ oppsrrd1/ reregistration/ atrazine/ drinkingwater. pdf ( visited November 11, 2004).

Health Effects Division, OPP, EPA. 2004. Acetochlor. Report of the Metabolism Assessment Review Committee. Health Effects Division internal memorandum dated August 31, 2004 from Albert Protzel to Yan Donovan, Executive Secretary, Metabolism Assessment Review Committee.

Official Submissions to EPA ARP error correction comments on the 12/ 31/ 04 actochlor drinking water assessment: ARP 2005 ( MRID unknown). Response to Preliminary Human Health Risk Assessment for the Tolerance Reassessment Progress and Risk Management Decision ( TRED) for Acetochlor.  80

Letter dated 9/ 13/ 05 from Dawn Fee White ( ARP) to Rosanna Louie ( EPA). DP Barcode 293329.

ARP Submissions  Section 1: ENVIRONMENTAL FATE STUDIES ( Grouped by study type.)

Guideline: 161 1 Hydrolysis  MRID: 00064805 Campbell, D. H.; Hamilton, D. E.; Kloek, J. A.; et al. ( 1980). The Environmental Studies of Acetochlor: Report No. MSL 1255. Final rept. ( Unpublished study received Dec 12, 1980 under 524 EX 56; submitted by Monsanto Co., Washington, D. C.; CDL: 099814 C)

MRID: 41565144 Myers, H. ( 1989) ICIA 5676: Hydrolysis Studies: Lab Project Number: WRC 88 70. Unpublished study prepared by ICI Americas Inc. 17 p.

MRID: 41613301 Howe, R. ( 1990) New Information on MON 4660 Environmental Fate Studies, Addendum to MSL 4383: Lab Project Number: RD 1010. Un Published study prepared by Monsanto Agricultural Co. 49 p.

Guideline: 161 2 Photodegradation water  MRID: 00131388 Letendre, L.; Klemm, G.; Singh, H. ( 1982) The Environmental Photo chemistry of Acetochlor: Project No. 7827; Report No. MSL 2748. ( Unpublished study received Sep 22, 1983 under 524 348; submit ted by Monsanto Co., Washington, DC; 071961 C)

MRID: 41565145 Chotalia, R.; Weissler, M. ( 1989) Acetochlor: Photolysis in Aqueous Solution at pH 7: Lab Project Number: 88JH448: RJ0726B. Unpub lished study prepared by ICI Agrochemicals. 63 p.

Guideline: 161 3 Photodegradation soil  MRID: 00131388 Letendre, L.; Klemm, G.; Singh, H. ( 1982) The Environmental Photo chemistry of Acetochlor: Project No. 7827; Report No. MSL 2748. ( Unpublished study received Sep 22, 1983 under 524 348; submit ted by Monsanto Co., Washington, DC; 071961 C)

MRID: 00160233 Groya, F., comp. ( 1986) Information to Support the Registration of Harness Herbicide ( Acetochlor): Response to Review of Environmental Fate Data: Special Report MSL 5570. Unpublished compilation prepared by Monsanto Agricultural Co. 15 p.  81

MRID: 41565146 Hawkins, D.; Kirkpatrick, D.; Dean, G. ( 1990) The Photodegradation of carbon 14| Acetochlor on Soil: Lab Project Number: HRC/ ISN 187/ 891375. Unpublished study prepared by Huntingdon Research Centre Ltd. 62 p.

Guideline: 162 1 Aerobic soil metabolism  MRID: 00064805 Campbell, D. H.; Hamilton, D. E.; Kloek, J. A.; et al. ( 1980) The Environmental Studies of Acetochlor: Report No. MSL 1255. Final rept. ( Unpublished study received Dec 12, 1980 under 524 EX 56; submitted by Monsanto Co., Washington, D. C.; CDL: 099814 C)

MRID: 41565147 Hawkins, D.; Kirkpatrick, D.; Dean, G. ( 1989) The Metabolism of carbon 14 Acetochlor in Silty Clay Loam Soil under Aerobic Conditions: Lab Project Number: HRC/ STR 19/ 881751. Unpublished prepared by Huntingdon Research Centre Ltd. 84 p.

MRID: 41613301 Howe, R. ( 1990) New Information on MON 4660 Environmental Fate Studies, Addendum to MSL 4383: Lab Project Number: RD 1010. Un Published study prepared by Monsanto Agricultural Co. 49 p.

MRID: 41963316 Hawkins, D.; Kirkpatrick, D.; Dean, G.; et al. ( 1991). The Metabolism of Carbon 14 Acetochlor in Silty Clay Loam Soil under Aerobic Conditions: Lab Project Number: HRC/ STR 19/ 901756. Unpublished study prepared by Huntingdon Research Centre Ltd. 29 p.

MRID: 41963317 Hawkins, D.; Kirkpatrick, D.; Dean, G. ( 1991) The Metabolism of carbon 14| Acetochlor in Sandy Loam Soil under Aerobic Conditions: Lab Project Number: HRC/ ISN 185/ 90535. Unpublished study prepared by Huntingdon Research Centre Ltd. 57 p.

Guideline: 162 2 Anaerobic soil metabolism  MRID: 41338501 Campbell, D.; Hamilton, D. ( 1989) Anaerobic Soil Metabolism Studies of Acetochlor: Final Report: Study No. MSL 9183; RD 971; Project No. 207300. Unpublished study prepared by Monsanto Agricultural Co. 52 p.

MRID: 41565148 Hawkins, D.; Kirkpatrick, D.; Dean, G. ( 1989) The Metabolism of carbon 14| Acetochlor in Sandy Loam Soil under Anaerobic Conditions: Lab Project Number: HRC/ ISN 184/ 89619. Unpublished study prepared by Huntingdon Research Centre Ltd. 45 p.

MRID: 41613301  82

Howe, R. ( 1990) New Information on MON 4660 Environmental Fate Studies, Addendum to MSL 4383: Lab Project Number: RD 1010. Un Published study prepared by Monsanto Agricultural Co. 49 p.

MRID: 41963318 Hawkins, D.; Kirkpatrick, D.; Dean, G.; et al. ( 1991) The Metabolism of Carbon 14 Acetochlor in Sandy Loam Soil Under Aerobic Conditions: Part II: Lab Project Number: HRC/ ISN 184/ 89619. Un published study prepared by Huntingdon Research Centre Ltd. 24 p.

Guideline: 163 1 Leaching / adsorption / desorption  MRID: 00031329 Jordan, G. L.; Harvey, R. G. ( 1978) Environmental Factors and Soil Relationships Influencing the Activity of Acetanilide Herbicides. Doctoral Thesis, Univ. of Wisconsin, Dept. of Agronomy. ( pp. 22 58 only; unpublished study received May 3, 1979 under 43142 1; submitted by Boots Hercules Agrochemicals Co., Wilmington, Del.; CDL: 098274 I)

MRID: 00064805 Campbell, D. H.; Hamilton, D. E.; Kloek, J. A.; et al. ( 1980) The Environmental Studies of Acetochlor: Report No. MSL 1255. Final rept. ( Unpublished study received Dec 12, 1980 under 524 EX 56; submitted by Monsanto Co., Washington, D. C.; CDL: 099814 C)

MRID: 41338502 Campbell, D.; Hamilton, D. ( 1989) Leaching and Adsorption/ Desorption Studies of Acetochlor: Final Report: Study No. MSL 9184; RD 971; Project No. 207300. Unpublished study prepared by Monsanto Agricultural Co. 72 p.

MRID: 41565149 Hartfield, R. ( 1990) Acetochlor and its Two Major Metabolites: Adsorption/ Desorption in Soil: Lab Project Number: 89JH375: RJ0837B. Unpublished study prepared by ICI Agrochemicals. 44 p.

MRID: 41613301 Howe, R. ( 1990) New Information on MON 4660 Environmental Fate Studies, Addendum to MSL 4383: Lab Project Number: RD 1010. Un Published study prepared by Monsanto Agricultural Co. 49 p.

MRID: 41963319 Robbins, A.; Lane, M. ( 1991) Acetochlor: Adsorption and Desorption of 5676/ 48, the Thioacetic Acid Sulphoxide Metabolite, in Soil: Lab Project Number: RJ0887B. Unpublished study prepared by ICI Agrochemicals. 45 p.

Guideline: 164 1 Terrestrial field dissipation  MRID: 00064803  83

Horner, L. M.; Purdum, W. R.; Campbell, D. H. ( 1980) Residues of Acetochlor in Field Soils following Preemergent Treatment with Acetochlor Alone or in Tank Mix Combinations with Atrazine, Dyanap, Linuron and Metribuzin: Report No. MSL 1260. Interim rept. ( Unpublished study received Dec 12, 1980 under 524 EX 56; submitted by Monsanto Co., Washington, D. C.; CDL: 099814 A)

MRID: 00130838 Monsanto Co. ( 1983) Residue Studies on Harness: Executive Summary. ( Compilation; unpublished study received Sep 22, 1983 under 524 348; CDL: 071958 B; 071959; 071960)

MRID: 40811901 Lottman, C. ( 1988) Residues of Acetochlor in Field Soils following Preemergent Treatment with Acetochlor Alone or in Tank Mix Combinations with Atrazine, Dyanap, Linuron, and Metribuzin Addendum to MSL 1260 and MSL 1717: Laboratory Project No. MSL 8095: R. D. No. 887. Unpublished study prepared by Monsanto Agricultural Co. 324 p.

MRID: 40811902 Lottman, C. ( 1988) Terrestrial Field Soil Dissipation Study Determination of Acetochlor Residues following Preemergent Application of Top hand Herbicide: Laboratory Project No. MSL 8118: R. D. No. 887. Unpublished study prepared by Monsanto Agricultural Co. 165 p.

MRID: 41089204 Gustafson, D.; Lauer, R.; Horner, L. ( 1988) Terrestrial Field Dissipation of MON 4660 When Applied as MON 8460 to Field Corn: Project No. MSL 8024. Unpublished study prepared by Monsanto Agricultural Co. in cooperation with MetaTrace, Inc. 273 p.

MRID: 41565152 Zilka, S.; Wilson, B.; Hoag, H.; Coombes et al. ( 1990) Acetochlor: Dissipation of Residues in USA Soil under Field Conditions Leland, Mississippi, 1988: Lab Project Number: 5676 88 SD 01. Unpublished study prepared by ICI Agrochemicals. 109 p.

MRID: 41565153 Wilson, B.; Dhillon, P.; Bolygo, E.; et al. ( 1990) Acetochlor: Residues of Oxanilic Acid and Sulphonic Acid Metabolite under Field Conditions in Leland, Mississippi, 1988: Lab Project No: 5676 88 SD 01. Unpublished study prepared by ICI Agrochemicals. 119 p.

