vvEPA United States Environmental Protection Agency Occurrence Analysis for Potential Source Waters for the Second Six-Year Review of National Primary Drinking Water Regulations ------- Office of Water (4607M) EPA815-B-09-004 October 2009 www.epa.gov/safewater ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters EPA 815-B-09-004 for the Second Six-Year Review of NPDWRs Table of Contents Executive Summary ES-1 1. Introduction 1-1 2. Cost Savings 2-1 2.1 Magnitude of Possible MCL Increase 2-1 2.2 Relative Source Water Concentration 2-2 2.3 Co-Occurring Contaminants 2-2 2.4 Treatment Technology 2-3 2.4.1 Ion Exchange (Barium) 2-3 2.4.2 Granular Activated Carbon (Alachlor, Diquat, 1,1-Dichloroethylene, Lindane, Picloram, 1,1,1-Trichloroethane) 2-4 2.4.3 Packed Tower Aeration (1,1-Dichloroethylene, 1,1,1-Trichloroethane) 2-4 2.4.4 Oxidation (Glyphosate) 2-4 2.4.5 Lime Softening (Barium) 2-4 2.4.6 Reverse Osmosis and Electrodialysis (Barium) 2-5 3. Contaminant Characteristics and Sources 3-1 4. Contaminant Occurrence Data Sources 4-1 4.1 NAWQA 4-1 4.2 STORET 4-4 4.3 PDF 4-4 4.4 Contaminant Occurrence 4-4 4.4.1 Alachlor 4-5 4.4.2 Barium 4-7 4.4.3 1,1-Dichloroethylene 4-8 4.4.4 Diquat 4-9 4.4.5 Glyphosate 4-11 4.4.6 Lindane 4-12 4.4.7 Picloram 4-14 4.4.8 1,1,1-Trichloroethane 4-16 5. Conclusions 5-1 6. References 6-1 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters EPA 815-B-09-004 for the Second Six-Year Review of NPDWRs Table of Exhibits Exhibit ES-1. Current MCLG/MCL Values and Possible MCLG Values ES-2 Exhibit 1-1. Current MCLG/MCL Values and Possible MCLG Values 1-2 Exhibit 2-1. Magnitude of Possible Change 2-1 Exhibit 2-2. Summary of Treatment Technologies 2-3 Exhibit 3-1. Potential Sources of the Contaminants 3-1 Exhibit 3-2. TRI On-site and Off-site Reported Disposal of or Otherwise Release of (in pounds) Alachlor for facilities in All Industries by State (2006) 3-2 Exhibit 3-3. TRI State Total Reported Disposal of or Otherwise Released Pounds of Alachlor for facilities in All Industries (2006) 3-3 Exhibit 3-4. TRI On-site and Off-site Reported Disposal of or Otherwise Release of (in pounds) Barium for facilities in All Industries by State (2006) 3-4 Exhibit 3-5. TRI State Total Reported Disposal of or Otherwise Released Pounds of Barium for facilities in All Industries (2006) 3-5 Exhibit 3-6. TRI On-site and Off-site Reported Disposal of or Otherwise Release of (in pounds) Barium Compounds for facilities in All Industries by State (2006) 3-6 Exhibit 3-7. TRI State Total Reported Disposal of or Otherwise Released Pounds of Barium Compounds for facilities in All Industries (2006) 3-8 Exhibit 3-8. TRI On-site and Off-site Reported Disposal of or Otherwise Release of (in pounds) Lindane for facilities in All Industries by State (2006) 3-9 Exhibit 3-9. TRI State Total Reported Disposal of or Otherwise Released Pounds of Lindane Compounds for facilities in All Industries (2006) 3-10 Exhibit 3-10. TRI On-site and Off-site Reported Disposal of or Otherwise Release of (in pounds) Picloram for facilities in All Industries by State (2006) 3-11 Exhibit 3-11. TRI State Total Reported Disposal of or Otherwise Released Pounds of Picloram Compounds for facilities in All Industries (2006) 3-12 Exhibit 3-12. TRI On-site and Off-site Reported Disposal of or Otherwise Release of (in pounds) 1,1,1-Trichloroethane for facilities in All Industries by State (2006) 3-13 Exhibit 3-13. TRI State Total Reported Disposal of or Otherwise Released Pounds of 1,1,1- Trichloroethane Compounds for facilities in All Industries (2006) 3-14 Exhibit 4-l.NAWQA Study Units 4-2 Exhibit 4-2. CWS Dataset Summary by System Size 4-3 Exhibit 4-3. CWS Summary by Water Source 4-3 Exhibit 4-4. Distance from NAWQA Sampling Stations to Nearest CWS Facility 4-3 Exhibit 4-5. Summary of Alachlor Occurrence Based on Maximum Sample Values for Locations in NAWQA 4-5 Exhibit 4-6. Summary of Alachlor Occurrence Based on Maximum Sample Values for Locations inSTORET 4-5 Exhibit 4-7. NAWQA Occurrence Data for Alachlor Based on Maximum Sample Values 4-6 Exhibit 4-8. Summary of Alachlor Occurrence for Raw Water Samples in USDA Agricultural Marketing Service Pesticide Data Program 4-6 Exhibit 4-9. Summary of Alachlor Occurrence for Finished Water Samples in USDA Agricultural Marketing Service Pesticide Data Program 4-6 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters EPA 815-B-09-004 for the Second Six-Year Review of NPDWRs Exhibit 4-10. Summary of Barium Occurrence Based on Maximum Sample Values for Locations inNAWQA 4-7 Exhibit 4-11. Summary of Barium Occurrence Based on Maximum Sample Values for Locations in STORE! 4-7 Exhibit 4-12. NAWQA Occurrence Data for Barium Based on Maximum Sample Values 4-8 Exhibit 4-13. Summary of 1,1-Dichloroethylene Occurrence Based on Maximum Sample Values for Locations in NAWQA 4-8 Exhibit 4-14. Summary of 1,1-Dichloroethylene Occurrence Based on Maximum Sample Values for Locations in STORE! 4-9 Exhibit 4-15. Plot of 1-1-Dichloroethylene NAWQA Occurrence Data 4-9 Exhibit 4-16. Crop andNoncrop Diquat Application for California in 2005 4-10 Exhibit 4-17. Estimates of National Annual Pesticide Use for Crops 4-10 Exhibit 4-18. Summary of Glyphosate Occurrence Based on Maximum Sample Values for Locations in NAWQA 4-11 Exhibit 4-19. Summary of Glyphosate Occurrence Based on Maximum Sample Values for Locations in STORET 4-11 Exhibit 4-20. Plot of Glyphosate NAWQA Occurrence Data 4-12 Exhibit 4-21. Summary of Lindane Occurrence Based on Maximum Sample Values for Locations in NAWQA 4-12 Exhibit 4-22. Summary of Lindane Occurrence Based on Maximum Sample Values for Locations in STORET 4-13 Exhibit 4-23. Plot of Lindane NAWQA Occurrence Data 4-13 Exhibit 4-24. Summary of Lindane Occurrence for Raw Water Samples in USD A Agricultural Marketing Service Pesticide Data Program 4-13 Exhibit 4-25. Summary of Lindane Occurrence for Finished Water Samples in USDA Agricultural Marketing Service Pesticide Data Program 4-14 Exhibit 4-26. Summary of Picloram Occurrence Based on Maximum Sample Values for Locations in NAWQA 4-14 Exhibit 4-27. Summary of Picloram Occurrence Based on Maximum Sample Values for Locations in STORET 4-14 Exhibit 4-28. Plot of Picloram NAWQA Occurrence Data 4-15 Exhibit 4-29. Summary of Picloram Occurrence for Raw Water Samples in USDA Agricultural Marketing Service Pesticide Data Program 4-15 Exhibit 4-30. Summary of Picloram Occurrence for Finished Water Samples in USDA Agricultural Marketing Service Pesticide Data Program 4-15 Exhibit 4-31. Summary of 1,1,1-Trichloroethane Occurrence Based on Maximum Sample Values for Locations in NAWQA 4-16 Exhibit 4-32. Summary of 1,1,1-Trichloroethane Occurrence Based on Maximum Sample Values for Locations in STORET 4-16 Exhibit 4-33. Plot of 1,1,1-Trichloroethane NAWQA Occurrence Data 4-17 Exhibit 5-1. Summary of Potential Cost Savings Factors - Occurrence 5-2 Exhibit 5-2. Summary of Potential Cost Savings Factors - Treatment 5-2 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters EPA 815-B-09-004 for the Second Six-Year Review of NPDWRs Abbreviations and Acronyms ATSDR Agency for Toxic Substances & Disease Registry BAT Best Available Technology CF Coagulation/Filtration CWS Community Water System DBF Disinfection Byproduct EDR Electrodialysis EPA U.S. Environmental Protection Agency GAC Granular Activated Carbon GIS Geographical Information System GW ground water IX Ion Exchange LDC Legacy Data Center LS Lime Softening MCL Maximum Contaminant Level MCLG Maximum Contaminant Level Goal MSBA Multi-Stage Bubbling Aeration NAICS North American Industry Classification System NAWQA National Water Quality Assessment NCFAP National Center for Food and Agricultural Policy NCOD National Contaminant Occurrence Database ND no data reported NPDWR National Primary Drinking Water Regulation OPP U.S. Environmental Protection Agency, Office of Pesticide Programs OX Oxidation PAC Powdered Activated Carbon PDF U.S. Department of Agriculture Pesticide Data Program POTW Publicly Owned Treatment Works POU Point-of-Use PTA Packed Tower Aeration PUR California Pesticide Use Reporting Database PWS Public Water System RCRA Resource Conservation and Recovery Act RO Reverse Osmosis SDWA Safe Drinking Water Act SDWIS/FED Federal Safe Drinking Water Information System SW surface water TRI Toxics Release Inventory UI Underground injection USD A U.S. Department of Agriculture USGS U.S. Geological Survey IV ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters EPA 815-B-09-004 for the Second Six-Year Review of NPDWRs Executive Summary The U.S. Environmental Protection Agency (EPA) has completed its second Six-Year Review (Six-Year Review 2) of national primary drinking water regulations (NPDWRs). The 1996 Safe Drinking Water Act (SDWA) Amendments require the U.S. Environmental Protection Agency (EPA or the Agency) to periodically review existing NPDWRs. Section 1412(b)(9) of SDWA reads: ...[t]he Administrator shall, not less than every 6 years, review and revise, as appropriate, each primary drinking water regulation promulgated under this title. Any revision of a national primary drinking water regulation shall be promulgated in accordance with this section, except that each revision shall maintain, or provide for greater, protection of the health of persons. The primary goal of the Six-Year Review process is to identify NPDWRs for possible regulatory revision. Although the statute does not define when a revision is "appropriate," as a general benchmark, EPA considered a possible revision to be "appropriate" if, at a minimum, it presents a meaningful opportunity to: improve the level of public health protection, and/or achieve cost savings while maintaining or improving the level of public health protection. For Six-Year Review 2, EPA obtained and evaluated new information that could affect a NPDWR, including information on health effects (USEPA, 2009e), analytical feasibility (USEPA, 2009b), treatment feasibility (USEPA, 2009f), and finished water occurrence (USEPA, 2009a). EPA identified new health effects assessments that indicate the possibility to raise maximum contaminant level goal (MCLG) values for a number of regulated contaminants. Consequently, EPA reviewed data on contaminant occurrence in source water to determine if there is a meaningful opportunity to achieve cost savings while maintaining or improving the level of public health protection. This document describes this review. Exhibit ES-1 shows the current MCLG values for contaminants for which new health effects assessments indicate a possible MCLG that is higher than the MCLG in the NPDWR. The new health effects information results in a wide range of possible MCLG increases. The lowest relative increase is 2 times the current MCLG for both diquat and picloram. The highest relative increase is 150 times the current MCLG for the upper bound possible MCLG for lindane. The exhibit also shows the current maximum contaminant level (MCL) values, most of which equal the MCLG values. The possible MCLG value for each contaminant is higher than the corresponding current MCL value. Thus, a revision to the MCLG for a contaminant would affect its MCL, which could reduce costs for drinking water systems that control the contaminant to meet the MCL. ES-1 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters for the Second Six-Year Review of NPDWRs EPA815-B-09-004 Exhibit ES-1. Current MCLG/MCL Values and Possible MCLG Values Contaminant Alachlor1 Barium1 1,1-Dichloroethylene2 Diquat1 Glyphosate1 Lindane (gamma-Hexachlorocyclohexane) 2 Picloram2 1,1,1-Trichloroethane1 Current MCLG/MCL (mq/L) zero (MCLG) 0.002 (MCL) 2 0.007 0.02 0.7 0.0002 0.5 0.2 Possible MCLG (mq/L) 0.04 6 0.35 0.04 14 0.001 -0.03 (depending on risk factors used for uncertainty) 1 14 1 . New health effects information during Round 2 