MRID: 41592012 Zilka, S.; Wilson, B.; Hoag, R.; et al. ( 1990) Acetochlor: Dissipation of Residues in USA Soil under Field Conditions Champaign, Illinois, 1988: Lab Project Number: 5676 88 SD 01. Unpublished study prepared by ICI Agrochemicals. 113 p.

MRID: 41592013 Wilson, B.; Dhillon, P.; Bolygo, E.; et al. ( 1990) Acetochlor: Residues of Oxanilic Acid and Sulphonic Acid Metabolites in USA under Field Conditions in Champaign, Illinois, 1988: Lab Project Number: 5676 88 SD 01: RJ0850B. Unpublished study prepared by ICI Agrochemicals. 124 p.  84

MRID: 42549907 Lauer, R. ( 1992) Stability of Acetochlor and Its Metabolites in Soil During Frozen Storage: Lab Project Number: MSL 11981. Unpublished study prepared by Monsanto Company. 160 p.

MRID: 42549915 Zilka, S.; Wilson, B.; Hoag, R.; et. al ( 1990) Acetochlor: Dissipation of Residues in USA Soil under Field Conditions Visalia, California, 1988: Lab Project Number: 5676 88 SD 01: RJ0821B. Unpublished study prepared by ICI Agrochemicals. 106 p.

MRID: 42549916 Zilka, S.; Wilson, B.; Hoag, R.; et. al ( 1990) Acetochlor: Dissipation of Residues in USA Soil under Field Conditions Goldsboro, North Carolina, 1988: Lab Project Number: 5676 88 SD 01: RJ0822B. Unpublished study prepared by ICI Agrochemicals. 108 p.

MRID: 42549917 Veal, P.; Grout, S.; Simmons, N. ( 1992) Acetochlor: Residues of Thioacetic Acid Sulphoxide Soil Metabolite under Field Conditions in Champaign, Illinois, 1988: Lab Project Number: 5676 88 SD 01: RJ1031B. Unpublished study prepared by ICI Agrochemicals. 114 p.

MRID: 42549918 Veal, P.; Grout, S.; Simmons, N. ( 1992) Acetochlor: Residues of Thioacetic Acid Sulphoxide Soil Metabolite under Field Conditions in Leland, Mississippi, 1988: Lab Project Number: 5676 88 SD 01: RJ1030B. Unpublished study prepared by ICI Agrochemicals. 110 p.

MRID: 42573402 Lauer, R.; Lau, P. ( 1992) Terrestrial Field Dissipation Study of Acetochlor and Its Soil Metabolites following Preemergent Application of MON 8437 to Field Corn: Lab Project Number: MSL 12089. Unpublished study prepared by Monsanto and Stewart Agricultural Research Services, Inc. 765 p.

MRID: 42831608 Lauer, R.; Gibson, K. ( 1992) Terrestrial Field Dissipation Study of Acetochlor and its Soil Metabolites Following Application of MON 8422 to Field Corn: Lab Project Number: MSL 12166: 90 42 R 2: RD 1130. Unpublished study prepared by Monsanto Co. and Stewart Agricultural Research Services, Inc. 1079 p.

MRID: 42964801 Lauer, R. ( 1992) Stability of Microencapsulated Acetochlor in Soil During Frozen Storage: Lab Project Number: MSL 12219. Unpublished study prepared by Monsanto Company. 76 p.

MRID: 43255008 Wilson, B.; French, D.; Roper, E.; et al. ( 1993) Acetochlor & ( inert ingredient): Dissipation of Residue Levels in Soil from Trials Carried out in the USA During 1992: Lab Project Number: ACET/ 92/ SD/ 03. Unpublished study prepared by Zeneca Agrochemicals Jealotts Hill Research Station. 100 p.  85

Guideline: 164 2 Aquatic field dissipation  MRID: 45449502 Davis, K. ( 2001) Independent Laboratory Validation of " Determination of Soil Degradates of Acetochlor, Alachlor, and Metolachlor in Aqueous Environmental Specimens by LC/ MS/ MS": Lab Project Number: 852 565: 46482: ES ME 0330 02. Unpublished study prepared by ABC Laboratories, Inc. 47 p. { OPPTS 850.7100}

ARP Submissions  Section 2: MONITORING STUDIES   GENERAL MRID: 44002501 Fuhrman, J. ( 1996) Analytical Method Development and First Year Performance: GC/ MS Analytical Methodology to Support the Acetochlor Registration Partnership Surface Water and Ground Water Monitoring Studies: Progress Report: Lab Project Number: MSL 14562: M001/ 1: ACET 95 GW 02. Unpublished study prepared by Ceregen, a Unit of Monsanto Co. 344 p.

MRID: 44529801 Fuhrman, J. ( 1998) GC/ MS Analytical Methodology to Support the Acetochlor Registration Partnership Surface Water and Ground Water Monitoring Studies: Progress Report: Analytical Methodology and Cumulative Interim Performance July 1994 December 1996: Lab Project Number: MSL 15191: 94 27 R 3: ACET 95 GW 02. Unpublished study prepared by Monsanto Co. 502 p. OPP Barcode D245339.

MRID: 45180401 Harradine, K. ( 2000) Acetochlor Registration Partnership: Acetochlor Oxanilic Acid Retrospective Analysis Ground Water Study Analytical Data Summary Report: Lab Project Number: BJK25. Unpublished study prepared by Acetochlor Registration Partnership. 54 p.

ARP Submissions  Section 3: MONITORING STUDIES   SURFACE WATER MRID: 45316601 Hackett, A. ( 2000) ARP SWM Program Analytical Results of the ARP Program Year 2000 through August for Parent Herbicides and Year 2000 Samples Analyzed to Date for Degradates: Lab Project Number: SWM1100. Unpublished study prepared by Monsanto Company. 81 p.

MRID: ? Hackett, A. ( 2000) Surface Drinking Water Monitoring Program for Acetochlor and Other Corn Herbicides: Site Selection and Data Collection. Lab Project Number: SWM1100. Unpublished study prepared by Monsanto Company. 81 p.

MRID: 43924301 Citation: Hackett, A. ( 1996) Surface Drinking Water Monitoring Program for Acetochlor and Other Corn Herbicides: First Year Sampling and Analytical Results: ( Progress Report): Lab  86

ARP Submissions  Section 3: MONITORING STUDIES   SURFACE WATER Project Number: 94 27 R 3: 94 310: MSL 14486. Unpublished study prepared by Ceregen, Unit of Monsanto Co. and Stone Environmental, Inc. 354 p.

MRID: 44299501 Citation: Hackett, A. ( 1997) Surface Drinking Water Monitoring Program for Acetochlor and Other Corn Herbicides: Second Year Sampling and Analytical Results Progress Report: Lab Project Number: 94 27 R 3: 94 310: MSL 15108. Unpublished study prepared by Monsanto Co. and Stone Environmental, Inc. 237 p.

MRID: 44869401 Citation: Hackett, A. ( 1999) Surface Drinking Water Monitoring Program for Acetochlor and Other Corn Herbicides Fourth Year Sampling and Analytical Results: Lab Project Number: MSL 16039: 94 27 R 3: 94 310. Unpublished study prepared by Stone Environmental and Monsanto Company. 238 p.

MRID: 45226301 Hackett, A. ( 2000) Surface Drinking Water Monitoring Program for Acetochlor and Other Corn Herbicides: Fifth Year Sampling and Analytical Results: Lab Project Number: 94 27 R 3: 94 310: MONMO01A 02. Unpublished study prepared by Monsanto Co., Stone Environmental, Inc. and Alta Analytical Lab., Inc. 315 p.

MRID: 45446201 Hackett, A. ( 2001) Surface Drinking Water Monitoring Program for Acetochlor and Other Corn Herbicides. Sixth Year Sampling and Analytical Results: Lab Project Number: 94 27 R 3: 94 310: MSL 17227. Unpublished study prepared by Monsanto Company and Stone Environmental Inc. 320 p.

MRID: 45716901 Citation: Hackett, A. ( 2002) Surface Drinking Water Monitoring Program for Acetochlor and Other Corn Herbicides: Seventh Year Sampling and Analytical Results: Final Report: Lab Project Number: 94 27 R 3: 94 310: MSL 17756. Unpublished study prepared by Monsanto Company and Stone Environmental, Inc. 360 p.

MRID: 44592401 Hackett, A. ( 1998) Surface Drinking Water Monitoring Program for Acetochlor and Other Corn Herbicides: Lab Project Number: 94 27 R 3: 94 310: MSL 15395. Unpublished study prepared by Monsanto Company and Stone Environmental, Inc. 233 p MRID: 45103001 Simmons, N. ( 2000) Occurrence of Acetochlor Soil Degradates in the ARP State Ground and Surface Water Monitoring Programs During 1999: Anticipated Human Exposure to these Materials via Drinking Water: Lab Project Number: BJK23. Unpublished study prepared by Acetochlor Registration Partnership. 30 p.  87

ARP Submissions  Section 3: MONITORING STUDIES   SURFACE WATER MRID: 44590401 Hackett, A. ( 1998) 1997 Annualized Mean Concentrations ( AMC's) and 1997 and Early 1998 Analytical Results: Surface Water Monitoring Program: Monsanto Study No. 94 27 R 3. Unpublished study prepared by Monsanto Co. and the Acetochlor Registration Partnership. 92 p.

MRID: 45564101 Citation: Hackett, A. ( 2001) ARP Surface Water Monitoring ( SWM) Program Analytical Results of the ARP Program Year 2001 Through August for Parent Herbicides and Degradates: Lab Project Number: SWM1201: 94 27 R 3. Unpublished study prepared by Monsanto Company. 104 p.

MRID: 45714801 Citation: Hackett, A. ( 2002) ARP Surface Water Monitoring Program Annualized Means and Analytical Results for the ARP Program in 2001: Lab Project Number: SWM0702: 852 573: 94 27 R 3. Unpublished study prepared by Monsanto Company. 173 p.

ARP Submissions  Section 4: MONITORING STUDIES   PROSPECTIVE GROUND WATER MRID: 43944901 Dwinell, S.; French, D.; Moore, W. et al. ( 1996) Acetochlor: USA Prospective Ground Water Study Series I ( WI & OH): 1st Interim Report December 1995: Lab Project Number: ACET 95 PG 02: 3277: RR 95 094B. Unpublished study prepared by Zeneca Agrochemicals and Levine Fricke, Inc. 404 p.

MRID: 44193101 Dwinell, S.; French, D.; Moore, W. et al. ( 1996) Acetochlor: USA Prospective Ground Water Study Series 1 ( WI & OH): 2nd Interim Report December, 1996: Lab Project Number: ACET 95 PG 02: 3277: RR 96 081 B INT. Unpublished study prepared by Zeneca Agrochemicals and Levine. Fricke. Recon Inc. 512 p.

MRID: 44221601 Freiwald, R.; Friet, S.; Harradine, K. ( 1997) Acetochlor: USA Prospective Ground Water Study Series II ( MN, NE, IA, and IN): 1st Interim Report February, 1997: Lab Project Number: ACET 96 PG 05: 3277: RR 96 104B INT. Unpublished study prepared by Zeneca Agrochemicals and Levine. Fricke. Recon Inc. 762 p.\

MRID: 44402801 Durham, R.; Harradine, K.; Johnson, R. et al. ( 1997) Acetochlor: USA Prospective Ground Water Study Series I ( WI & OH): Final Report October, 1997: Lab Project Number: ACET  88

ARP Submissions  Section 4: MONITORING STUDIES   PROSPECTIVE GROUND WATER 95 PG 02: 3277: RR 96 081B FIN. Unpublished study prepared by Zeneca Agrochemicals ( Jealott's Hill Research Station) and Levine. Fricke. Recon Inc. 578 p.

MRID: 44402801 Durham, R.; Harradine, K.; Johnson, R. et al. ( 1997) Acetochlor: USA Prospective Ground Water Study Series I ( WI & OH): Final Report October, 1997: Lab Project Number: ACET 95 PG 02: 3277: RR 96 081B FIN. Unpublished study prepared by Zeneca Agrochemicals ( Jealott's Hill Research Station) and Levine. Fricke. Recon Inc. 578 p.

MRID: 44492401 Bedosky, S.; Harradine, K.; Johnson, R.; et al. ( 1997) Acetochlor: USA Prospective Ground Water Study Series III ( PA) 1st Interim Report November, 1997: Lab Project Number: RR 97 061B INT1: 3277: ACET 96 PG 06. Unpublished study prepared by Zeneca Agrochemicals and Levine Fricke Recon Inc. 287 p.

MRID: 44523101 Durham, R.; Freiwald, R.; Friet, S. et al. ( 1998) Acetochlor: USA Prospective Ground Water Study Series II ( MN, NE, IA and IN) 2nd Interim Report March, 1998: Lab Project Number: ACET 96 PG 05: 3277: RR 96 104B INT2. Unpublished study prepared by Zeneca Ag Products and Levine. Fricke. Recon Inc. 1152 p.

MRID: 44752801 Bedosky, S.; Harradine, K.; Newcombe, A. ( 1999) Acetochlor: USA Prospective Ground Water Study Series III ( PA) 2nd Interim Report January, 1999: Lab Project Number: 3277: ACET 96 PG 06: RR97 061BINT2. Unpublished study prepared by Zeneca Ag Products and Levine. Fricke Inc. 412 p.

MRID: 44757501 Newcombe, A. ( 1999) Acetochlor Registration Partnership: Acetochlor: USA Prospective Ground Water Study Series I ( WI & OH): Analytical Data Summary Report: ( Pre Application to 40 Months): Lab Project Number: PGWQ13A. Unpublished study prepared by Acetochlor Registration Partnership. 62 p.

MRID: 44875701 Bedosky, S.; Harradine, K.; Robinson, G. et al. ( 1999) ACETOCHLOR: USA Prospective Ground Water Study Series IV ( DE) 1st Interim Report March, 1999: Lab Project Number: RR 99 005B INT1: ACET 98 PG 07: 3277. Unpublished study prepared by ZENECA Agrochemicals and Levine. Fricke Inc. 301 p.

MRID: 45216501 Bedosky, S.; Robinson, G.; Harradine, K. et al. ( 2000) ACETOCHLOR: USA Prospective Ground Water Study Series IV ( DE) 2nd Interim Report September, 2000: Lab Project Number: 3277: ACET 98 PG 07: RR 99 005B INT2. Unpublished study prepared by ZENECA  89

ARP Submissions  Section 4: MONITORING STUDIES   PROSPECTIVE GROUND WATER Agrochemicals and LFR Levine Fricke Inc. 470 p.

MRID: 46138601 Newcombe, A.; Gustafson, D.; van Wesenbeeck, I. ( 2003) Acetochlor Registration Partnership Minnesota Prospective Groundwater Trial  Final Report. Project Number: ACET/ 96/ PG/ 05, 004/ 03277/ 88/ 435, 852/ 594. Unpublished study prepared by Monsanto Company, Zeneca Agrochemicals, and Covance Laboratories, Ltd. 238 p.

MRID: 46204201 Newcombe, A.; Gustafson, D.; van Wesenbeeck, I. ( 2004) Acetochlor Registration Partnership Indiana Prospective Groundwater Trial  Final Report. Project Number: ARP # ACET/ 96/ PG/ 05, Levine Fricke # 004/ 03277/ 88/ 433. Unpublished study prepared by Monsanto Company, Zeneca Agrochemicals, and Covance Laboratories, Ltd. 258 p.

MRID: 45181901; Amendment ( New MRID?) Newcombe, A.; Gustafson, D.; van Wesenbeeck, I. ( 2004) Acetochlor Registration Partnership Ohio Prospective Groundwater Trial   Amended Final Report. Project Number: ARP # ACET/ 95/ PG/ 02, Levine Fricke # 004/ 03277/ 88/ 437. Unpublished study prepared by Monsanto Company, Zeneca Agrochemicals, and Natural Resource Management, Ltd. 244 p.

MRID: 46290201; Amendment ( New MRID, replaces # 45181901) Newcombe, A.; Gustafson, D.; van Wesenbeeck, I. ( 2004) Acetochlor Registration Partnership Wisconsin Prospective Groundwater Trial   Amended Final Report. Project Number: ARP # ACET/ 95/ PG/ 02, Levine Fricke # 004/ 03277/ 88/ 436. Unpublished study prepared by Monsanto Company, Zeneca Agrochemicals, and Natural Resource Management, Ltd. 239 p.

MRID: 46188701 Newcombe, A.; Gustafson, D.; van Wesenbeeck, I. ( 2004) Acetochlor Registration Partnership Minnesota Prospective Groundwater Trial   Amended Final Report. Project Number: ARP # ACET/ 96/ PG/ 05, Levine Fricke # 004/ 03277/ 88/ 435. Unpublished study prepared by Monsanto Company, Zeneca Agrochemicals, and Covance Laboratories, Ltd. 255 p. DP # 301795.

MRID: 46274201 Newcombe, A.; Gustafson, D.; van Wesenbeeck, I. ( 2004) Acetochlor Registration Partnership Delaware Prospective Groundwater Trial   Final Report ( dated 5/ 5/ 2004). Project Number: ARP # ACET/ 98/ PG/ 07, Levine Fricke # 004/ 03277/ 88/ 432. Unpublished study prepared by Monsanto Company, Zeneca Agrochemicals, and Natural Resource Management, Ltd. 306 p. DP # 304735.

MRID: 46232801 Newcombe, A.; Gustafson, D.; van Wesenbeeck, I. ( 2004) Acetochlor Registration Partnership Pennsylvania Prospective Groundwater Trial   Final Report ( dated 3/ 18/ 2004). Project Number: ARP # ACET/ 96/ PG/ 06, Levine Fricke # 004/ 03277/ 88/ 431. Unpublished study prepared by  90

ARP Submissions  Section 4: MONITORING STUDIES   PROSPECTIVE GROUND WATER Monsanto Company, Zeneca Agrochemicals, and Covance Laboratories, Ltd. 306 p. DP # 302847.

ARP Submissions  Section 5: MONITORING STUDIES   STATE GROUND WATER MRID: 43899601 Hendley, P. ( 1995) State Ground Water Monitoring Program for Acetochlor and Other Corn Herbicides Part 1: Site Selection and Site Details: Lab Project Number: ACET 94 GW 01: RR 95 087B: GWMSIT05. DOC. Unpublished study prepared by Zeneca Ag Products and Levine Fricke, Inc. 3217 p.

MRID: ? Hendley, P. ( 1996) State Ground Water Monitoring Program for Acetochlor and Other Corn Herbicides Part 2. 1995 Progress Report: Lab Project Number: Zeneca # ACET 95 GW 02; Levine Fricke # 3276.101; Report # RR 96 019B. Unpublished study prepared by Zeneca Ag Products; Monsanto; Levine, Fricke. 261 p.

MRID: 44422501 Hendley, P. ( 1997) State Ground Water Monitoring Program for Acetochlor and Other Corn Herbicides Part 3. 1996 Progress Report: Lab Project Number: ACET 95 GW 02: 3276.101: RR 97 034B. Unpublished study prepared by Zeneca Ag Products; Monsanto; Levine, Fricke, Recon Inc. 138 p. OPP DP Barcode D252465.

MRID: 44599201 Hendley, P. ( 1998) State Ground Water Monitoring Program for Acetochlor and other Corn Herbicides Part 4. 1997 Progress Report: Lab Project Number: RR 98 026B: ACET 95 GW 02: 3276. 101. Unpublished study prepared by Zeneca Ag Products and Monsanto. 137 p.

MRID: 44948701 De Guzman, N. ( 1999) State Groundwater Monitoring Program for Acetochlor and Other Corn Herbicides Part 5: 1998 Progress Report: Lab Project Number: ACET 95 GW 02: 3276.101: RR 99 031B. Unpublished study prepared by Zeneca Ag Products; Monsanto and LFR Levine Fricke. 143 p.

MRID: 45208501 De Guzman, N. ( 2000) State Ground Water Monitoring Program for Acetochlor and Other Corn Herbicides Part 6: Lab Project Number: ACET 95 GW 02: 3276.101: RR 00 100B. Unpublished study prepared by Levine Fricke, Zeneca, and Alta Analytical Laboratory, Inc. 191 p.

MRID: 45449601  91

ARP Submissions  Section 5: MONITORING STUDIES   STATE GROUND WATER De Guzman, N. ( 2001) State Ground Water Monitoring Program for Acetochlor and Other Corn Herbicides Part 7: 2000 Progress Report: Lab Project Number: 852 562: ACET 95 GW 02: 3276.101. Unpublished study prepared by LFR Levine Fricke, Monsanto, and Dow AgroSciences LLC. 15 p.

MRID: 45722701 de Guzman, N.; Fuhrman, J.; Gustafson, D.; et al. ( 2002) State Ground Water Monitoring Program For Acetochlor and Other Corn Herbicides Part 8. 2001 Progress Report: Lab Project Number: ACET 95 GW 02: 3276.101: ARP GWM 01. Unpublished study prepared by LFR Levine Fricke ( LFR), Dow AgroSciences LLC and Monsanto. 158 p.