indicates a possibility to increase MCLG. 2. New health effects information during Round 1 indicated a possibility to increase MCLG. EPA made a decision in Round 1 not to revise the NPDWR because the revision was a low priority. The potential for and magnitude of cost savings related to MCL changes depend on four factors: The magnitude of increase in the MCL The concentration of the contaminant in the source water, relative to the current MCL and the possible MCLG The presence of co-occurring contaminants treated with the same technology and their relative importance to the design and operation of the treatment technology The specific treatment technology currently employed. EPA's analysis of the potential for cost savings was constrained to readily available data. The data available to characterize contaminant occurrence was especially limited because there is no comprehensive dataset that characterizes source water quality for drinking water systems. Data from the National Water Quality Assessment (NAWQA) program conducted by the U.S. Geological Survey (USGS); EPA's STORET (short for STOrage and RETrieval) data system, which are part of EPA's Office of Ground Water and Drinking Water's National Contaminant Occurrence Database (NCOD); and U.S. Department of Agriculture (USDA) Pesticide Data Program (PDF) water monitoring survey provide useful insights into potential contaminant occurrence in source water. However, these data are not based on random or representative sampling events and, therefore, cannot be used directly to derive quantitative estimates of national occurrence in drinking water sources. Nevertheless, the available data indicate relatively infrequent contaminant occurrence in potential source waters at the levels of interest. The NAWQA data, which provide the most extensive coverage of potential source waters, indicate that only alachlor is found in concentrations that exceed the possible MCLG. In particular, two contaminants - glyphosate and picloram - are not found at levels above either the current MCLG or the possible MCLG in any of the three datasets. Diquat, which is not included in any of these datasets, has the potential to occur infrequently in source water given its less frequent use compared to the other pesticides in the table (alachlor, glyphosate, lindane, and picloram) and its tendency to dissipate quickly from surface water and be immobile in soils. ES-2 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters EPA 815-B-09-004 for the Second Six-Year Review of NPDWRs Without national estimates of contaminant occurrence in drinking water sources, EPA cannot determine how many systems currently treat for the contaminants listed in Exhibit ES-1. EPA also does not have national data regarding the treatment technologies being utilized to control these contaminants. Some technologies have higher potential for operational cost savings; however, co-occurrence considerations for all of the Best Available Technologies could diminish the potentially affected system's ability to alter treatment for possible higher MCLGs. Despite the possibility for changes in MCLG values that range from 2 to 150 times higher than current MCLs, the available occurrence data for potential drinking water sources indicate relatively low contaminant occurrence in the concentration ranges of interest. As a consequence, EPA cannot conclude that there is a meaningful opportunity for system cost savings. ES-3 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters EPA 815-B-09-004 for the Second Six-Year Review of NPDWRs 1. Introduction The U.S. Environmental Protection Agency (EPA or the Agency) has completed its second Six- Year Review (Six-Year Review 2) of national primary drinking water regulations (NPDWRs). The 1996 Safe Drinking Water Act (SDWA) Amendments require the Agency to periodically review existing NPDWRs. Section 1412(b)(9) of SDWA reads: ...[t]he Administrator shall, not less than every 6 years, review and revise, as appropriate, each primary drinking water regulation promulgated under this title. Any revision of a national primary drinking water regulation shall be promulgated in accordance with this section, except that each revision shall maintain, or provide for greater, protection of the health of persons. The primary goal of the Six-Year Review process is to identify NPDWRs for possible regulatory revision. Although the statute does not define when a revision is "appropriate," as a general benchmark, EPA considered a possible revision to be "appropriate" if, at a minimum, it presents a meaningful opportunity to: improve the level of public health protection, and/or achieve cost savings while maintaining or improving the level of public health protection. For Six-Year Review 2, EPA implemented the protocol that it developed for the first Six-Year Review (USEPA, 2003), including minor revisions developed during the current review process (USEPA, 2009d). EPA obtained and evaluated new information that could affect a NPDWR, including information on health effects (USEPA, 2009e), analytical feasibility (USEPA, 2009b), treatment feasibility (USEPA, 2009f), and finished water occurrence (USEPA, 2009a). EPA identified new health effects assessments that indicate the possibility to raise maximum contaminant level goal (MCLG) values for a number of regulated contaminants. Consequently, EPA reviewed data on contaminant occurrence in source water to determine if there is a meaningful opportunity to achieve cost savings while maintaining or improving the level of public health protection. This document describes this review. Exhibit 1-1 shows the current MCLG values for contaminants for which new health effects assessments indicate a possible MCLG that is higher than the MCLG in the NPDWR. The new health effects information results in a wide range of possible MCLG increases. The lowest relative increase is 2 times the current MCLG for both diquat and picloram. The highest relative increase is 150 times the current MCLG for the upper bound possible MCLG for lindane. Exhibit 1-1 also shows the current maximum contaminant level (MCL) values, most of which equal current MCLG values (the MCL for alachlor is higher because it is limited by analytical feasibility). The possible MCLG value for each contaminant is higher than the corresponding current MCL value. Thus, a revision to the MCLG for the contaminant would affect its MCL, which could reduce costs for drinking water systems that control the contaminant to meet the MCL. 1-1 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters for the Second Six-Year Review of NPDWRs EPA815-B-09-004 Exhibit 1-1. Current MCLG/MCL Values and Possible MCLG Values Contaminant Alachlor1 Barium1 1,1-Dichloroethylene2 Diquat1 Glyphosate1 Lindane (gamma-Hexachlorocyclohexane) 2 Picloram2 1,1,1-Trichloroethane1 Current MCLG/MCL (mq/L) zero (MCLG) 0.002 (MCL) 2 0.007 0.02 0.7 0.0002 0.5 0.2 Possible MCLG (mq/L) 0.04 6 0.35 0.04 14 0.001 -0.03 (depending on risk factors used for uncertainty) 1 14 1 . New health effects information during Round 2 indicates a possibility to increase MCLG. 2. New health effects information during Round 1 indicated a possibility to increase MCLG. EPA made a decision in Round 1 not to revise the NPDWR because the revision was a low priority. In making its recommendation to revise or take no action regarding an MCLG, EPA needs to determine whether there is a meaningful opportunity for cost savings while maintaining the same level of protection. This report provides the information EPA reviewed for this evaluation and the basis for the Agency's decisions. This report provides the information EPA reviewed for this evaluation and the basis for the Agency's decisions. During the First Six-Year Review, EPA made a recommendation not to revise several NPDWRs for which an increase in MCLG was possible, including several under consideration during the current review: 1,1-dichloroethylene, lindane, and picloram. EPA's recommendation was based on its determination that there was a low potential for cost savings. This meant that a revision was a low priority activity for the Agency because of competing workload priorities, administrative costs associated with rulemaking, and the burden on States and the regulated community to implement any regulatory change that resulted. This technical support document addresses the potential for cost savings, which depends on the potential cost savings impact at the system level and the number of systems affected. Section 2 provides a discussion of the factors affecting the potential for cost savings for each contaminant of interest. Section 3 discusses the sources of these contaminants and current usage of some of the contaminants. Section 4 summarizes water quality data that is readily available to characterize contaminant occurrence. Section 5 concludes the paper with a summary of information regarding whether possible changes to the MCLGs constitute a meaningful opportunity to reduce costs while maintaining health protection. USEPA (2009a) provides occurrence analysis information for other contaminants included in the Six-Year Review 2. 1-2 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters for the Second Six-Year Review of NPDWRs EPA815-B-09-004 2. Cost Savings The potential for and magnitude of cost savings related to MCL changes depend on four factors: The magnitude of increase in the MCL The concentration of the contaminant in the source water, relative to the current MCL and the possible MCLG The presence of co-occurring contaminants treated with the same technology and their relative importance to the design and operation of the treatment technology The specific treatment technology currently employed. The potential cost savings is generally limited by the most constrained factor for a specific treatment facility. The following sections address each of these factors. 2.1 Magnitude of Possible MCL Increase In general, the potential for cost savings is positively correlated with the magnitude of the MCL increase. A larger MCL increase can mean a greater number of systems affected and more significant changes in treatment operations. This factor can be limited, however, in the case of co-treatment. If co-occurring contaminants are present, even a large increase in the MCL for one contaminant may not permit a dramatic change in treatment operations, because the treatment system must continue operations sufficient to meet the MCLs for the other contaminants. Exhibit 2-1 presents the magnitude of possible change for the contaminants of interest. Exhibit 2-1. Magnitude of Possible Change Contaminant Alachlor Barium 1,1-Dichloroethylene Diquat Glyphosate Lindane (gamma-Hexachlorocyclohexane) Picloram 1,1,1-Trichloroethane Magnitude of Possible MCLG/MCL Increase 20 times higher (based on MCL) 3 times higher 50 times higher 2 times higher 20 times higher 5 to 150 times higher (depending on risk factors for uncertainty) 2 times higher 70 times higher One potential operational change that is highly dependent on the magnitude of the MCL increase is the degree of blending used by a treatment system. Some systems treat only a portion of the source water to a level well below the MCL and then blend the treated water with untreated water, resulting in blended water with contaminant concentrations below the MCL. An MCL increase could result in a system reducing the quantity of water being treated and increasing the quantity of untreated water in its blending operation. This change could result in reduced operating costs such as labor costs for operating the treatment system and, potentially, reduced energy costs for pumping water through the treatment process. 