MRID: 45728401 van Wesenbeeck, I.; De Guzman, N.; Fuhrman, J.; et al. ( 2002) State Ground Water Monitoring Program for Acetochlor and Other Corn Herbicides Part 9: Final Study Report: Lab Project Number: ARP GWM 02: 852 577: ACET 95 GW 02. Unpublished study prepared by LFR Levine Fricke and Monsanto. 121 p.

MRID: 45730201 De Guzman, N.; Wesenbeeck, I. ( 2002) State Ground Water Monitoring Program for Acetochlor and Other Corn Herbicides Part 10 Amendment to the Final Study Report: Lab Project Number: ACET 94 GW 01: 3276.101: 852 578. Unpublished study prepared by LFR Levine Fricke, Monsanto and Dow AgroSciences LLC. 300 p.

Barcodes of actions completed with this review: D245339 D249062 D257732 D257889 D257961 D257976: D257982 D258421 D258783 D258856 D260167 D260372 D260831 D260917 D262987 D263614 D265250 D265265 D265617 D265628 D266400 D268225 D269431 D269432 D269661 D269664 D269888 D271012 D271883 D272255 D272343 D272347 D275586 D275593 D275890 D278534 D278837 D279225 D279306 D280431 D280479 D284563 D284868 D284868 D284868 D288177 D301788 D301823 D305544 D275887 Pertinent Outside Literature  92

Barbash, J. E., G. P. Thelin, D. W. Kolpin, and R. J. Gilliom. 1999. Distribution of major herbicides in ground water of the United States. Water Resource Investigations Rep. 98 4245. Available online at http:// ca. water. usgs. gov/ pnsp/ rep/ wrir984245/ ( verified 7 Jan. 2003). U. S. Geol. Survey, Sacramento, CA.

Battaglin, W. A., and D. A. Goolsby. 1999. Are shifts in herbicide use reflected in concentration changes in midwestern rivers. Environ. Sci. Technol. 33: 2917  2925.

Coupe, R. H. and J. D. Blomquist. 2004. Water soluble pesticides in finished water of community water supplies. Journal AWWA 96: 56 68.

Kalkhoff, S. J. 1994. National Water Quality Assessment Program  Eastern Iowa basins. Factsheet FS 94 031. Available online at http:// iowa. usgs. gov/ nawqa/ factsheets/ factsheet. html ( verified 7Jan. 2003). U. S. Geol. Survey, Iowa City, IA.

Kalkhoff, S. J., D. W. Kolpin, and E. M. Thurman. 1998. Degradation of chloroacetanilide herbicides: The prevalence of sulfonic and oxanilic acid degradation products in Iowa ground and surface waters. Environ. Sci. Technol. 32: 1738  1740.

Kalkhoff, S.; Kolpin, D.; Thurman, E. et al. ( 1998) Degradation of Chloroacetanilide Herbicides: The Prevalence of Sulfonic and Oxanilic Acid Metabolites in Iowa Ground and Surface Waters. Unpublished study prepared by U. S. Geological Survey. 13 p. EPA MRID: 44512601.

Kolpin, D. W., S. J. Kalkhoff, D. A. Goolsby, D. A. Sneck Fahrer, and E. M. Thurman. 1997. Occurrence of selected herbicides and herbicide degradation products in Iowa's ground water, 1995. Ground Water 35: 679  688.

Kolpin, D. W., E. M. Thurman, and D. A. Goolsby. 1996. Occurrence of selected pesticides and their metabolites in near surface aquifers of the midwestern United States. Environ. Sci. Technol. 30: 335  340.

Kolpin, D. W., E. M. Thurman, and S. M. Linhart. 1998. The environmental occurrence of herbicides: The importance of degradation products in ground water. Arch. Environ. Contam. Toxicol. 35: 385  390.

Rheineck, B. and J. Postle. 2000. Chloroacetanilide Herbicide Metabolites in Wisconsin Groundwater. Wisconsin Department of Agriculture, Trade and Consumer Protection, ARM Division   Groundwater Unit; ARM publication 82.  93

12. APPENDICES APPENDIX 12.1. Chemical Names and Structures Table A 1. Chemical names and structures of acetochlor and its degradates discussed in this exposure assessment.

N CH 3 Cl O O CH 3 C H 3 Acetochlor 2' Ethyl 6' methyl N( ethoxymethyl) 2 chloroacetanilide N CH 3 SO 3 H O O CH 3 C H 3 Acetochlor ethanesulfonic acid 2[( 2 ethyl 6 methylphenyl)( ethoxymethyl) amino] 2 oxoethanesulfonic acid N CH 3 O CH 3 C H 3 O O H O Acetochlor oxanilic acid 2[( 2 ethyl 6 methylphenyl)( ethoxymethyl) amino] 2 oxoacetic acid]  94  95

Table A 2. Structures of the chloroacetanilide herbicides and their major degradates ( Source: ARP pre publication journal article).

Both the SDWS and the SGW studies conducted by the ARP simultaneously monitored for each of these three parent compounds ( plus the corn herbicide atrazine) during the full 7 years of monitoring and for each of the degradation products listed during the last 3 years of monitoring. R2 R1 N R3 O R4 R1 R2 R3 R4 Common Name Abbr. Chemical Name ( CAS) LOD/ LOQ ( µ g L 1) CAS Number CH3 CH3CH2 CH2OCH2CH3 CH2Cl acetochlor Acet 2 chloro N( ethoxymethyl) N( 2 ethyl 6

methylphenyl) acetamide 0.03/ 0.05 34256 82 1 CH3CH2 CH3CH2 CH2OCH3 CH2Cl alachlor Alac 2 chloro N( 2,6 diethylphenyl) N

( methoxymethyl) acetamide 0.05/ 0.05 15972 60 8 CH3 CH3CH2 CH( CH3) CH2OCH3 CH2Cl metolachlor Meto 2 chloro N( 2 ethyl 6 methylphenyl) N( 2

methoxy 1 methylethyl) acetamide 0.03/ 0.05 51218 45 2 CH3 CH3CH2 CH2OCH2CH3 CH2SO3H acetochlor sulfonic acid Ac_ ESA 2[( ethoxymethyl)( 2 ethyl 6 methyl phenyl) amino] 2 oxoethanesulfonic acid 0.20/ 0.50 187022 11 3 CH3 CH3CH2 CH2OCH2CH3 CO2H acetochlor oxanilic acid Ac_ OXA 2[( ethoxymethyl)( 2 ethyl 6

methylphenyl) amino] oxoacetic acid 0.10/ 0.50 194992 44 4 CH3CH2 CH3CH2 CH2OCH3 CH2SO3H alachlor sulfonic acid AlESA [ 2( 2,6 diethylphenyl)( methoxymethyl) amino] 2

oxoethanesulfonic acid 0.20/ 0.50 142363 53 9 CH3CH2 CH3CH2 CH2OCH3 CO2H alachlor oxanilic acid AlOXA [ 2( 2,6 diethylphenyl)( methoxymethyl) amino] 2

oxoacetic acid 0.10/ 0.50 171262 17 2 CH3 CH3CH2 CH( CH3) CH2OCH3 CH2SO3H metolachlor sulfonic acid MeESA 2[( 2 ethyl 6 methylphenyl)( 2 methoxy 1

methylethyl) amino] 2 oxoethane sulfonic acid 0.20/ 0.50 171118 09 5 CH3 CH3CH2 CH( CH3) CH2OCH3 CO2H metolachlor oxanilic acid MeOXA [( 2 ethyl 6 methylphenyl)( 2 methoxy 1

methylethyl) amino] oxoacetic acid 0.10/ 0.50 152019 73 3 Atrazine, which is not a chloroacetanilide herbicide, was also monitored in this study, and is denoted by the abbreviation: Atra. Its chemical name is 6 chloro N ethyl N'( 1 methylethyl) 1,3,5 triazine

2,4 diamine, and its CAS number is 1912 24 9. Its LOD and LOQ were 0.03 and 0.05 µ g L 1, respectively.  96

APPENDIX 12.2. Acetochlor Registration Agreement   Cancellation / Mitigation Endpoints The following text is excerpted from the registration agreement ( section numbering retained from the agreement):

Excerpt1, Regarding Ground Water Detections:

5.1.3. Response to Ground Water Detections <IP_ADDRESS> Investigation of Cause of Detections Any information pertaining to detection of acetochlor and any degradates of toxicological concern which become known to the ARP, Monsanto, Zeneca or their agents will be reported to EPA within 15 days of the date such information becomes known to the ARP, Monsanto, Zeneca, or their agents. The ARP may respond to any detections of acetochlor or its degradates of toxicological concern reported by investigators, using confirmed analytical methods, by sending a qualified third party representative to investigate the incident. The investigation shall be completed within 60 days of receipt of the report and the results reported to EPA within 30 days of completion of the investigation, unless the ARP and EPA agree to extend those deadlines. The investigation may include any additional sampling useful in determining if the detection is due to a point source or intentional contamination. The EPA shall consider the results of any such investigation in determining whether a reported and investigated detection will be considered a " detection" for the purpose of establishing a pattern of movement, or the need for additional mitigation, or for triggering suspension or cancellation under this Section 5.1.3.

<IP_ADDRESS> Exposure Reduction For detections verified by the ARP's GC/ MS method ( at ARP's expense), occurring at a level at or above 1.0 ppb in rural drinking water wells, the ARP will offer without conditions a Well Assistance Program to compensate rural well owners by paying for the cost of drilling the new well, or installing and maintaining filters, or connecting to public water supplies, and other appropriate measures. The ARP will unconditionally pay for all costs associated with this remediation up to $ 5,000 per well ( in 1994 dollars). All private rural drinking water wells and community drinking water supply wells in rural areas are eligible for the ARP well assistance program.

Public wells in rural areas which have verified detections ( using the ARP's GC MS method) at ARP's expense of acetochlor at a level at or above 1.0 ppb, that are not associated with product mishandling will be, at ARP's expense, remediated to provide drinking water below a detection limit of 0.10 ppb.

<IP_ADDRESS>. Detection Criteria The data from either the PGW or other sampling/ monitoring programs may indicate a pattern of movement of acetochlor or degradates of toxicological concern toward ground water, as a result of use according to label directions or in accordance with widespread and commonly recognized practice. At present, the ARP is not aware of any degradates of toxicological concern. If, in the future, EPA determines there are degradates of toxicological concern, the detection concentrations noted below will be reviewed and will be revised, if appropriate, based upon the toxicologic effect of the degradate. A pattern of movement is defined as being:  97

  detections of acetochlor or degradates of toxicological concern confirmed by the approved and validated GC MS method, and   IN THE PGW STUDIES. Detections of acetochlor or degradates of toxicological concern that are greater than or equal to 0.10 ppb in ground water which are consistent with recharge as measured with tracers and/ or suction lysimeters; OR Detections of acetochlor or degradates of toxicologic concern at a concentration greater than or equal to 1.0 ppb in soil water collected by suction lysimeters at a depth of 9 feet below the land surface. Such soil water detections must be consistent with the movement of soil water as determined by conservative tracers, and consistent with detections in the three and six foot lysimeters in that cluster. Lysimeter samples from the same depth will be composited to ensure adequate sample size ( for the purpose of analysis) when necessary; or   IN THE STATE MONITORING PROGRAMS. For reports of detections of acetochlor or degradates of toxicological concern in the state monitoring programs described in section 5.1.2, a detection greater than or equal to a concentration of 0.10 ppb in ground water subsequently detected at greater than or equal to 0.10 ppb in two follow up samples collected monthly over a period of six months; or   OTHER MONITORING STUDIES ( outside of the PGW study or State Monitoring Programs ( defined in section 5.1.2)). For reports of any other detections of acetochlor, a detection greater than or equal to a concentration of 0.20 ppb in ground water, subsequently detected at greater than or equal to 0.20 ppb in two or more follow up samples collected monthly over a period of six months.

If the ARP does not take appropriate steps to secure follow up sampling, the initial report of the detection shall be treated as sufficient to define a pattern of movement. The determination of what constitutes appropriate steps to be taken is a " reserved issue" subject to the provisions of Section 7A.

<IP_ADDRESS>. Additional Mitigation Measures If EPA determines that a pattern of movement, as defined in <IP_ADDRESS>. has occurred from use in accordance with label directions or in accordance with widespread and commonly recognized practice, then the ARP, in conjunction with EPA, will determine whether the movement is limited to a geographical area or soil type. In that case, the ARP will revise the acetochlor label to include geographic or additional soil type label restrictions.

<IP_ADDRESS>. Automatic Suspension If EPA determines that a pattern of movement toward ground water as defined in <IP_ADDRESS>., above has occurred arising from use in accordance with label directions or in accordance with widespread and commonly recognized practice, and if within 30 days EPA and the ARP cannot agree on an immediate mitigation option, the registration shall be automatically suspended on a geographic basis. This suspension will terminate if EPA determines that the ARP has taken adequate steps to implement appropriate mitigation measures. The determination of appropriate mitigation options shall be governed by the provisions of Section 7.

<IP_ADDRESS>. Cancellation   GW Scenario 1  98

For the PGW studies, if EPA determines that out of the 8 sites, 4 sites in a variety of geographic, and climatic conditions under both vulnerable and general use conditions, ( as determined by EPA) in corn growing areas indicate a pattern of movement of acetochlor toward ground water, as defined in <IP_ADDRESS>. from use in accordance with label directions or in accordance with widespread and commonly recognized practice, registration shall be automatically canceled. The sites at which a pattern of movement occurs shall represent a range of vulnerable and general use soil textures consistent with labeled use.

  GW Scenario 2 For monitoring programs outside the PGW studies, the registration of acetochlor will be automatically canceled if EPA determines that either of the criteria specified below have been met. All detections shall be verified by the ARP's GC MS method at the ARP's expense.

o Criterion 1:

Detections occur in 20 or more wells included in the State Monitoring Program at or above 0.10 ppb followed by two subsequent detections of at least 0.10 ppb in monthly sampling of each of those wells, conducted over a period of six months.

o Criterion 2:

Detections occur in 150 or more individual wells at or above 0.20 ppb, followed   by two subsequent detections of at least 0.20 ppb in monthly sampling of each of those wells, conducted over a period of six months across a wide variety of geographic, soil, and climatic conditions in corn growing area.

  GW Scenario 3 For monitoring programs outside the PGW studies, the registration of acetochlor will be automatically canceled if EPA determines that detections occur in twenty ( 20) or more wells across a wide variety of geographic, soil, and climatic conditions in corn growing areas at a concentration of at least 1.0 ppb, followed by two subsequent detections of at least 1.0 ppb in monthly sampling of each of those wells, conducted over a period of six months. All detections shall be verified by the ARP's GC MS method at the ARP's expense.

An initial detection shall be treated as sufficient to meet these cancellation criteria if the ARP has failed to take timely and appropriate steps to secure follow up samples.

If EPA determines at any time that mitigation measures have been or will be undertaken which are likely to be effective, the Agency may treat, for a period of up to 18 months, some or all detections within the area subject to such mitigation measures ( mitigation area) as insufficient to meet the cancellation criteria in section <IP_ADDRESS>. No later than 18 months after such mitigation measures have been initiated, EPA shall make a final determination whether the mitigation measures have been or are likely to be effective. During this time, the ARP may investigate whether such mitigation measures have been, or are likely to be, effective. The EPA shall notify the ARP 60 days prior to making its determination, and shall consider the results of any such investigation, if timely received, in making that determination. If EPA's final determination is that the mitigation measures have not been or are not likely to be successful, all detections within the mitigation area shall be subject to the provisions of sections <IP_ADDRESS>., <IP_ADDRESS>., and <IP_ADDRESS>. If EPA's final determination is that the mitigation measures have been or are likely to be successful,  99

some or all detections within the mitigation area may be designated by EPA as insufficient to meet the cancellation provisions of Section <IP_ADDRESS>. Such final determination will be consistent, to the extent feasible, with relevant existing policies and procedures.

Point source contamination detections shall be treated as sufficient to meet these cancellation criteria unless EPA determines that such contamination: ( i) does not result from use in accordance with label directions or widespread and commonly recognized practice, or ( ii) results from use in accordance with label directions or in accordance with widespread and commonly recognized practice, but that the general cause of the contamination can be mitigated with product stewardship, label language or repair/ replacement of damaged or inadequately installed wells.

5.2. State Management Plans If at any time after the registration EPA decides to nominate acetochlor for inclusion in State Management Plans, the ARP will not file any objection to such inclusion, nor will it challenge such action in any court or administrative forum.

5.3. Continued Stewardship Regardless of whether the data indicate any pattern of movement toward groundwater, the ARP will continue its product stewardship commitment and cooperate with the Agency to develop and implement additional product stewardship measures considered appropriate.

Excerpt 2, Regarding Surface Water Detections:

6.2 Response to Surface Water Detections The ARP agrees in principle to provisions relating to surface water, which include a sampling program, investigation of the source of surface water detections, and mitigation measures. The elements of the response to surface water detections will parallel those described in Section 5 for ground water protection.

6.2.1 Investigation of Cause of Detections The ARP may respond to any detections of acetochlor or degradates of toxicological concern, using confirmed analytical methods, by sending a qualified third party representative to investigate the incident. The investigation shall be completed within 60 days of the incident becoming known to the ARP and the results reported to EPA within 30 days of completion of the investigation, unless the ARP and EPA agree to extend those deadlines. The investigation may include any additional sampling useful in determining if the detection is due to a point source or intentional contamination. The EPA shall consider the results of any such investigation in determining whether a reported and investigated detection will be considered a " detection" for the purpose of establishing the need for mitigation or for triggering cancellation under Section 6.2.2.

6.2.2 Mitigation and Cancellation At present, the ARP is not aware of any degradates of toxicological concern. If, in the future, EPA determines there are degradates of toxicological concern, the detection concentrations noted below will be reviewed and will be revised, if appropriate, based upon the toxicologic effect of the degradate.

  SW Scenario I:  100

If one ( 1) community water supply system, that derives its water primarily from surface water, detects an annual time weighted mean concentration of 2.0 ppb, acetochlor, then either;

o The use of acetochlor in the related watershed will be prohibited. Such prohibition will be implemented by means of amendment of the acetochlor registration to prohibit sale, distribution, and use in the specified watershed. The timing, content, and implementation of such restriction shall be governed by the provisions of Section 7; or o The ARP will absorb 100% of costs required to restore the community water supply system to compliance. If EPA determines that the ARP has failed to meet this obligation, it may cancel the registration without opportunity for hearing.   SW Scenario II:

If EPA determines that two ( 2) large ( serving 100,000 people) community water supply systems, or ten ( 10) community water supply systems of any size across a wide variety of corn growing, soil, and climatic have an annual time weighted mean concentration of 2.0 ppb or are otherwise determined to be out of compliance based on Office of Water criteria, the registration will be automatically canceled.

If any community water supply system that derives its water primarily from surface water detects a single peak concentration of 8.0 ppb of acetochlor, the ARP will make biweekly sampling of that water system throughout the following 12 months to determine whether the 2.0 ppb annual time weighted mean concentration has been exceeded.  101

APPENDIX 12.3. Acetochlor Usage   Detailed Summary CONFIDENTIAL BUSINESS INFORMATION, NOT INCLUDED HERE  102

APPENDIX 12.4. Locations of Monitoring Sites for the ARP SDWS Study ( Acetochlor Surface Drinking Water Supply Study)

P1 ( primary) Community Water Systems only CITY STATE SUPPLY SYSTEM NAME TYPE WATERSHE D AREA ( acres) WATERSHED RUNOFF RATING WATERS HED %

CORN INTENSIT Y STATISTICA L STRATUM ACTIVATE CARBON Treatment ?

Corning IA Lake Binder Lake 2126 15.3 23.0 > 20% CI YES Des Moines IA Raccoon River and Infiltration Galleries River 2304810 31.1 39.4 > 20% CI YES Iowa City IA Iowa River River 2099081 30.6 40.3 > 20% CI YES Milford IA West Lake Okoboji Lake 14866 22.9 32.6 > 20% CI YES Montezuma IA Diamond Lake Reservoir 2724 31.8 33.3 > 20% CI YES Mount Pleasant IA Skunk River River 2599367 15.6 34.2 > 20% CI YES Okoboji IA West Okoboji Lake Lake 14866 22.9 32.6 > 20% CI NO Ottumwa IA Des Moines River River 8569564 31.7 35.5 > 20% CI YES Panora IA Middle Racoon River River 265272 32.5 41.1 > 20% CI NO Spirit Lake IA Spirit Lake Lake 43135 25.0 36.2 > 20% CI NO Winterset IA Cedar Lake Reservoir 10443 35.5 21.7 > 20% CI YES Altamont IL Altamont New Reservoir Reservoir 521 26.7 28.5 > 20% CI YES Blandinsville IL LaHarpe Creek River 8779 33.7 35.5 > 20% CI NO Breese IL Shoal Creek River 480358 35.7 25.2 > 20% CI YES Carlinville IL Carlinville Lake I Reservoir 15706 28.8 25.0 > 20% CI YES Carthage IL Carthage Lake Reservoir 1756 33.6 28.4 > 20% CI YES Charleston IL Lake Charleston Reservoir 1198 28.7 34.4 > 20% CI YES Clay City IL Little Wabash River River 518175 36.3 26.9 > 20% CI YES Decatur IL Lake Decatur Reservoir 602057 30.1 41.5 > 20% CI YES Elgin IL Fox River River 953176 23.4 20.3 > 20% CI YES Fairfield IL Little Wabash River River 1169567 35.4 25.0 > 20% CI YES Flora IL Little Wabash River River 491311 36.5 27.3 > 20% CI YES Georgetown IL Little Vermillion River River 106395 35.7 39.5 > 20% CI YES  103

P1 ( primary) Community Water Systems only CITY STATE SUPPLY SYSTEM NAME TYPE WATERSHE D AREA ( acres) WATERSHED RUNOFF RATING WATERS HED %

CORN INTENSIT Y STATISTICA L STRATUM ACTIVATE CARBON Treatment ?