2-1 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters EPA 815-B-09-004 for the Second Six-Year Review of NPDWRs 2.2 Relative Source Water Concentration If an MCL increases, there are two potential scenarios for a treatment system that could result in cost savings: The source water concentration is greater than the current MCL, but less than the possible higher MCL The source water concentration is greater than both the current and possible higher MCLs. The potential cost savings under the first scenario are greater than under the second, because a system could cease treatment for the contaminant altogether. The potential for ceasing treatment, however, may be limited by the presence of co-occurring contaminants. A system may need to continue treatment for the other contaminants. The number of systems that face each scenario depends, in part, on the magnitude of the MCL increase as well as the distribution of the contaminant in source waters. Under the SDWA, public water systems (PWSs) are required to conduct compliance monitoring, and EPA is collecting monitoring data from a sample of systems. These data, however, reflect post-treatment water quality. Comprehensive data for source water quality (i.e., prior to treatment) is not readily available. EPA has identified three sources of data that characterize contaminant occurrence in potential source waters: the National Water Quality Assessment (NAWQA) program conducted by the U.S. Geological Survey (USGS), and EPA's STORET (short for STOrage and RETrieval) data system, which are part of EPA's Office of Ground Water and Drinking Water's National Contaminant Occurrence Database (NCOD), and the U.S. Department of Agriculture (USDA) Pesticide Data Program (PDF) water monitoring survey. Section 4 addresses data from these sources. 2.3 Co-Occurring Contaminants As discussed above, the presence of co-occurring contaminants is an important limiting factor affecting the cost savings that can be achieved for an MCL increase. Co-occurring contaminants, however, are significant only when the same treatment process that is used to remove the target contaminant also removes the co-occurring contaminant(s). For example, a system with coagulation/filtration to remove turbidity, followed by granular activated carbon (GAC) to remove lindane, could realize a cost savings as a result of an increase in the lindane MCL if the GAC system can be adjusted without a significant effect on turbidity removal. If, however, the GAC process also removed other regulated organic contaminants, the system may not be able to adjust its GAC operation despite a change in the lindane MCL. When the same treatment process removes multiple contaminants, potential cost savings depend on the relative importance of each contaminant to the design and operation of the process. If the contaminant with the MCL increase controls operation, and removal of other contaminants is less sensitive to operational changes, there may be a greater opportunity for cost savings, at least to the point where changes begin to affect co-occurring contaminant removal. On the other hand, if a co-occurring contaminant controls operations, and the contaminant with the MCL increase is removed as an additional benefit, a system may not be able to adjust operations. 2-2 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters for the Second Six-Year Review of NPDWRs EPA815-B-09-004 2.4 Treatment Technology Exhibit 2-2 summarizes the Best Available Technologies (BATs) for each of the seven contaminants. Exhibit 2-2. Summary of Treatment Technologies Contaminant Alachlor Barium Diquat Glyphosate 1,1-Dichloroethylene Lindane (gamma- Hexachlorocyclohexane) Picloram 1,1,1-Trichloroethane Best Available Treatment Technologies GAC IX, LS, RO, EDR GAC OX PTA, GAC GAC GAC PTA, GAC Small System Compliance Technologies GAC, POU GAC, PAC CF, IX, LS, RO, EDR, POU IX, POU RO GAC, POU GAC, PAC OX PTA, GAC, MSBA, Aeration (diffused, tray, shallow tray) GAC, POU GAC, PAC GAC, POU GAC, PAC PTA, GAC, MSBA, Aeration (diffused, tray, shallow tray, spray) GAC = Granular Activated Carbon; IX = Ion Exchange; LS = Lime Softening; POU = point-of-use; RO = Reverse Osmosis; EDR = Electrodialysis; OX = Oxidation (Chlorine or Ozone); CF = Coagulation/Filtration; PTA = Packed Tower Aeration. Sources: 40 CFR 141.61 and 141.62, USEPA 1998. The potential for cost savings (e.g., chemical use, energy, media replacement) vary by treatment technology (i.e., some technologies, once in place, are more amenable to operational changes than others). The following sections provide discussions of the factors affecting the potential cost savings for each technology in Exhibit 2-2. 2.4.1 Ion Exchange (Barium) Increasing the MCL for a target contaminant in an ion exchange system could allow for greater run times before regeneration or replacement of the ion exchange resin. This longer run length would mean a reduction in regeneration chemical use, with associated cost savings, or a reduction in the cost of replacement resin/media. Alternatively, by changing bed depth, a system can reduce the quantity of resin or media present, with similar cost savings. Therefore, these cost savings could be large relative to the total operating cost of the technology, particularly if the magnitude of the MCL change is large. Also, ion exchange systems are more likely than other systems to be operated for the removal of a single contaminant. This is particularly true of systems with contaminant-specific resins. Thus, co-occurring contaminants may be less of a concern for some systems using this technology. Even when operated to remove multiple contaminants, this technology is amenable to changes in the resin used. If one contaminant's MCL increases such that it is no longer a concern, the system can switch to a contaminant-specific resin (e.g., resin designed for arsenic removal) that is more efficient for removal of co-occurring contaminants, with potential cost savings. 2-3 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters EPA 815-B-09-004 for the Second Six-Year Review of NPDWRs 2.4.2 Granular Activated Carbon (Alachlor, Diquat, 1,1-Dichloroethylene, Lindane, Picloram, 1,1,1-Trichloroethane) Similar to ion exchange, granular activated carbon (GAC) systems treating for a contaminant with an increased MCL may be able to extend their run length before regeneration or replacement of the GAC media or decrease the bed depth to reduce the GAC quantity. Cost savings could be large relative to the total operating cost of the technology, particularly if the magnitude of the MCL change is large. Unlike ion exchange, however, GAC removes a wide spectrum of organic and inorganic compounds including disinfection byproduct (DBF) precursors, and is more likely to be used for the removal of multiple contaminants. Thus, co-occurring contaminants may limit or eliminate the potential for cost savings, depending on which contaminant(s) have the greatest influence on GAC operation. Also, although all GAC media are not the same, there is less potential for a change in GAC media to result in significant cost savings. 2.4.3 Packed Tower Aeration (1,1 -Dichloroethylene, 1,1,1- Trichloroethane) An increased MCL could allow packed tower aeration (PTA) systems treating for 1,1- dichloroethylene or 1,1,1-trichloroethane to reduce the air-to-water ratio, resulting in reduced energy cost for blowers. Blower energy costs, however, make up a small portion of total operating costs. Thus, the cost savings could be small relative to the total operating cost of the technology. Also like GAC, PTA can remove a wide range of contaminants, specifically volatile contaminants, and is more likely to be used for the removal of multiple contaminants. Thus, co- occurring contaminants may eliminate the potential for cost savings or limit the savings to the extent 1,1-dichloroethylene or 1,1,1-trichloroethane treatment controls the PTA system's air-to- water ratio. 2.4.4 Oxidation (Glyphosate) With an increased MCL, systems using oxidation to treat for glyphosate could reduce the dose of chlorine or ozone, resulting in reduced chemical cost. Chlorination and ozonation, however, typically are installed for the primary purpose of disinfecting drinking water. In other words, there would almost always be a co-occurring contaminant (i.e., bacteria, viruses, and parasites) in these systems, and glyphosate treatment would be a secondary benefit of the system. Cost savings in these systems would be limited to the extent glyphosate treatment controls the chemical dose. Although chemical costs make up a large portion of operating cost for these technologies, the ability to reduce these costs significantly would likely be small because of disinfection needs. It is unlikely that systems would be able to cease their oxidation treatment because of an increase in the glyphosate MCL, given the need for disinfection. 2.4.5 Lime Softening (Barium) An increased MCL may allow lime softening systems to reduce the dose of treatment chemicals (coagulant or lime), resulting in reduced cost. Similar to oxidation, however, lime softening systems also are typically installed for another primary purpose (e.g., solids and/or hardness removal). The treatment of the contaminant with the increasing MCL would likely be a 2-4 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters EPA 815-B-09-004 for the Second Six-Year Review of NPDWRs secondary benefit of the system. Cost savings would be limited to the extent the contaminant with the MCL increase controls the coagulant or lime dose. Although chemical costs make up a moderate portion of operating cost for this technology, the ability to reduce these costs significantly would likely be small because of treatment needs for other contaminants. It is unlikely systems would be able to cease lime softening treatment, given the need to continue removal of solids and/or hardness. 2.4.6 Reverse Osmosis and Electrodialysis (Barium) These two technologies generally achieve a very high removal rate for a wide variety of contaminants. Although some operational adjustments may be possible (e.g., changes in blending ratios), these changes would not have a dramatic effect on operating costs unless there are no co- occurring contaminants. These technologies are very likely to be used for removal of multiple contaminants, thereby limiting the potential for cost savings due to an MCL change for one contaminant. 2-5 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters for the Second Six-Year Review of NPDWRs EPA815-B-09-004 3. Contaminant Characteristics and Sources Toxic pollutants can be introduced to surface water through natural sources as well as human activities. Exhibit 3-1 provides a brief summary of the uses and potential sources for the pollutants of interest. Exhibit 3-1. Potential Sources of the Contaminants Contaminant Sources of Potential Release to the Environment Description/Uses Environmental Fate and Transport Alachlor Agricultural runoff Herbicide used for weed control: corn, soybeans, sorghum, peanuts, and beans. Low absorption to soil; soluble and highly mobile in water; leaches to groundwater. Barium Industrial waste; drilling waste ground application, offshore drilling waste water; copper smelting; erosion of natural deposits. Naturally occurring metal; used in oil and gas drilling mud, jet fuel, pesticides, paint, bricks, ceramics, glass, and rubber. Leaching and erosion of natural deposits into groundwater; atmospheric deposition; precipitate out of aquatic media as insoluble salt; adsorb to suspended solids in surface water; not mobile in soil systems. 1,1- Dichloroethylene Atmospheric emissions or wastewater discharge from manufacturing plants. Industrial chemical used in making adhesives, synthetic fibers, refrigerants, food packaging, and coating resins. Hydrophobic; highly volatile; if spilled on land, may leach to groundwater. Diquat Agricultural runoff; manufacturing wastewater discharges. Herbicide used to control plant growth in aquatic environments and as agricultural and residential herbicide. Permanently adsorbs to soil; rapidly adheres to sediments when released to water; immobile. Glyphosate Direct discharge during application; manufacturing wastewater discharges. Herbicide used on food and non-food field crops as well as a plant growth regulator. Strongly adsorbs to soil, immobile; unlikely to leach to groundwater; likely to adhere to sediments when released to surface water by aquatic use and erosion. Lindane (gamma- Hexachlorocycloh exane) Agricultural runoff; atmospheric emissions; rain and snow deposition. Insecticide used to treat a variety of crop seeds; all agricultural application of this chemical will cease by October 2009. Volatile; sorbs to soil, leaching to groundwater (soluble in water at 7 mg/L). Picloram Runoff from agricultural, forest, and rights-of-way application. Herbicide used to control feed crop pastures, nonfood crops (rights-of- way), and in forestry. Highly soluble and mobile in water; leaches to groundwater, no degradation. 1,1,1- Trichloroethane Atmospheric emissions or wastewater discharge from manufacturing plants, discharge or leaching from landfills. Industrial chemical used as a solvent and in production of hydrofluorocarbons. Highly volatile; sorbs to soil, leaching to groundwater; atmospheric deposition; moderate solubility. Sources: USEPA OPP 2006; ATSDR 2005; ATSDR 2007; ATSDR 2002; USEPA 2002; USEPA 1995a; USEPA 1993; USEPA 2006c; USEPA 1995b; USEPA 2007; ATSDR 2006. 3-1 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters for the Second Six-Year Review of NPDWRs EPA815-B-09-004 EPA collected the most recently reported state level releases and disposal data for the pollutants of concern from EPA's Toxic Release Inventory (TRI). This data identifies states that are most likely to have anthropogenic sources of the contaminants of interest that are reported to the TRI, which excludes agricultural applications of pesticides. No release or disposal were reported for 1,1-dichloroethane, diquat, or glyphosate. The following table and map exhibits show the total number of pounds of each pollutant of interest reportedly released or disposed of on-site to different media, the total off-site disposal/releases, and a graphical representation of the total releases/disposal. Alachlor releases occurred only in Iowa in 2006 (see Exhibit 3-2 and Exhibit 3-3). Most of the 274 pounds were released to air; 12 pounds were discharged to water. Exhibit 3-2. TRI On-site and Off-site Reported Disposal of or Otherwise Release of (in pounds) Alachlor for facilities in All Industries by State (2006) State Iowa Total Air1 (a) 262 262 Surface Water Discharges2 (b) 12 12 Under- ground Injection3 (c) 0 0 On-site Landfill Disposal4 (d) 0 0 Other On- site Releases5 (e) 0 0 Total On-site Disposal or Other Releases (0=(a)+(b)+ (cMdMe) 274 274 Total Off- site Disposal or Other Releases6 (h) 0 0 Total On- and Off-site Disposal or Other Releases 0)=(f)+(h) 274 274 Source: USEPA, 2008 ND: no data reported 1. Includes fugitive and point source air releases. Fugitive emissions are all releases to air that are not released through a confined air stream. Fugitive emissions include equipment leaks, evaporative losses from surface impoundments and spills, and releases from building ventilation systems. Point source air emissions occur through confined air streams such as stacks, vents, ducts, or pipes. 2. Releases to water include discharges to streams, rivers, lakes, oceans, and other bodies of water. This includes releases from contained sources, such as industrial process outflow pipes or open trenches. Releases due to runoff, including storm water runoff are also reportable to TRI. 3. Underground injection is the subsurface emplacement of fluids through wells including Class I, II, III, IV, or V wells. 4. Total On-Site Disposal to Class I Ul RCRA Landfills and other Landfills. 5. Includes land treatment, surface impoundments, and other land disposal. Other disposal is the disposal of the toxic chemical to land at the facility that does not fall into one of the other on-site land releases listed. Other disposal includes such activities as placement in waste piles and spills or leaks. 6. Disposal of toxic chemicals in waste to off-site locations include discharges to Publicly Owned Treatment Works (POTWs) or disposal at other off-site facilities. Other off-site disposal facilities may include underground injection, landfills, solidification/stabilization (metals), water treatment (metals), surface impoundments, land treatment, waste broker, or other unknown off-site facilities. 3-2 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters for the Second Six-Year Review of NPDWRs EPA815-B-09-004 Exhibit 3-3. TRI State Total Reported Disposal of or Otherwise Released Pounds of Alachlor for facilities in All Industries (2006) Legend Total On-Site and Off-Site Disposal or Other Releases |lbs.) National releases and disposal of barium were reported to be approximately 6.8 million pounds in 2006. Exhibit 3-4 and Exhibit 3-5 show that Arizona reported the greatest release and disposal of 2.5 million pounds (36.3%) followed by Kansas (0.65 million pounds), Oregon (0.63 million pounds), and Pennsylvania (0.55 million pounds). In Arizona all releases and disposal came from the electric utilities sector (NAICS 2211) and most was disposed of in on-site landfills. The total release directly to surface water in 2006 was 6,640 pounds. Nebraska reported the highest release to surface water of 3,913 pounds. 3-3 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters for the Second Six-Year Review of NPDWRs EPA815-B-09-004 Exhibit 3-4. TRI On-site and Off-site Reported Disposal of or Otherwise Release of (in pounds) Barium for facilities in All Industries by State (2006) State Alabama Alaska Arizona California Colorado Connecticut Delaware Georgia Idaho Illinois Indiana Iowa Kansas Kentucky Louisiana Michigan Minnesota Nebraska New Jersey New York North Carolina Ohio Oregon Pennsylvania Puerto Rico South Carolina South Dakota Tennessee Texas Utah Virginia Washington West Virginia Wisconsin Total Air1 (a) 4 4,808 4,529 1,607 28,643 3 35 98 29 56 6 715 7,533 79,829 0 2 8.8 55,056 130 0 31.4 10,230 0 1,556 0 274 1,000 0 2,511 503 0 49 0 0 199,246 Surface Water Discharges2 (b) 313 ND ND ND 0 ND 11 ND ND 0 ND 0 0 250 ND 0 ND 3,913 ND 314 501 1,089 7 0 ND ND ND ND 242 0 ND ND ND ND 6,640 Under- ground Injection3 (c) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 18,086 0 0 0 0 0 0 0 0 0 0 0 0 18,086 On-site Landfill Disposal4 (d) 0 0 2,273,949 622,433 0 0 0 0 164,671 0 0 0 131,690 0 16,000 0 0 0 0 6,072 0 82,086 631,136 335,647 0 0 47,646 0 44,385 107,604 0 0 0 0 4,463,319 Other On- site Releases5 (e) 0 0 235 18 9,547 0 0 0 0 0 0 0 0 0 0 0 0 22,524 0 0 0 0 90 0 0 0 0 0 0 0 0 0 90,000 0 122,414 Total On- site Disposal or Other Releases (0=(a)+(b)+ (c)+(d)+(e) 317 4,808 2,278,713 624,058 38,190 3 46 98.1 164,700 56 6 715 139,223 80,079 16,000 2 8.8 81,493 130 6,386 532 93,405 631,233 337,203 0 274 48,646 0 47,138 108,107 0 49 90,000 0 4,791,619 Total Off- site Disposal or Other Releases6 (h) 2,927 177,652 173,489 112 0 2,565 0 10,350 0 46,878 28,353 32,395 507,055 0 1,980 88,487 1,005 379,261 6,387 8,700 3,110 81,556 12 213,707 5 48 0 33,629 57,339 30,017 40,470 14 0 31,850 1,959,353 Total On- and Off- site Disposal or Other Releases (i)=(f>(h) 3,244 182,460 2,452,202 624,170 38,190 2,568 46 10,448 164,700 46,934 28,359 33,110 646,278 80,079 17,980 88,489 1,014 460,754 6,517 15,086 3,642 174,961 631,244 550,910 5 322 48,646 33,629 104,477 138,124 40,470 63 90,000 31,850 6,750,972 Source: USEPA, 2008 ND: no data reported 1. Includes fugitive and point source air releases. Fugitive emissions are all releases to air that are not released through a confined air stream. Fugitive emissions include equipment leaks, evaporative losses from surface impoundments and spills, and releases from building ventilation systems. Point source air emissions occur through confined air streams such as stacks, vents, ducts, or pipes. 2. Releases to water include discharges to streams, rivers, lakes, oceans, and other bodies of water. This includes releases from 3-4 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters for the Second Six-Year Review of NPDWRs EPA815-B-09-004 Exhibit 3-4. TRI On-site and Off-site Reported Disposal of or Otherwise Release of (in pounds) Barium for facilities in All Industries by State (2006) State Air1 (a) Surface Water Discharges2 (b) Under- ground Injection3 (c) On-site Landfill Disposal4 (d) Other On- site Releases5 (e) Total On- site Disposal or Other Releases (0=(a)+(b)+ (c)+(d)+(e) Total Off- site Disposal or Other Releases6 (h) Total On- and Off- site Disposal or Other Releases (i)=(f>(h) contained sources, such as industrial process outflow pipes or open trenches. Releases due to runoff, including storm water runoff are also reportabletoTRI. 3. Underground injection is the subsurface emplacement of fluids through wells including Class I, II, III, IV, or V wells. 4. Total On-Site Disposal to Class I Ul RCRA Landfills and other Landfills. 5. Includes land treatment, surface impoundments, and other land disposal. Other disposal is the disposal of the toxic chemical to land at the facility that does not fall into one of the other on-site land releases listed. Other disposal includes such activities as placement in waste piles and spills or leaks. 6. Disposal of toxic chemicals in waste to off-site locations include discharges to Publicly Owned Treatment Works (POTWs) or disposal at other off-site facilities. Other off-site disposal facilities may include underground injection, landfills, solidification/stabilization (metals), water treatment (metals), surface impoundments, land treatment, waste broker, or other unknown off-site facilities. Exhibit 3-5. TRI State Total Reported Disposal of or Otherwise Released Pounds of Barium for facilities in All Industries (2006) ALASKA 0 100 200 400 Legend Total On-SItt and Off-Site Dispoial or other Releases (IDs.) Barium ^ 5-«M6 HH «en mate IB 133-161 - M6378 Miles 3-5 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters for the Second Six-Year Review of NPDWRs EPA815-B-09-004 National releases and disposal of barium compounds were reported to be approximately 224.7 million pounds in 2006. Exhibit 3-6 and Exhibit 3-7 show that Texas reported the greatest release and disposal of 16.5 million pounds (7.4%) followed by North Dakota (13.9 million pounds) and Michigan (12.6 million pounds). In Texas, 94% of the reported releases and disposal came from the electric utilities sector (NAICS 2211) and 2% came from the chemical sector (NAICS 325). The total release directly to surface waters in 2006 was approximately one million pounds. Illinois reported the highest release to surface water of 123,897 pounds followed by Tennessee (119,997 pounds) and South Carolina (75,055 pounds). Exhibit 3-6. TRI On-site and Off-site Reported Disposal of or Otherwise Release of (in pounds) Barium Compounds for facilities in All Industries by State (2006) State Alabama Alaska Arizona Arkansas California Colorado Connecticut Delaware Florida Georgia Hawaii Idaho Illinois Indiana Iowa Kansas Kentucky Louisiana Maine Maryland Massachusetts Michigan Minnesota Mississippi Missouri Montana Nebraska Nevada New Hampshire New Jersey Air1 (a) 39,293 26,894 19,259 53,429 12,052 14,733 2,545 10,601 27,228 66,339 64 7,456 154,529 95,425 186,258 93,805 58,941 49,943 1,448 8,048 3,684 64,032 52,501 4,106 161,647 114,897 59,038 898 1,267 8,128 Surface Water Discharges2 (b) 68,042 ND ND 75,026 260 930 7 10,593 10,727 62,809 ND ND 123,897 34,454 5,515 747 67,955 30,962 4,600 896 1,061 39,122 2,860 20,656 16,584 795 5 0 ND 39 