Gillespie IL Old Gillespie Lake Reservoir 2966 30.3 25.0 > 20% CI YES Greenfield IL Greenfield Lake Reservoir 724 28.1 29.1 > 20% CI YES Hudson IL Lake Bloomington Reservoir 41942 28.7 44.4 > 20% CI YES Kankakee IL Kankakee River River 2952111 27.1 37.4 > 20% CI YES Litchfield IL Lake Lou Yeager Reservoir 69219 23.3 30.1 > 20% CI YES Mascoutah IL Kaskaskia River River 2844480 29.7 26.3 > 20% CI YES Mattoon IL Lake Paradise Reservoir 11916 29.3 34.5 > 20% CI YES Nashville IL City of Nashville Reservoir Reservoir 1013 21.1 23.1 > 20% CI YES Neoga IL Lake Mattoon Reservoir 34849 32.7 33.5 > 20% CI YES New Athens IL Kaskaskia River River 3274132 30.6 25.4 > 20% CI YES New Berlin IL Spring Creek River 16852 34.1 35.2 > 20% CI YES Oakland IL Lake Oakland Reservoir 6909 26.5 39.7 > 20% CI YES Olney IL East Fork Lake Reservoir 6644 28.1 28.8 > 20% CI YES Palmyra IL Palmyra Modesto Lake Reservoir 826 40.0 25.0 > 20% CI YES Pana IL Lake Pana Reservoir 4545 33.8 32.3 > 20% CI YES Paris IL Twin Lakes Reservoir 11733 30.3 38.7 > 20% CI YES Pittsfield IL Lake Pittsfield Reservoir 6971 40.6 22.6 > 20% CI NO Shipman IL Shipman Reservoir Reservoir 427 28.6 25.0 > 20% CI NO Sparta IL South City Lake Reservoir 480 32.0 15.2 > 20% CI YES Springfield IL Lake Springfield Lake 162178 29.7 34.9 > 20% CI YES West Salem IL West Salem Reservior &

shale pit Reservoir 614 27.2 26.1 > 20% CI NO White Hall IL White Hall Reservoir Reservoir 613 29.8 29.1 > 20% CI YES Ferdinand IN Old Lake ( No. 1) Reservoir 105 29.7 26.2 > 20% CI NO Holland IN New Holland Lake Reservoir 348 27.4 26.2 > 20% CI YES Kokomo IN Wildcat Creek River 121637 37.4 38.0 > 20% CI YES Logansport IN Eel River River 524144 24.9 28.3 > 20% CI NO Mitchell IN East Fork of the White River River 2470938 39.5 26.9 > 20% CI YES North Vernon IN Vernon Fork of Muscatatuck River River 68241 26.3 21.0 > 20% CI YES  104

P1 ( primary) Community Water Systems only CITY STATE SUPPLY SYSTEM NAME TYPE WATERSHE D AREA ( acres) WATERSHED RUNOFF RATING WATERS HED %

CORN INTENSIT Y STATISTICA L STRATUM ACTIVATE CARBON Treatment ?

Oakland City IN Old Lake Lake 83 31.9 33.8 > 20% CI YES Richmond IN Middle Fork Reservoir Lake 30825 25.3 27.2 > 20% CI YES Santa Claus IN Christmas Lake Reservoir 1583 37.4 21.8 > 20% CI NO Seymour IN East Fork of the White River River 1516709 33.2 33.8 > 20% CI YES Speedway IN Big Eagle Creek River 119080 29.2 26.8 > 20% CI YES Warsaw IN Center Lake Reservoir 444 20.3 30.3 > 20% CI NO Westport IN Sand Creek River 60170 30.2 43.1 > 20% CI YES Concordia MO Edwin A. Pape Lake Reservoir 5507 23.8 20.6 > 20% CI YES Higginsville MO Higginsville City Lake Reservoir 3547 23.5 20.6 > 20% CI YES Plattsmouth NE Beaver Lake Reservoir 7397 33.5 26.1 > 20% CI YES Archbold OH Tiffin River River 208202 29.8 23.9 > 20% CI YES Attica OH Honey Creek River 46710 28.9 24.2 > 20% CI YES Bowling Green OH Maumee River River 3977343 26.0 23.1 > 20% CI YES Cedarville OH Massies Creek River 31764 30.4 27.2 > 20% CI NO Celina OH Grand Lake St Marys Reservoir 72549 32.8 30.9 > 20% CI NO Columbus OH Scioto River River 665366 27.4 21.4 > 20% CI YES Defiance OH Maumee River River 1395515 26.8 21.5 > 20% CI YES Delta OH Bad Creek River 22000 22.0 33.6 > 20% CI YES Lima OH Auglaize River River 131174 25.2 24.3 > 20% CI NO McClure OH Maumee River River 3777748 26.0 23.0 > 20% CI YES McComb OH Rader Creek River 668 30.3 23.4 > 20% CI YES Metamora OH Ten Mile Creek River 3174 31.5 32.4 > 20% CI YES Ottawa OH Blanchard River River 394516 27.2 23.5 > 20% CI YES Upper Sandusky OH Upper Sandusky Reservoir Reservoir 894 29.7 23.8 > 20% CI YES Van Wert OH Town Creek River 16385 33.3 29.2 > 20% CI NO West Milton OH Stillwater River River 427302 28.9 28.3 > 20% CI NO Wilmington OH Caesar's Creek Lake Reservoir 147651 36.9 27.1 > 20% CI YES Denver PA Cocalico Creek River 12201 30.6 26.4 > 20% CI NO  105

P1 ( primary) Community Water Systems only CITY STATE SUPPLY SYSTEM NAME TYPE WATERSHE D AREA ( acres) WATERSHED RUNOFF RATING WATERS HED %

CORN INTENSIT Y STATISTICA L STRATUM ACTIVATE CARBON Treatment ?

New Holland PA New Holland Reservoir Reservoir 704 8.0 27.4 > 20% CI NO Appleton WI Lake Winnebago Lake 3776966 14.6 12.9 > 20% CI YES Menasha WI Lake Winnebago Lake 3776966 14.6 12.9 > 20% CI YES Oshkosh WI Lake Winnebago Lake 3776966 14.6 12.9 > 20% CI YES Bloomfield IA Lake Fisher Reservoir 1458 40.3 13.9 11 20% CI NO Centerville IA Lake Rathbun Reservoir 353792 37.4 13.2 11 20% CI YES Chariton IA Lake Ellis and Lake Morris Reservoir 6453 38.0 10.6 11 20% CI YES Lenox IA Lenox West Lake Reservoir 100 28.4 19.8 11 20% CI NO Mount Ayr IA Loch Ayr Reservoir Reservoir 2563 11.3 13.5 11 20% CI YES Osceola IA West Lake Reservoir 6241 24.2 13.5 11 20% CI YES Centralia IL Raccoon Lake Reservoir 30293 32.0 12.2 11 20% CI YES Coulterville IL Coulterville Lake Reservoir 449 45.3 15.2 11 20% CI YES Farina IL East Fork of Kaskaskia River River 2959 30.6 17.1 11 20% CI YES Highland IL Silver Lake Reservoir 30593 31.0 17.5 11 20% CI YES Salem IL Salem Reservoir Reservoir 2452 29.6 12.2 11 20% CI YES Sorento IL Sorento Lake Reservoir 376 40.2 15.8 11 20% CI NO Austin IN Muscatatuck River River 223967 28.1 11.8 11 20% CI NO Batesville IN Biscoff Reservoir Reservoir 2916 23.1 19.5 11 20% CI NO Fort Wayne IN St. Joseph River River 657980 27.0 18.6 11 20% CI YES Salem IN Lake John Hay Reservoir 5797 27.6 11.9 11 20% CI YES Scottsburg IN Scottsburg Reservoir Reservoir 1977 26.9 11.3 11 20% CI NO Horton KS Delaware River River 91634 33.7 11.5 11 20% CI NO Ewing MO Lewis County Water District Lake Reservoir 684 30.8 14.0 11 20% CI YES Trenton MO Thompson River River 963925 26.8 10.8 11 20% CI YES Wyaconda MO Wyaconda City Lake Reservoir 208 13.0 15.3 11 20% CI YES Galena OH Alum Creek Reservoir Reservoir 82605 23.4 16.5 11 20% CI NO Monroeville OH West Branch Huron River River 138245 29.9 18.7 11 20% CI YES New London OH Buck Creek River 40614 29.1 17.3 11 20% CI NO  106

P1 ( primary) Community Water Systems only CITY STATE SUPPLY SYSTEM NAME TYPE WATERSHE D AREA ( acres) WATERSHED RUNOFF RATING WATERS HED %

CORN INTENSIT Y STATISTICA L STRATUM ACTIVATE CARBON Treatment ?