Under- ground Injection3 (c) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 541 0 3 0 0 0 51,600 0 0 0 0 0 0 On-site Landfill Disposal4 (d) 1,819,037 149,061 1,618,845 3,243,243 7,838 4,810,972 0 280,000 1,789,344 817,488 0 10,634 476,000 4,983,355 1,341,054 3,461,575 2,671,201 2,012,600 82,130 38,246 9,572 5,807,055 2,942,269 1,043,777 1,673,048 8,398,812 1,828,368 841,677 0 0 Other On- site Releases5 (e) 8,852,004 1,243 5,576,154 344,456 0 415 0 0 2,411,543 7,801,677 0 48,573 4,822,273 3,765,383 1,894,000 1,995,885 2,648,100 1,012,871 0 197,754 228,932 4,307,884 5,575,059 91,925 5,398,947 165,155 10 53,390 13,000 0 Total On- site Disposal or Other Releases (0=(a)+(b)+ (c)+(d)+(e) 10,778,376 177,198 7,214,258 3,716,153 20,150 4,827,050 2,553 301,194 4,238,842 8,748,313 64 66,663 5,576,699 8,878,617 3,426,827 5,552,012 5,446,197 3,106,376 88,178 244,947 243,249 10,218,093 8,572,689 1,160,464 7,250,226 8,679,659 1,887,421 895,965 14,267 8,167 Total Off- site Disposal or Other Releases6 (h) 53,416 1,243 19,112 37,327 14,516 3,911,998 99,338 149,119 342,315 62,617 50,896 47,000 3,562,257 819,017 1,451,238 0 1,891,428 1,338,912 18,197 954,092 103,068 2,364,276 782,215 93,627 103,723 440,377 336,671 35 3,558 289,375 Total On- and Off-site Disposal or Other Releases (i)=(f)+(h) 10,831,793 178,441 7,233,370 3,753,480 34,666 8,739,048 101,891 450,313 4,581,157 8,810,930 50,960 113,663 9,138,956 9,697,633 4,878,065 5,552,012 7,337,625 4,445,289 106,375 1,199,039 346,317 12,582,369 9,354,903 1,254,090 7,353,948 9,120,036 2,224,092 896,000 17,825 297,542 3-6 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters for the Second Six-Year Review of NPDWRs EPA815-B-09-004 Exhibit 3-6. TRI On-site and Off-site Reported Disposal of or Otherwise Release of (in pounds) Barium Compounds for facilities in All Industries by State (2006) State New Mexico New York North Carolina North Dakota Ohio Oklahoma Oregon Pennsylvania Puerto Rico Rhode Island South Carolina South Dakota Tennessee Texas Utah Vermont Virginia Washington West Virginia Wisconsin Wyoming Total Air1 (a) 13,880 23,342 24,666 41,053 70,988 23,899 15,617 42,320 2,847 5 25,317 1,120 20,231 143,884 4,498 0 5,159 1,048 6,418 51,094 41,688 1,957,560 Surface Water Discharges2 (b) 2,100 13,186 58,290 20,722 34,283 15,920 3,939 29,942 0 18 75,055 120 119,997 43,683 80 ND 37,270 3,105 15,186 8,283 4,987 1,064,708 Under- ground Injection3 (c) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 52,144 On-site Landfill Disposal4 (d) 3,683,605 607,765 299,831 1,645,308 1,671,929 1,069,250 250,000 1,229,599 0 0 674,795 588,856 1,310,070 10,620,521 3,314,131 0 1,027,000 26,143 3,141,468 285,180 6,068,618 89,671,269 Other On- site Releases5 (e) 1,210,133 25 3,545,025 5,347,505 3,663,861 396,268 0 193,816 0 0 912,137 0 4,012,858 2,444,136 180,397 0 516,161 1,010,646 1,089,119 656,674 675,635 83,061,028 Total On- site Disposal or Other Releases (0=(a)+(b)+ (c)+(d)+(e) 4,909,718 644,317 3,927,812 7,054,588 5,441,061 1,505,337 269,556 1,495,677 2,847 23 1,687,303 590,095 5,463,156 13,252,225 3,499,106 0 1,585,590 1,040,942 4,252,191 1,001,231 6,790,928 175,754,568 Total Off- site Disposal or Other Releases6 (h) 755 1,250,835 427,201 6,849,716 3,723,633 395,945 40,196 3,196,635 0 10,343 596,404 169,306 5,514,045 3,289,907 44,609 29,485 432,784 88,564 1,159,751 1,743,425 678,126 48,982,625 Total On- and Off-site Disposal or Other Releases (i)=(f)+(h) 4,910,473 1,895,152 4,355,012 13,904,304 9,164,694 1,901,282 309,752 4,692,313 2,847 10,366 2,283,707 759,401 10,977,201 16,542,131 3,543,715 29,485 2,018,374 1,129,506 5,411,941 2,744,655 7,469,054 224,737,194 Source: USEPA, 2008 ND: no data reported 1. Includes fugitive and point source air releases. Fugitive emissions are all releases to air that are not released through a confined air stream. Fugitive emissions include equipment leaks, evaporative losses from surface impoundments and spills, and releases from building ventilation systems. Point source air emissions occur through confined air streams such as stacks, vents, ducts, or pipes. 2. Releases to water include discharges to streams, rivers, lakes, oceans, and other bodies of water. This includes releases from contained sources, such as industrial process outflow pipes or open trenches. Releases due to runoff, including storm water runoff are also reportable to TRI. 3. Underground injection is the subsurface emplacement of fluids through wells including Class I, II, III, IV, or V wells. 4. Total On-Site Disposal to Class I Ul RCRA Landfills and other Landfills. 5. Includes land treatment, surface impoundments, and other land disposal. Other disposal is the disposal of the toxic chemical to land at the facility that does not fall into one of the other on-site land releases listed. Other disposal includes such activities as placement in waste piles and spills or leaks. 6. Disposal of toxic chemicals in waste to off-site locations include discharges to Publicly Owned Treatment Works (POTWs) or disposal at other off-site facilities. Other off-site disposal facilities may include underground injection, landfills, solidification/stabilization (metals), water treatment (metals), surface impoundments, land treatment, waste broker, or other unknown off-site facilities. 3-7 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters EPA 815-B-09-004 for the Second Six-Year Review of NPDWRs Exhibit 3-7. TRI State Total Reported Disposal of or Otherwise Released Pounds of Barium Compounds for facilities in All Industries (2006) 0 100 200 400 Legend Totil On-SIrt ind OIT-SIK Disposal or Other Rttoixi (Ibs.) B«num Compound* j !M7 - 12WO&0 j^B C5X09I - 3753*80 I I I I I I I I I Miles As shown in Exhibit 3-8 and Exhibit 3-9, nationally only 10 pounds of lindane were reportedly released and disposed of in 2006 from three states including Arkansas, Ohio, and Utah. Half of the 10 pounds were released into the air, while the other 5 pounds were disposed of at off-site facilities. 3-8 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters for the Second Six-Year Review of NPDWRs EPA815-B-09-004 Exhibit 3-8. TRI On-site and Off-site Reported Disposal of or Otherwise Release of (in pounds) Lindane for facilities in All Industries by State (2006) State Arkansas Ohio Utah Total Air1 (a) 1 0 4 5 Surface Water Discharges2 (b) ND 0 ND 0 Under- ground Injection3 (c) 0 0 0 0 On-site Landfill Disposal4 (d) 0 0 0 0 Other On- site Releases5 (e) 0 0 0 0 Total On-site Disposal or Other Releases (0=(a)+(b)+(c) +(d)+(e) 1 0 4 5 Total Off- site Disposal or Other Releases6 (h) 0 5 0 5 Total On- and Off-site Disposal or Other Releases (i)=(f)+(h) 1 5 4 10 Source: USEPA, 2008 ND: no data reported 1. Includes fugitive and point source air releases. Fugitive emissions are all releases to air that are not released through a confined air stream. Fugitive emissions include equipment leaks, evaporative losses from surface impoundments and spills, and releases from building ventilation systems. Point source air emissions occur through confined air streams such as stacks, vents, ducts, or pipes. 2. Releases to water include discharges to streams, rivers, lakes, oceans, and other bodies of water. This includes releases from contained sources, such as industrial process outflow pipes or open trenches. Releases due to runoff, including storm water runoff are also reportable to TRI. 3. Underground injection is the subsurface emplacement of fluids through wells including Class I, II, III, IV, or V wells. 4. Total On-Site Disposal to Class I Ul RCRA Landfills and other Landfills. 5. Includes land treatment, surface impoundments, and other land disposal. Other disposal is the disposal of the toxic chemical to land at the facility that does not fall into one of the other on-site land releases listed. Other disposal includes such activities as placement in waste piles and spills or leaks. 6. Disposal of toxic chemicals in waste to off-site locations include discharges to Publicly Owned Treatment Works (POTWs) or disposal at other off-site facilities. Other off-site disposal facilities may include underground injection, landfills, solidification/stabilization (metals), water treatment (metals), surface impoundments, land treatment, waste broker, or other unknown off-site facilities. 3-9 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters for the Second Six-Year Review of NPDWRs EPA815-B-09-004 Exhibit 3-9. TRI State Total Reported Disposal of or Otherwise Released Pounds of Lindane Compounds for facilities in All Industries (2006) Legend Total On-Site and Off-Site Disposal or Other Releases fibs.) Lindane 0 100 200 400 . Miles National releases and disposal of picloram were reported to be approximately 51.8 thousand pounds in 2006. As shown in Exhibit 3-10 and Exhibit 3-11, while three states reported releases (Michigan, Missouri, and Texas), 99% of the releases and disposal were in Texas. All of the reported releases and disposal came from the chemical sector (NAICS 325) and most was disposed of in on-site landfills. The total release directly to surface water in 2006 was only 350 pounds, all of which was reported in Michigan. 3-10 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters for the Second Six-Year Review of NPDWRs EPA815-B-09-004 Exhibit 3-10. TRI On-site and Off-site Reported Disposal of or Otherwise Release of (in pounds) Picloram for facilities in All Industries by State (2006) State Michigan Missouri Texas Total Air1 (a) 14 46 201 261 Surface Water Discharges2 (b) 350 ND 0 350 Under- ground Injection3 (c) 0 0 0 0 On-site Landfill Disposal4 (d) 0 0 51,133 51,133 Other On- site Releases5 (e) 0 0 0 0 Total On-site Disposal or Other Releases (0=(a)+(b)+(c) +(d)+(e) 364 46 51,334 51,744 Total Off- site Disposal or Other Releases6 (h) 0 8 0 8 Total On- and Off-site Disposal or Other Releases (i)=(f)+(h) 364 54 51,334 51,752 Source: USEPA, 2008 ND: no data reported 1. Includes fugitive and point source air releases. Fugitive emissions are all releases to air that are not released through a confined air stream. Fugitive emissions include equipment leaks, evaporative losses from surface impoundments and spills, and releases from building ventilation systems. Point source air emissions occur through confined air streams such as stacks, vents, ducts, or pipes. 2. Releases to water include discharges to streams, rivers, lakes, oceans, and other bodies of water. This includes releases from contained sources, such as industrial process outflow pipes or open trenches. Releases due to runoff, including storm water runoff are also reportable to TRI. 3. Underground injection is the subsurface emplacement of fluids through wells including Class I, II, III, IV, or V wells. 4. Total On-Site Disposal to Class I Ul RCRA Landfills and other Landfills. 5. Includes land treatment, surface impoundments, and other land disposal. Other disposal is the disposal of the toxic chemical to land at the facility that does not fall into one of the other on-site land releases listed. Other disposal includes such activities as placement in waste piles and spills or leaks. 6. Disposal of toxic chemicals in waste to off-site locations include discharges to Publicly Owned Treatment Works (POTWs) or disposal at other off-site facilities. Other off-site disposal facilities may include underground injection, landfills, solidification/stabilization (metals), water treatment (metals), surface impoundments, land treatment, waste broker, or other unknown off-site facilities. 3-11 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters for the Second Six-Year Review of NPDWRs EPA815-B-09-004 Exhibit 3-11. TRI State Total Reported Disposal of or Otherwise Released Pounds of Picloram Compounds for facilities in All Industries (2006) Legend Total On-Sile and Off-Site Disposal or Other Releases (Ibs.) 0 100 200 400 I I i I II t f I PUKRTO RICO National releases and disposal of 1,1,1-trichloroethane were reported to be approximately 119; thousand pounds in 2006. Exhibit 3-12 and Exhibit 3-13 show that Louisiana reported the greatest release and disposal of 57.0 thousand pounds (47.6%) followed by Minnesota (36.3 thousand pounds) and New Mexico (10.8 thousand pounds). In Louisiana all releases and disposal came from the chemical sector (NAICS 325) and most was released into the air. The total release directly to surface water in 2006 was only 53 pounds. Louisiana also reported the highest release to surface water of 47 pounds. 3-12 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters for the Second Six-Year Review of NPDWRs EPA815-B-09-004 Exhibit 3-12. TRI On-site and Off-site Reported Disposal of or Otherwise Release of (in pounds) 1,1,1-Trichloroethane for facilities in All Industries by State (2006) State Arkansas California Illinois Indiana Kentucky Louisiana Minnesota Mississippi Missouri Nebraska New Jersey New Mexico Ohio Pennsylvania Texas Utah Virginia Total Air1 (a) 102 272 1 500 1,620 57,018 36,337 1 ND 10 1 0 840 500 1,468 9,654 10 108,334 Surface Water Discharges2 (b) ND ND 0 ND 4 47 ND 0 ND 0 2 ND 0 0 0 ND ND 53 Under- ground Injection3 (c) 0 0 0 0 0 0 0 0 ND 0 0 0 0 0 0 0 0 0 On-site Landfill Disposal4 (d) 0 0 0 0 0 0 0 0 ND 11 0 0 0 0 0 0 0 11 Other On- site Releases5 (e) 0 0 0 0 0 0 0 0 ND 0 0 10,806 0 0 0 0 0 10,806 Total On-site Disposal or Other Releases (0=(a)+(b)+(c) +(d)+(e) 102 272 1 500 1,624 57,065 36,337 1 ND 21 3 10,806 840 500 1,468 9,654 10 119,204 Total Off- site Disposal or Other Releases6 (h) 0 90 21 0 0 1 0 0 0 0 200 0 255 5 0 4 0 576 Total On- and Off-site Disposal or Other Releases (i)=(f)+(h) 102 362 22 500 1,624 57,066 36,337 1 0 21 203 10,806 1,095 505 1,468 9,658 10 119,780 Source: USEPA, 2008 ND: no data reported 1. Includes fugitive and point source air releases. Fugitive emissions are all releases to air that are not released through a confined air stream. Fugitive emissions include equipment leaks, evaporative losses from surface impoundments and spills, and releases from building ventilation systems. Point source air emissions occur through confined air streams such as stacks, vents, ducts, or pipes. 2. Releases to water include discharges to streams, rivers, lakes, oceans, and other bodies of water. This includes releases from contained sources, such as industrial process outflow pipes or open trenches. Releases due to runoff, including storm water runoff are also reportable to TRI. 3. Underground injection is the subsurface emplacement of fluids through wells including Class I, II, III, IV, or V wells. 4. Total On-Site Disposal to Class I Ul RCRA Landfills and other Landfills. 5. Includes land treatment, surface impoundments, and other land disposal. Other disposal is the disposal of the toxic chemical to land at the facility that does not fall into one of the other on-site land releases listed. Other disposal includes such activities as placement in waste piles and spills or leaks. 6. Disposal of toxic chemicals in waste to off-site locations include discharges to Publicly Owned Treatment Works (POTWs) or disposal at other off-site facilities. Other off-site disposal facilities may include underground injection, landfills, solidification/stabilization (metals), water treatment (metals), surface impoundments, land treatment, waste broker, or other unknown off-site facilities. 3-13 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters for the Second Six-Year Review of NPDWRs EPA815-B-09-004 Exhibit 3-13. TRI State Total Reported Disposal of or Otherwise Released Pounds of 1,1,1-Trichloroethane Compounds for facilities in All Industries (2006) 0 100 200 I t i I II Legend Total on-site and Off-Site Disposal or Other Releases (Ibs.) 111 TnctioloeliiCTe 1 505 ill '.- ^^ 1675 . 10606 PUKRTO RICO 3-14 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters EPA 815-B-09-004 for the Second Six-Year Review of NPDWRs 4. Contaminant Occurrence Data Sources EPA has identified three sources of data that provide information on contaminant occurrence in source water: USGS' NAWQA Program, EPA's STORE! data system, and USDA's Pesticide Data Program (PDF) water monitoring survey. This section provides background information on these three sources as well as occurrence summary data for the seven contaminants of interest. 4.1 NAWQA In 1991, USGS implemented the NAWQA Program, in part, to characterize the condition of streams, rivers, and ground water in the U.S. From 1991-2001, the NAWQA Program conducted interdisciplinary assessments, including water chemistry, hydrology, land use, stream habitat, and aquatic life, and established a baseline understanding of water-quality conditions in 51 of the Nation's river basins and aquifers, referred to as Study Units (USGS, 2006a). Exhibit 4-1 depicts these study units. USGS selected these Study Units to reflect important hydrologic and ecological resources; critical sources of contaminants, including agricultural, urban, and natural sources; and a high percentage of population served by municipal water supply and irrigated agriculture. These areas account for more than 70 percent of total water use (excluding thermoelectric and hydropower) and more than 50 percent of the population's supply of drinking water (Gilliom, 2006). The Study-Unit design used a rotational sampling scheme; therefore, sampling intensity varied year to year at the different sites. During the first decade, 20 investigations began in 1991; 16 in 1994; and 15 in 1997. During the time period 2001-2012, rotational monitoring will continue in 42 of the 51 Study Units. USGS has made most of this data available through the NAWQA Warehouse. EPA collected and analyzed all available water quality sampling data for the seven contaminants of interest. EPA selected the maximum reported concentration for each contaminant analyzed at each location. The results shown below are based on these maximum concentrations and, therefore, represent upper bounds on contaminant occurrence in the NAWQA database. The NAWQA data include latitude and longitude fields for the water quality sampling stations. EPA used these data along with latitude and longitude data in the Federal Safe Drinking Water Information System (SDWIS/FED) for community water system (CWS) facilities (e.g., intake well or treatment plant) to characterize the proximity of NAWQA sampling stations to these systems. EPA used a 2007 data extract of system, facility, and location information from SDWIS/FED for the analysis. EPA developed an initial dataset that contained 108,243 facility location records for 40,875 active CWSs that did not purchase water. EPA selected the records for facilities associated with water sources: infiltration gallery, intake, reservoir, roof catchment, spring, well, and well head. Treatment plant location records were also retained if a PWS had none of the facilities associated with source water. Because there are no NAWQA monitoring stations outside the contiguous 48 States, EPA removed records for Alaska (AK), Hawaii (HI), Puerto Rico (PR), and the Northern Mariana Islands (NMI), resulting in a final dataset of 106,351 facility records for 40,013 CWS. Exhibit 4-2 provides a breakdown of the CWS by system size and Exhibit 4-3 provides a breakdown by source water type. 4-1 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters for the Second Six-Year Review of NPDWRs EPA815-B-09-004 Exhibit 4-1. NAWQA Study Units NAWQA Study Units I | Initiated 1991 I | Initiated 1994 I I Initiated 1997 High Plains Regional Ground Water Study, initiated 1999 NAWQA Study Units 1 Acadian-Pontchartrain Drainages 2 Albemarle-Pamlico Drainage Basin 3 Allegheny and Monongahela River Basins 4 Apalachicola-Chattahoochee-Flint River Basin 5 Central Arizona Basins 6 Central Columbia Plateau 7 Central Nebraska Basins 8 Connecticut, Housatonic, and Thames River Basins 9 Cook Inlet Basin 10 Delaware River Basin 11 Delmarva Peninsula 12 Eastern Iowa Basins 13 Georgia-Florida Coastal Plain 14 Great and Little Miami River Basins 15 Great Salt Lake Basins 16 Hudson River Basin 17 Island of Oahu 18 Kanawha-New River Basins 19 Lake Erie-Lake Saint Clair Drainages 20 Long Island-New Jersey Coastal Drainages 21 Lower Illinois River Basin 22 Lower Susquehanna River Basin 23 Lower Tennessee River Basin 24 Las Vegas Valley Area and the Carson and Truckee River Basins 25 Mississippi Embayment 26 Mobile River Basin 27 New England Coastal Basins 28 Northern Rockies Intermontane Basins 29 Ozark Plateaus 30 Potomac River Basin 31 Puget Sound Basin 32 Red River of the North Basin 33 Rio Grande Valley 34 Sacramento River Basin 35 San Joaquin-Tulare Basins 36 Santa Ana Basin 37 Santee River Basin and Coastal Drainages 38 South-Central Texas 39 South Platte River Basin 40 Southern Florida 41 Trinity River Basin 42 Upper Colorado River Basin 43 Upper Illinois River Basin 44 Upper Mississippi River Basin 45 Upper Snake River Basin 46 Upper Tennessee River Basin 47 Western Lake Michigan Drainages 48 White River Basin 49 Willamette Basin 50 Yakima River Basin 51 Yellowstone River Basin Source: Gilliom, 2006a. 4-2 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters for the Second Six-Year Review of NPDWRs EPA815-B-09-004 Exhibit 4-2. CWS Dataset Summary by System Size Dataset Total CWS with facility location (%) CWS excluding AK, HI, PR, NMI (%) 25 - 500 24,131 (59%) 23,660 (59%) 501- 3,300 10,382 (25%) 10,162 (25%) 3,301 - 10,000 3,492 (9%) 3,414 (9%) 10,001 - 100,000 2,566 (6%) 2,484 (6%) >1 00,000 304 (1%) 293 (1%) Total 40,875 (100%) 40,017 (100%) Source: SDWIS/FED 2007 data extract Exhibit 4-3. CWS Summary by Water Source Dataset Total CWS with facility location (%) CWS excluding AK, HI, PR, NMI (%) GW 36,251 (89%) 35,666 (89%) SW 4,624 (11%) 4,347 (11%) Total 40,875 (100%) 40,013 (100%) Source: SDWIS/FED 2007 data extract GW: ground water, SW: surface water (includes 454 CWS with ground water under the influence of surface water) Using a geographical information system (GIS), EPA estimated the distance between each CWS facility and the nearest NAWQA sampling site. Exhibit 4-4 shows results for 11 distance categories, including the number, cumulative number, and cumulative percent of NAWQA stations in each category. For example, 1,179 or 12.3% of the NAWQA sites are located within 0.5 miles of a CWS facility. Almost half of the NAWQA stations are within three miles of a CWS facility, and over 65% are within five miles. This location analysis does not, however, demonstrate that the water sources monitored by the NAWQA sampling sites are the drinking water sources for the nearest CWS facility; it only demonstrates relative proximity. Exhibit 4-4. Distance from NAWQA Sampling Stations to Nearest CWS Facility Distance in Miles <0.5 0.5-1 1-2 2-3 3-5 5-10 10-15 15-20 20-25 25-50 >50 NAWQA Total 1,179 834 1,456 1,183 1,592 1,642 587 267 172 434 206 Cumulative 1,179 2,013 3,469 4,652 6,244 7,886 8,473 8,740 8,912 9,346 9,552 Cumulative % 12.3% 21.1% 36.3% 48.7% 65.4% 82.6% 88.7% 91.5% 93.3% 97.8% 100.0% 4-3 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters EPA 815-B-09-004 for the Second Six-Year Review of NPDWRs Although many of the NAWQA sampling sites are located within 5 to 10 miles of a CWS facility, the same cannot be said of the CWS facilities. There are approximately 4 times more CWS systems and 10 times more facilities than there are NAWQA sampling sites. 