Paulding OH Flatrock Creek River 109270 36.5 21.4 11 20% CI YES Sunbury OH Big Walnut Creek River 50886 27.8 16.5 11 20% CI YES Westerville OH Alum Creek River 95314 32.1 16.4 11 20% CI YES Willard OH Huron River River 46081 28.2 18.2 11 20% CI NO Williamsburg OH East Fork of the Little Miami River River 149474 35.3 18.1 11 20% CI NO Carlisle PA Conodoguinet Creek River 242629 24.8 12.6 11 20% CI YES Hummelston PA Swatara River River 284337 31.0 12.1 11 20% CI YES Mechanicsburg PA Conodoguinet Creek River 293855 25.4 12.5 11 20% CI YES Norristown PA Schuylkill River River 1133118 28.7 9.2 11 20% CI YES Reading PA Lake Ontellaunee Reservoir 120883 34.1 13.1 11 20% CI YES Newark DE White Clay Creek River 43629 26.8 10.4 5 10% CI YES Wilmington DE Red & White Clay Creek River 100409 27.9 10.6 5 10% CI YES Lamoni IA Home Lake ( Pond) Reservoir 321 31.8 8.7 5 10% CI YES Alto Pass IL Little Cedar Lake Reservoir 19625 17.8 7.3 5 10% CI YES Borden IN Packwood Branch Reservoir Reservoir 1275 28.9 10.8 5 10% CI YES Dubois IN Patoka Lake Reservoir 108655 31.7 8.4 5 10% CI YES Paoli IN Lick Creek River 13424 28.1 8.8 5 10% CI YES St. Meinrad IN Lake Benet Reservoir 135 23.7 4.5 5 10% CI NO Garnett KS Crystal Lake Reservoir 386 35.8 6.1 5 10% CI YES Milford KS Milford Lake Reservoir 15963347 35.3 9.6 5 10% CI YES Richmond KS Richmond City Lake Reservoir 557 29.1 5.1 5 10% CI YES Topeka KS Kansas River River 36446269 28.2 8.8 5 10% CI NO Valley Falls KS Delaware River River 570021 26.1 7.5 5 10% CI NO Westphalia KS Lake ( No Name) Reservoir 1652 42.9 4.8 5 10% CI NO Bel Air MD Winter's Run River 23264 38.5 8.2 5 10% CI YES Elkton MD Big Elk Creek River 39985 30.2 9.7 5 10% CI YES Frederick MD Monocacy River River 456687 30.0 12.0 5 10% CI YES Frederick MD Monocacy River River 456040 27.2 8.9 5 10% CI YES  107

P1 ( primary) Community Water Systems only CITY STATE SUPPLY SYSTEM NAME TYPE WATERSHE D AREA ( acres) WATERSHED RUNOFF RATING WATERS HED %

CORN INTENSIT Y STATISTICA L STRATUM ACTIVATE CARBON Treatment ?

Havre de Grace MD Susquehanna River River 17629428 15.0 5.5 5 10% CI YES Silver Spring MD Howard Duckett Reservoir ( Rocky Gorge Re Reservoir 85109 31.9 5.6 5 10% CI YES Moorhead MN Red River River 4309787 20.0 10.8 5 10% CI YES Armstrong MO Armstrong City Lake Reservoir 342 28.6 10.4 5 10% CI YES Bethany MO Old City Lake Reservoir 191 39.7 10.2 5 10% CI NO Butler MO Butler City Lake Reservoir 1965 31.5 6.6 5 10% CI YES Cameron MO Reservoirs # 1 # 2 and # 3 Reservoir 3274 26.7 8.2 5 10% CI YES Edina MO New Lake Reservoir 781 38.5 8.6 5 10% CI YES Freeman MO South Grand River River 63850 36.2 5.6 5 10% CI NO Gallatin MO Lake Viking Reservoir 9049 32.3 7.1 5 10% CI YES Garden City MO Lake 1 Reservoir 455 35.2 5.8 5 10% CI YES Gentry MO Middle Fork Water Co. Lake Reservoir 4233 29.7 9.5 5 10% CI NO Labelle MO LaBelle City Lake # 1 Reservoir 140 34.2 14.0 5 10% CI YES Lancaster MO North Lake Reservoir 728 29.5 6.1 5 10% CI NO Marceline MO New Marceline Reservoir Reservoir 2455 24.3 12.6 5 10% CI YES Monroe City MO South Lake Reservoir 668 25.5 6.2 5 10% CI YES Perryville MO Saline Creek River 36335 26.3 8.6 5 10% CI NO Shelbina MO Shelbina Lake Reservoir 1521 43.0 8.8 5 10% CI YES Smithville MO Smithville Lake Reservoir 133182 23.5 8.8 5 10% CI YES Vandalia MO Vandalia Reservoir Reservoir 3654 28.1 11.8 5 10% CI YES Alliance OH Deer Creek Lake Reservoir 162028 21.9 8.5 5 10% CI YES Glouster OH Burr Oak Lake Reservoir 20596 27.0 3.7 5 10% CI YES Somerset OH Somerset Reservoir Reservoir 572 31.9 8.3 5 10% CI YES Wellsville OH Little Yellow Creek River 10832 29.5 9.2 5 10% CI YES Beavertown PA PL 638 Reservoir 3339 8.4 10.4 5 10% CI NO Phoenixville PA Schuylkill River River 771279 28.7 10.4 5 10% CI NO West Chester PA East Branch of Brandywine River River 72185 28.3 10.3 5 10% CI YES Davenport IA Mississippi River River 56626192 11.1 15.9 Cntl. River YES  108

P1 ( primary) Community Water Systems only CITY STATE SUPPLY SYSTEM NAME TYPE WATERSHE D AREA ( acres) WATERSHED RUNOFF RATING WATERS HED %

CORN INTENSIT Y STATISTICA L STRATUM ACTIVATE CARBON Treatment ?

Moline IL Mississippi River River 56626192 11.1 15.9 Cntl. River YES Rock Island IL Mississippi River River 56626192 11.1 15.9 Cntl. River YES Shipman IL Mississippi River River 115258084 23.1 24.2 Cntl. River YES Evansville IN Ohio River River 68358056 21.8 5.6 Cntl. River YES Mount Vernon IN Ohio River River 68778138 21.8 5.7 Cntl. River YES Atchison KS Missouri River River 266847707 10.1 5.1 Cntl. River NO Kansas City KS Missouri River River 268749082 10.2 5.1 Cntl. River YES Leavenworth KS Missouri River River 267061176 10.1 5.1 Cntl. River YES Minneapolis MN Mississippi River River 12527540 14.6 7.5 Cntl. River YES St. Cloud MN Mississippi River River 8774874 12.6 4.0 Cntl. River YES Jefferson City MO Missouri River River 319081997 13.1 5.7 Cntl. River YES Louisiana MO Mississippi River River 90230044 17.9 22.1 Cntl. River YES St. Louis MO Mississippi River River 443533492 15.3 10.1 Cntl. River YES St. Louis MO Missouri River River 332845687 29.2 5.6 Cntl. River YES Blair NE Missouri River River 203739516 9.3 3.3 Cntl. River YES Hartington NE Lewis & Clark Lake ( Missouri River) Reservoir 177705449 7.4 0.8 Cntl. River NO Omaha NE Missouri River River 204687766 9.4 3.5 Cntl. River YES East Liverpool OH Ohio River River 14999469 17.7 2.5 Cntl. River YES Chicago IL Lake Michigan Lake 28845270 14.4 8.9 Great Lakes YES Michigan City IN Lake Michigan Lake 28845270 14.4 8.9 Great Lakes YES Beaver Bay MN Lake Superior Lake 10719768 7.2 0.0 Great Lakes NO Cleveland OH Lake Erie Lake 63168475 14.2 8.2 Great Lakes YES Willoughby OH Lake Erie Lake 63168475 14.2 8.2 Great Lakes YES Cudahy WI Lake Michigan Lake 28845270 14.4 8.9 Great Lakes YES  109

P1 ( primary) Community Water Systems only CITY STATE SUPPLY SYSTEM NAME TYPE WATERSHE D AREA ( acres) WATERSHED RUNOFF RATING WATERS HED %

CORN INTENSIT Y STATISTICA L STRATUM ACTIVATE CARBON Treatment ?

Oak Creek WI Lake Michigan Lake 28845270 14.4 8.9 Great Lakes YES Port Washington WI Lake Michigan Lake 28845270 14.4 8.9 Great Lakes YES P1 ( primary) Community Water Systems only Site ID ( ARP) CITY STATE SUPPLY SYSTEM NAME TYPE WATERSH ED AREA ( acres) WATERSHED RUNOFF RATING WATERS HED %

CORN INTENSIT Y STATISTICAL STRATUM ACTIVATE CARBON Treatment ?

651

NE DE Newark DE White Clay Creek River 43629 NA 10.4 5 10% CI 652

WI DE Wilmington DE Red & White Clay Creek River 100409 NA 10.6 5 10% CI 544

BL IA Bloomfield IA Lake Fisher Reservoir 1458 390 mg 13.9 11 20% CI 577

RA IA Centerville IA Lake Rathbun Reservoir 353792 Unknown 13.2 11 20% CI 548

CH IA Chariton IA Lake Ellis and Lake Morris Reservoir 6453 598 mg 10.6 11 20% CI 553

CO IA Corning IA Lake Binder Lake 2126 85 acres 23 > 20% CI 556

DA IA Davenport IA Mississippi River River 56626192 NA 15.9 Continental Rivers 557

DM IA Des Moines IA Raccoon River and Infiltration Galleries River 2304810 Unknown 39.4 > 20% CI 562 ICIA Iowa City IA Iowa River River 2099081 NA 40.3 > 20% CI 565

LA IA Lamoni IA Home Lake ( Pond) Reservoir 321 65 mg 8.7 5 10% CI 566

LE IA Lenox IA Lenox West Lake Reservoir 100 13 acres 19.8 11 20% CI  110

569 MIIA Milford IA West Lake Okoboji Lake 14866 NA 32.6 > 20% CI 570

MO IA Montezuma IA Diamond Lake Reservoir 2724 125 acres 250 mg 33.3 > 20% CI 571

MA IA Mount Ayr IA Loch Ayr Reservoir Reservoir 2563 78 acres 13.5 11 20% CI 572

MP IA Mount Pleasant IA Skunk River River 2599367 NA 34.2 > 20% CI 547

CW IA Okoboji IA West Okoboji Lake Lake 14866 NA 32.6 > 20% CI 574

OS IA Osceola IA West Lake Reservoir 6241 300 acres 13.5 11 20% CI 575

OT IA Ottumwa IA Des Moines River River 8569564 NA 35.5 > 20% CI 576

PA IA Panora IA Middle Racoon River River 265272 NA 41.1 > 20% CI 579

SL IA Spirit Lake IA Spirit Lake Lake 43135 6000 acres 36.2 > 20% CI 582

WI IA Winterset IA Cedar Lake Reservoir 10443 886 acreft 21.7 > 20% CI 170

AL IL Altamont IL Altamont New Reservoir Reservoir 521 56 acres 28.5 > 20% CI 261