4.2 STORET EPA manages two databases that contain water quality data for waterways in the United States (http://www.epa.gov/storet/). The Legacy Data Center (LDC) contains archived data through the end of 1998, while STORET is an active database updated each month with new water quality data beginning in 1999. It also includes all LDC data. STORET is a repository for data collected by local, state and federal agencies, Indian tribes, universities, and volunteers. Data downloads for a location vary over time as contributors revise their data. It contains raw biological, chemical, and physical data on surface and ground water for all 50 states and U.S. territories and jurisdictions. EPA collected and analyzed all available water quality data for the seven contaminants of interest. 4.3 POP The USD A established the PDF in 1991 to collect data pertaining to pesticide residues in food consumed by infants and children. In 1996, Congress expanded the program to include pesticide residues in drinking water. Implementation of this portion of the program was initiated in 2001. The databases are produced annually and contain the following data collected through December 2006: pesticide residual concentrations in drinking water, bottled water, vegetables, grains, grain products, nuts, dairy products, fruits, poultry, beef, and pork for approximately 372 pesticides results from consumables originating in 43 countries, 50 states, Washington D.C., and Puerto Rico The drinking water data are used to support the Food Quality Protection Act authorized in 1996 by Congress. Sampling occurs in regions of interest for a minimum of two years to track variations throughout different growing seasons. When the study began in 2001, it was limited to treated water at community water systems in New York and California. In 2002, monitoring efforts expanded to include five additional systems in Colorado, Kansas, and Texas; these locations were eliminated after 2003. The study expanded in 2004 to include Michigan, North Carolina, Ohio, Oregon, Pennsylvania, and Washington, as well as add source or raw water samples. Treatment plant personnel collect PDF samples from the raw and treated water flows, attempting to synchronize the collection of samples so that the sample collected after treatment is theoretically from the same aliquot of water sampled at the intake. 4.4 Contaminant Occurrence The following sections discuss the occurrence of six of the seven contaminants of interest, and present summary data (maximum concentration values) from the NAWQA, STORET, and PDF databases. Each summary table juxtaposes the occurrence data with the current MCLG value (or MCL value when it is greater than the MCLG) and one or more possible MCLG values that are based on new health risk information. EPA also plotted the NAWQA data to demonstrate the spatial extent of the sampling locations and occurrence of the contaminants. ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters for the Second Six-Year Review of NPDWRs EPA815-B-09-004 EPA did not identify any readily available water quality data for diquat. The Agency, therefore, obtained available information on diquat use and environmental fate and transport to characterize potential source water occurrence. 4.4.1 Alachlor Exhibit 4-5 and Exhibit 4-6 provide comparisons of the maximum alachlor concentrations found at locations in the NAWQA and STORET databases, respectively, with the current MCL (which is greater than the MCLG) and the possible MCLG value. Exhibit 4-7 presents a spatial representation of the NAWQA data. Less than 0.4% of NAWQA sampling locations have a maximum concentration that exceeds the current MCL and only one has a concentration that exceeds the possible MCLG. STORET data show that less than 1.4% of sampling locations have maximum concentrations above the MCL and none have samples exceeding the possible MCLG. Exhibit 4-8 and Exhibit 4-9 show alachlor raw water concentrations and finished water concentrations, respectively, from the PDF database. None of the samples contained alachlor concentrations that exceeded the current MCL or possible MCLG. Exhibit 4-5. Summary of Alachlor Occurrence Based on Maximum Sample Values for Locations in NAWQA Occurrence Result Total locations All samples are nondetect At least one detection Maximum concentration exceeds current MCL1 (0.002 mg/L) Maximum concentration exceeds possible MCLG (0.04 mg/L) Number of Locations (% of locations) Surface Water 2,125(100.0%) 1,601 (75.3%) 524 (24.7%) 32(1.5%) 1 (0.05 %) Ground Water 6,785 (100.0%) 6,665 (98.2%) 120(1.8%) 2 (0.03%) 0 (0.0%) Other 326(100.0%) 305 (93.6%) 21 (6.4%) 1 (0.31%) 0 (0.0%) Total 9,236(100.0%) 8,571 (92.8%) 665 (7.2%) 35 (0.38%) 1 (0.01%) Source: USGS 2006b (national data from 1992 to 1/1/2008). 1. The current MCLG is zero. Because of analytical limitations, EPA cannot determine the number of samples that do not exceed the current MCLG. Consequently, EPA reports the number exceeding the current MCL, instead of the MCLG. Exhibit 4-6. Summary of Alachlor Occurrence Based on Maximum Sample Values for Locations in STORET Occurrence Result Total locations All samples are nondetects At least one detection Exceeds current MCL1 (0.002 mg/L) Exceeds possible MCLG (0.04 mg/L) Number of Locations (% locations) 2,252 (100.0%) 1,669(74.1%) 583 (25.9%) 40(1.8%) 0 (0.0%) Source: USEPA 2006b (national data 1/1/2002 to 9/20/2006). 1. The current MCLG is zero. Because of analytical limitations, EPA reports the number exceeding the current MCL, instead of the MCLG. 4-5 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters for the Second Six-Year Review of NPDWRs EPA815-B-09-004 Exhibit 4-7. NAWQA Occurrence Data for Alachlor Based on Maximum Sample Values Legend NAWQA Stations Alachlor ° Nondetect Detect - No Exceedance Detect - Exceeds Current MCL Only (0.002 mg/L) Detect - Exceeds Possible MCLG (0,04 mg/L) Exhibit 4-8. Summary of Alachlor Occurrence for Raw Water Samples in USDA Agricultural Marketing Service Pesticide Data Program Occurrence Result Total Samples Nondetect Detected quantity 1 Exceeds current MCL (0.002 mg/L) Exceeds possible MCLG (0.04 mg/L) Number of Samples (% total samples) 1,121 (100%) 1,118(99.73%) 3 (0.27%) 0 (0%) 0 (0%) Source: USDA (2004, 2005, and 2006) Detection limits range from 7.8 X10-6 mg/L to 45 X10-6 mg/L. 1. Detected quantities range from 16.3 X 10~6 mg/L to 44 X 10~6 mg/L. Exhibit 4-9. Summary of Alachlor Occurrence for Finished Water Samples in USDA Agricultural Marketing Service Pesticide Data Program Occurrence Result Total Samples Nondetect Detected quantity 1 Exceeds current MCL (0.002 mg/L) Exceeds possible MCLG (0.04 mg/L) Number of Samples (% total samples) 2,511 (100%) 2,492 (99.24%) 19(0.76%) 0 (0%) 0 (0%) Source: USDA (2001, 2002,2003, 2004, 2005, and 2006). Detection limits range from 5 X10-6 mg/L to 49.5 X10-6 mg/L. 1. Detected quantities range from 16.3 X10-6 mg/L to 145 X10-6 mg/L. 4-6 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters for the Second Six-Year Review of NPDWRs EPA815-B-09-004 4.4.2 Barium Exhibit 4-10 and Exhibit 4-11 provide comparisons of maximum barium concentrations for locations in the NAWQA and STORET databases, respectively, with the current MCLG and possible MCLG values. Exhibit 4-12 presents a spatial representation of the NAWQA data. These data indicate that less than 1% of the total sampling locations for this contaminant have maximum concentrations between the current MCLG and the possible MCLG value. Although barium occurs in detected quantities at most of the NAWQA sampling locations, less than 0.1% of ground water sampling locations and no surface water sampling locations in NAWQA report maximum concentrations above the current MCLG. Likewise, the STORET data indicate less than 0.5% of detections exceed the current MCLG value. Exhibit 4-10. Summary of Barium Occurrence Based on Maximum Sample Values for Locations in NAWQA Occurrence Result Total locations All samples are nondetects At least one detection Exceeds current MCLG (2.0 mg/L) Exceeds possible MCLG (6.0 mg/L) Number of Locations (% of locations) Surface Water 417(100.0%) 1 (0.2%) 416(99.8%) 0 (0.0%) 0 (0.0%) Ground Water 4,326 (100.0%) 42(1.0%) 4,284 (99.0%) 3 (0.07%) 0 (0.0%) Other 121 (100.0%) 0 (0.0%) 121 (100%) 0 (0.0%) 0 (0.0%) Total 4,864(100.0%) 43 (0.9%) 4,821 (99.1%) 3 (0.06%) 0 (0.0%) Source: USGS 2006b (national data from 1992 to 1/1/2008). Exhibit 4-11. Summary of Barium Occurrence Based on Maximum Sample Values for Locations in STORET Occurrence Result Total locations All samples are nondetects At least one detection Exceeds current MCLG (2.0 mg/L) Exceeds possible MCLG (6.0 mg/L) Number of Locations (% locations) 16,595(100.0%) 2,299 (13.9 %) 14,296(86.1%) 234(1.4%) 163(1.0%) Source: USEPA 2006b (national data 1/1/2002 to 9/20/2006). 4-7 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters for the Second Six-Year Review of NPDWRs EPA815-B-09-004 Exhibit 4-12. NAWQA Occurrence Data for Barium Based on Maximum Sample Values Legend NAWQA Stations Barium Nondetect Detect - No Exceedance Detect - Exceeds Current MCLG Only (2.0 mg/L) Detect - Exceeds Possible MCLG (6.0 mg/L) 4.4.3 1,1-Dichloroethylene Exhibit 4-13 and Exhibit 4-14 provide comparisons of maximum 1,1-dichloroethylene concentrations for locations in the NAWQA and STORET databases, respectively, with the current MCLG and possible MCLG values. Exhibit 4-15 presents a spatial representation of the NAWQA data. These data indicate that less than 0.1% of NAWQA locations have maximum concentrations between the current MCLG and the higher possible MCLG values. STORET results indicate higher occurrence frequencies above both the current MCLG and possible MCLG values. The STORET results are driven by the 157 sampling locations in Phoenix, Arizona, that have a maximum sample above the MCL of 0.007 mg/L. Five of these locations also account for those having a maximum sample that exceeds 0.35 mg/L. Exhibit 4-13. Summary of 1,1-Dichloroethylene Occurrence Based on Maximum Sample Values for Locations in NAWQA Occurrence Result Total locations All samples are nondetects At least one detection Exceeds current MCLG (0.007 mg/L) Exceeds possible MCLG (0.35 mg/L) Number of Locations (% of locations) Surface Water 211 (100.0%) 183(86.7%) 28 (13.3%) 1 (0.5%) 0 (0.0%) Ground Water 5,467 (100.0%) 5,346(97.8%) 121 (2.2%) 0 (0.0%) 0 (0.0%) Other 110(100.0%) 107(97.3%) 3 (2.7 %) 0 (0.0%) 0 (0.0%) Total 5,788(100.0%) 5,636 (97.4%) 152(2.6%) 1 (0.02%) 0 (0.0%) Source: USGS 2006b (national data from 1992 to 1/1/2008). 4-8 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters for the Second Six-Year Review of NPDWRs EPA815-B-09-004 Exhibit 4-14. Summary of 1,1-Dichloroethylene Occurrence Based on Maximum Sample Values for Locations in STORET Occurrence Result Total locations All samples are nondetects At least one detection Exceeds current MCLG (0.007mg/L) Exceeds possible MCLG (0.35 mg/L) Number of Locations (% locations) 2,448 (100.0%) 1,498(61.2%) 950 (38.8%) 165(6.7%) 5 (0.2%) Source: USEPA 2006b (national data from 1/1/2002 to 5/1/2007). Note: 97.14% of reported detection limits for the nondetect samples were at or below the current MCLG of 0.007 mg/L and 99.81 % were at or below the possible MCLG of 0.35 mg/L. Exhibit 4-15. Plot of 1-1-Dichloroethylene NAWQA Occurrence Data Legend NAWQA Stations 1,1 -Dichloroethene ° Nondetect Detect - No Exceedance » Detect - Exceeds Current MCLG Only (0.007 mg/L) Detect - Exceeds Possible MCLG (0,35 mg/L) 0 50 500 200 4.4.4 Diquat Water quality results for diquat were not available in either NAWQA or STORET. To characterize potential source water occurrence, EPA obtained pesticide application estimates because diquat's primary uses are as an algaecide, defoliant, desiccant, and herbicide (USEPA, 1995a). There are two sources of national pesticide use: Pesticide Use Database developed by the National Center for Food and Agricultural Policy (NCFAP) in 1997 and CropLife Foundation in 2002 Pesticide Use Maps developed by the USGS for the Pesticide National Synthesis Project. 