AP IL Alto Pass IL Little Cedar Lake Reservoir 19625 115 acres 7.3 5 10% CI 601

BL IL Blandinsville IL LaHarpe Creek River 8779 7 acre ft 35.5 > 20% CI 152

BR IL Breese IL Shoal Creek River 480358 15 mg 25.2 > 20% CI 213

CA IL Carlinville IL Carlinville Lake I Reservoir 15706 Unknown 25 > 20% CI 184

CA IL Carthage IL Carthage Lake Reservoir 1756 48 acres 28.4 > 20% CI 225

CE IL Centralia IL Raccoon Lake Reservoir 30293 Unknown 12.2 11 20% CI 155

CH IL Charleston IL Lake Charleston Reservoir 1198 935 mg 34.4 > 20% CI 159

CH IL Chicago IL Lake Michigan Lake 28845270 NA 8.9 Great Lakes 149

CC IL Clay City IL Little Wabash River River 518175 3.4 mg 26.9 > 20% CI  111

242

CO IL Coulterville IL Coulterville Lake Reservoir 449 61 mg 15.2 11 20% CI 212

DE IL Decatur IL Lake Decatur Reservoir 602057 6500 mg 41.5 > 20% CI 197

EL IL Elgin IL Fox River River 953176 NA 20.3 > 20% CI 269

FA IL Fairfield IL Little Wabash River River 1169567 90 mg 25 > 20% CI 172

FA IL Farina IL East Fork of Kaskaskia River River 2959 30 mg 17.1 11 20% CI 150

FL IL Flora IL Little Wabash River River 491311 Unknown 27.3 > 20% CI 263

GO IL Georgetown IL Little Vermillion River River 106395 NA 39.5 > 20% CI 214 GIIL Gillespie IL Old Gillespie Lake Reservoir 2966 250 mg 25 > 20% CI 182

GE IL Greenfield IL Greenfield Lake Reservoir 724 50 acres 9 ft deep 29.1 > 20% CI 222 HIIL Highland IL Silver Lake Reservoir 30593 550 acres 17.5 11 20% CI 603

BL IL Hudson IL Lake Bloomington Reservoir 41942 7380 acre ft 44.4 > 20% CI 198

KA IL Kankakee IL Kankakee River River 2952111 1.25 mg 37.4 > 20% CI 233 LIIL Litchfield IL Lake Lou Yeager Reservoir 69219 1500 acres 30.1 > 20% CI 608

SU IL Mascoutah IL Kaskaskia River River 2844480 Unknown 26.3 > 20% CI 157

MA IL Mattoon IL Lake Paradise Reservoir 11916 900 mg 34.5 > 20% CI 248

MO IL Moline IL Mississippi River River 56626192 NA 15.9 Continental Rivers 268

NA IL Nashville IL City of Nashville Reservoir Reservoir 1013 77 mg 23.1 > 20% CI 166

NE IL Neoga IL Lake Mattoon Reservoir 34849 Unknown 33.5 > 20% CI 606

KA IL New Athens IL Kaskaskia River River 3274132 NA 25.4 > 20% CI 258

NB IL New Berlin IL Spring Creek River 16852 38 mg 35.2 > 20% CI  112

158

OA IL Oakland IL Lake Oakland Reservoir 6909 26 acres 28 mg 39.7 > 20% CI 245

OL IL Olney IL East Fork Lake Reservoir 6644 5500 mg 28.8 > 20% CI 217

PA IL Palmyra IL Palmyra Modesto Lake Reservoir 826 35 acres 25 > 20% CI 147

PA IL Pana IL Lake Pana Reservoir 4545 890 mg 32.3 > 20% CI 168

PA IL Paris IL Twin Lakes Reservoir 11733 900 mg 38.7 > 20% CI 239 PIIL Pittsfield IL Lake Pittsfield Reservoir 6971 Unknown 22.6 > 20% CI 249

RO IL Rock Island IL Mississippi River River 56626192 Unknown 15.9 Continental Rivers 228

SA IL Salem IL Salem Reservoir Reservoir 2452 75 acres 12.2 11 20% CI 219

SH IL Shipman IL Shipman Reservoir Reservoir 427 13 acres ( x 9 ft) 25 > 20% CI 221

AL IL Shipman IL Mississippi River River 11525808 4 NA 24.2 Continental Rivers 143

SO IL Sorento IL Sorento Lake Reservoir 376 Unknown 15.8 11 20% CI 244

SP IL Sparta IL South City Lake Reservoir 480 33 acres 15.2 > 20% CI 259

SP IL Springfield IL Lake Springfield Lake 162178 17 000 mg 34.9 > 20% CI 169

WS IL West Salem IL West Salem Reservior & shale pit Reservoir 614 22 acres/ 2 acres 26.1 > 20% CI 183

WH IL White Hall IL White Hall Reservoir Reservoir 613 200 mg 51 acres 29.1 > 20% CI 355

SC IN Austin IN Muscatatuck River River 223967 NA 11.8 11 20% CI 307

BA IN Batesville IN Biscoff Reservoir Reservoir 2916 700 mg 200 acres 19.5 11 20% CI 310

BO IN Borden IN Packwood Branch Reservoir Reservoir 1275 445 acreft 10.8 5 10% CI 344

DU IN Dubois IN Patoka Lake Reservoir 108655 8800 acres 8.4 5 10% CI 314 Evansville IN Ohio River River 68358056 NA 5.6 Continental  113

EV IN Rivers 315

FE IN Ferdinand IN Old Lake ( No. 1) Reservoir 105 15 mg 26.2 > 20% CI 362

FW IN Fort Wayne IN St. Joseph River River 657980 Unknown 18.6 11 20% CI 320

HO IN Holland IN New Holland Lake Reservoir 348 20 acres x 12 feet 26.2 > 20% CI 328

KO IN Kokomo IN Wildcat Creek River 121637 NA 38 > 20% CI 330

LO IN Logansport IN Eel River River 524144 NA 28.3 > 20% CI 332

MC IN Michigan City IN Lake Michigan Lake 28845270 NA 8.9 Great Lakes 334 MIIN Mitchell IN East Fork of the White River River 2470938 NA 26.9 > 20% CI 335

MV IN Mount Vernon IN Ohio River River 68778138 NA 5.7 Continental Rivers 340

NV IN North Vernon IN Vernon Fork of Muscatatuck River River 68241 NA 21 > 20% CI 341

OC IN Oakland City IN Old Lake Lake 83 Unknown 33.8 > 20% CI 343

PA IN Paoli IN Lick Creek River 13424 NA 8.8 5 10% CI 345 RIIN Richmond IN Middle Fork Reservoir Lake 30825 1.01 bg 27.2 > 20% CI 346

SA IN Salem IN Lake John Hay Reservoir 5797 211 acres 11.9 11 20% CI 348

SC IN Santa Claus IN Christmas Lake Reservoir 1583 210 acreft 21.8 > 20% CI 350

SC IN Scottsburg IN Scottsburg Reservoir Reservoir 1977 100 acres 11.3 11 20% CI 351

SE IN Seymour IN East Fork of the White River River 1516709 NA 33.8 > 20% CI 352

SP IN Speedway IN Big Eagle Creek River 119080 24 000 acre ft 26.8 > 20% CI 354

SM IN St. Meinrad IN Lake Benet Reservoir 135 Unknown 4.5 5 10% CI 321

WA IN Warsaw IN Center Lake Reservoir 444 120 acres 30.3 > 20% CI 359 Westport IN Sand Creek River 60170 Unknown 43.1 > 20% CI  114

WE IN 25 ATKS Atchison KS Missouri River River 26684770 7 NA 5.1 Continental Rivers 58 GAKS Garnett KS Crystal Lake Reservoir 386 80 acre ft 6.1 5 10% CI 73 HOKS Horton KS Delaware River River 91634 Unknown 11.5 11 20% CI 71 KCKS Kansas City KS Missouri River River 26874908 2 NA 5.1 Continental Rivers 77 LEKS Leavenworth KS Missouri River River 26706117 6 11 mg 5.1 Continental Rivers 89 MIKS Milford KS Milford Lake Reservoir 15963347 16 000 acres 9.6 5 10% CI 114 RIKS Richmond KS Richmond City Lake Reservoir 557 11 acres X 35 ft max 5.1 5 10% CI 125

TO KS Topeka KS Kansas River River 36446269 NA 8.8 5 10% CI 129

VF KS Valley Falls KS Delaware River River 570021 Unknown 7.5 5 10% CI 23 WEKS Westphalia KS Lake ( No Name) Reservoir 1652 Unknown 4.8 5 10% CI 696

BA MD Bel Air MD Winter's Run River 23264 NA 8.2 5 10% CI 676

EL MD Elkton MD Big Elk Creek River 39985 Unknown 9.7 5 10% CI 683

FR MD Frederick MD Monocacy River River 456687 NA 12 5 10% CI 684

FR MD Frederick MD Monocacy River River 456040 NA 8.9 5 10% CI 699

HG MD Havre de Grace MD Susquehanna River River 17629428 NA 5.5 5 10% CI 702

LA MD Silver Spring MD Howard Duckett Reservoir ( Rocky Gorge Re Reservoir 85109 6500 mg 5.6 5 10% CI 279

BB MN Beaver Bay MN Lake Superior Lake 10719768 Unknown 0 Great Lakes 277 MIMN Minneapolis MN Mississippi River River 12527540 Unknown 7.5 Continental Rivers 275 MOMoorhead MN Red River River 4309787 Unknown 10.8 5 10% CI  115

MN 296

SC MN St. Cloud MN Mississippi River River 8774874 Unknown 4 Continental Rivers 1039

AR MO Armstrong MO Armstrong City Lake Reservoir 342 5 7 acres 10.4 5 10% CI 1003

BE MO Bethany MO Old City Lake Reservoir 191 17 acres 10.2 5 10% CI 1005

BU MO Butler MO Butler City Lake Reservoir 1965 60 acres 200 mg 6.6 5 10% CI 1006

CA MO Cameron MO Reservoirs # 1 # 2 and # 3 Reservoir 3274 # 3 : 115 acres 8.2 5 10% CI 1009

CO MO Concordia MO Edwin A. Pape Lake Reservoir 5507 1120 mg 20.6 > 20% CI 1046

ED MO Edina MO New Lake Reservoir 781 60.6 acres 8.6 5 10% CI 1071

EWMO Ewing MO Lewis County Water District Lake Reservoir 684 140 mg 14 11 20% CI 1035

FR MO Freeman MO South Grand River River 63850 130.68 mg / 20 acres 5.6 5 10% CI 1038

GA MO Gallatin MO Lake Viking Reservoir 9049 640 acres 7.1 5 10% CI 1013

GC MO Garden City MO Lake 1 Reservoir 455 65 mg 5.8 5 10% CI 1098

GE MO Gentry MO Middle Fork Water Co. Lake Reservoir 4233 160 acres 9.5 5 10% CI 1016

HI MO Higginsville MO Higginsville City Lake Reservoir 3547 550 mg 20.6 > 20% CI 1076

JC MO Jefferson City MO Missouri River River 31908199 7 N/ A 5.7 Continental Rivers 1053

LA MO Labelle MO LaBelle City Lake # 1 Reservoir 140 Unknown 14 5 10% CI 1054

LA MO Lancaster MO North Lake Reservoir 728 30 acres 6.1 5 10% CI 1058

LO MO Louisiana MO Mississippi River River 90230044 NA 22.1 Continental Rivers 1060