4-9 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters for the Second Six-Year Review of NPDWRs EPA815-B-09-004 NCFAP estimates indicate overall cropland application of almost 270,000 pounds in 1997, primarily on potato and alfalfa crops (NCFAP, 2000). The NCFAP based these estimates on its own estimates of State-level pesticide diquat application patterns for the period 1994-1998 and State-level crop acreage for 1997 from the USDA Census of Agriculture. The diquat application estimates - annual pounds of active ingredient applied per acre per crop per year - are based on a wide variety of agricultural pesticide survey sources. Thus, the diquat use estimates reflect several limitations: they do not include noncropland applications, the data sources vary in quality, and state-level pesticide use data gaps are filled using data for nearby states. The CropLife Foundation updated NCFAP's analysis to use crop acreage estimates from the 2002 Census of Agriculture and State-level diquat usage patterns based on survey data collected from 1999 through 2004. The annual diquat use estimate is 217,649 pounds (Gianessi and Reigner, 2006). Because the CropLife Foundation study uses the same method as the NCFAP to derive State-level diquat use estimates, the national estimate has similar limitations. More detailed pesticide application data from California indicates the potential for crop usage estimates to understate total diquat use. The State maintains a comprehensive Pesticide Use Reporting (PUR) database. Exhibit 4-16 provides a summary of detailed pesticide application estimates for 2005, which indicate that total diquat use is three times higher than reported crop use. Major non-crop uses include right-of-way (24,521 pounds active ingrediant or Ib a.i.) and landscape (15,689 Ib a.i.) applications. Both of these uses exceeded the two top crop uses: alfalfa for forage (11,138 Ib a.i.) and potatoes (5,104 Ib a.i.). Exhibit 4-16. Crop and Noncrop Diquat Application for California in 2005 Use1 Crop Application Non Crop Application Total Application Pounds 17,375 51,150 68,525 Percent of Total 25% 75% 100% Source: California Pesticide Use Database available at http://pesticideinfo.orq/Detail Chemllse.isp?Rec ld=PC33217#workinq 1. Crop total comprises the following use categories: alfalfa for forage, potatoes, clover for forage, wine grapes, cabbage, and almonds. Non-crop total includes all other use categories. Of the pesticides addressed in this document, diquat has the lowest national estimate for use on crops. Exhibit 4-17 provides national crop use estimates for diquat and the other pesticides included in this report that were developed by Gianessi and Reigner (2006) and provided on-line in an Excel file. These data suggest that even if the actual national use of diquat is several times greater than the crop use estimate indicates, diquat would have one of the lowest annual usage rates in terms of pounds applied. Exhibit 4-17. Estimates of National Annual Pesticide Use for Crops Pesticide Alachlor Diquat Glyphosate Lindane Picloram Annual Pounds 6,269,543 217,649 102,325,419 1,698,309 1,915,653 Type Herbicide Herbicide Herbicide Insecticide Herbicide Source: Gianessi and Reigner (2006) and on-line Excel file at http://www.croplifefoundation.org/cpri npud2002.htm 4-10 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters for the Second Six-Year Review of NPDWRs EPA815-B-09-004 The USGS estimated county-level pesticide usage for 2002 based on crop acreage estimates in the 2002 Census of Agriculture and state-level diquat application rates for the period 1999-2004 developed by the CropLife Foundation (USGS, no date), which implemented the NCFAP method for estimating pesticide usage (Gianessi and Reigner, 2006) and, therefore, has similar limitations. The USGS estimates total diquat application to crops of approximately 200,000 pounds per year, with potatoes accounting for almost 90% of these applications (USGS, no date). Diquat use on crops occurred primarily in regions of New England, the Great Lakes states, North Dakota, the Pacific Northwest, California, and Florida. USEPA (1995a) notes that although diquat is persistent (i.e., it does not hydrolyze and is resistant to degradation), it becomes immobile when it adsorbs to soil particles and, therefore, is not expected to contaminate ground water. Furthermore, diquat dissipates quickly from surface water because it adsorbs to soil sediments, vegetation, and organic matter; the estimated half-life in surface water is 1 to 2 days, based on a study of two ponds in Florida (USEPA, 1995). These factors indicate the possibility of low occurrence in drinking water sources. 4.4.5 Glyphosate Exhibit 4-18 and Exhibit 4-19 provide comparisons of maximum glyphosate concentrations for locations in the NAWQA and STORET databases, respectively, with the current MCLG and possible MCLG values. Exhibit 4-20 presents a spatial representation of the NAWQA data. Although these data are sparse, they indicate that none of the sampling locations for this contaminant have maximum concentrations between the current MCLG and the possible MCLG values. Exhibit 4-18. Summary of Glyphosate Occurrence Based on Maximum Sample Values for Locations in NAWQA Occurrence Result Total locations All samples are nondetects At least one detection Exceeds current MCLG (0.7 mg/L) Exceeds possible MCLG (14.0 mg/L) Number of Locations (% of locations) Surface Water 4(100.0%) 0 (0.0%) 4(100%)2 0 (0.0%) 0 (0.0%) Ground Water 37 (100.0%) 37(100%) 0 (0.0%) 0 (0.0%) 0 (0.0%) Other 0(100.0%) 0 (0.0%) 0 (0.0%) 0 (0.0%) 0 (0.0%) Total 41 (100.0%) 37 (90.2%) 4 (9.8%) 0 (0.0%) 0 (0.0%) Source: USGS 2006b (national data from 1992 to 9/30/2005). Exhibit 4-19. Summary of Glyphosate Occurrence Based on Maximum Sample Values for Locations in STORET Occurrence Result Total locations All samples are nondetects At least one detection Exceeds current MCLG (0.7 mg/L) Exceeds possible MCLG (14.0 mg/L) Number of Locations (% locations) 241 (100.0%) 180(74.7%) 61 (25.3 %) 0 (0.0%) 0 (0.0%) Source: USEPA 2006b (national data from 1/1/2002 to 5/1/2007). 4-11 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters for the Second Six-Year Review of NPDWRs EPA815-B-09-004 Exhibit 4-20. Plot of Glyphosate NAWQA Occurrence Data Legend NAWQA Stations Glyphosate o Nondetect f Detect-No Exceedance ** Detect - Exceeds Current MCLG Only (0.7 mg/L) Detect - Exceeds Possible MCLG (14 mg/L) 4.4.6 Lindane Exhibit 4-21 and Exhibit 4-22 provide comparisons of maximum lindane concentrations for locations in the NAWQA and STORET databases, respectively, with the current MCLG and possible MCLG values. Exhibit 4-23 presents a spatial representation of the NAWQA data. These data indicate that less than 0.1% of NAWQA locations and 0.3% of the STORET locations have maximum concentrations between the current MCLG and the higher possible MCLG values. Exhibit 4-24 and Exhibit 4-25 show lindane raw water concentrations and finished water concentrations, respectively, from the PDF database. No samples contained lindane above the current MCLG or possible MCLG values. Exhibit 4-21. Summary of Lindane Occurrence Based on Maximum Sample Values for Locations in NAWQA Occurrence Result Total locations All samples are nondetects At least one detection Exceeds current MCLG (0.0002 mg/L) Exceeds possible MCLG (0.001 mg/L) Exceeds possible MCLG (0.03 mg/L) Number of Locations (% of locations) Surface Water 1,846(100.0%) 1,718(93.1%) 128(6.9%) 1 (0.05%) 0 (0.0%) 0 (0.0 %) Ground Water 6,127(100.0%) 6,120(99.9%) 7(0.1%) 0 (0.0%) 0 (0.0%) 0 (0.0%) Other 222(100.0%) 220(99.1%) 2 (0.9%) 0 (0.0%) 0 (0.0%) 0 (0.0%) Total 8,195(100.0%) 8,058 (98.3%) 137(1.7%) 1 (0.01%) 0 (0.00%) 0 (0.0%) Source: USGS 2006b (national data from 1992 to 9/30/2005). 4-12 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters for the Second Six-Year Review of NPDWRs EPA815-B-09-004 Exhibit 4-22. Summary of Lindane Occurrence Based on Maximum Sample Values for Locations in STORET Occurrence Result Total locations All samples are nondetects At least one detection Exceeds current MCLG (0.0002 mg/L) Exceeds possible MCLG (0.001 mg/L) Exceeds possible MCLG (0.03 mg/L) Number of Locations (% locations) 2,691 (100.0%) 2,017(75%) 674 (25%) 7 (0.26%) 1 (0.04%) 1 (0.04%) Source: USEPA 2006b (national data from 1/1/2002 to 5/1/2007). Exhibit 4-23. Plot of Lindane NAWQA Occurrence Data Legend NAWQA Stations Lindane ° Nondetect Detect - No Exceedance Detect - Exceeds Current MCLG Only ( 0.0002 mg/L) Detect - Exceeds Possible MCLG (0-001 mg/L) Lower Bound Detect - Exceeds Possible MCLG (0.03 mg/L) Upper Bound Exhibit 4-24. Summary of Lindane Occurrence for Raw Water Samples in USDA Agricultural Marketing Service Pesticide Data Program Occurrence Result Total Samples Nondetect Detected quantity1 Exceeds current MCL (0.0002 mg/L) Exceeds possible MCLG (0.001 mg/L) Exceeds possible MCLG (0.03 mg/L) Number of Samples (% total samples) 1,116(100%) 1,116(100%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) Source: USDA (2004, 2005, 2006). Detection limits range from 10 X10-6 mg/L to 66 X10-6 mg/L. 1. There are no detected quantities. 4-13 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters for the Second Six-Year Review of NPDWRs EPA815-B-09-004 Exhibit 4-25. Summary of Lindane Occurrence for Finished Water Samples in USDA Agricultural Marketing Service Pesticide Data Program Occurrence Result Total Samples Nondetect Detected quantity 1 Exceeds current MCL (0.0002 mg/L) Exceeds possible MCLG (0.001 mg/L) Exceeds possible MCLG (0.03 mg/L) Number of Samples (% total samples) 2,181 (100%) 2,181 (100%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) Source: USDA (2001, 2002,2003, 2004, 2005, 2006). Detection limits range from 10 X1Q-6 mg/L to 66 X1Q-6 mg/L. 1. There are no detected quantities. 4.4.7 Picloram Exhibit 4-26 and Exhibit 4-27 provide comparisons of maximum picloram concentrations for locations in the NAWQA and STORET databases, respectively, with the current MCLG and possible MCLG values. Exhibit 4-28 presents a spatial representation of the NAWQA data. Exhibit 4-29 and Exhibit 4-30 show picloram raw water concentrations and finished water concentrations, respectively, from the PDF database. Data from all three sources indicate no occurrence of this contaminant above the current MCLG and the higher possible MCLG values. Exhibit 4-26. Summary of Picloram Occurrence Based on Maximum Sample Values for Locations in NAWQA Occurrence Result Total locations All samples are nondetects At least one detection Exceeds current MCLG (0.5 mg/L) Exceeds possible MCLG (1.0 mg/L) Number of Locations (% of locations) Surface Water 971 (100.0%) 947 (97.5%) 24 (2.5%) 0 (0.0%) 0 (0.0%) Ground Water 4,603 (100.0%) 4,588 (99.7%) 15(0.3%) 0 (0.0%) 0 (0.0%) Other 198(100.0%) 198(100.0%) 0 (0.0%) 0 (0.0%) 0 (0.0%) Total 5,772(100.0%) 5,733 (99.3%) 39 (0.7%) 0 (0.0%) 0 (0.0%) Source: USGS 2006b (national data from 1992 to 9/30/2005). Exhibit 4-27. Summary of Picloram Occurrence Based on Maximum Sample Values for Locations in STORET Occurrence Result Total locations All samples are nondetects At least one detection Exceeds current MCLG (0.5 mg/L) Exceeds possible MCLG (1.0 mg/L) Number of Locations (% locations) 870(100%) 745 (85.6%) 125(14.4%) 0 (0%) 0 (0%) Source: USEPA 2006b (national data from 1/1/2002 to 5/1/2007). 4-14 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters EPA 815-B-09-004 for the Second Six-Year Review of NPDWRs Exhibit 4-28. Plot of Picloram NAWQA Occurrence Data Legend NAWQA Stations Picloram Nondetect Detect - No Exceedance Detect - Exceeds Current MCLG Only (0.5 mg/L) Detect - Exceeds Possible MCLG (1.0 mg/L) Exhibit 4-29. Summary of Picloram Occurrence for Raw Water Samples in USDA Agricultural Marketing Service Pesticide Data Program Occurrence Result Total Samples Nondetect Detected quantity 1 Exceeds current MCL (0.5 mg/L) Exceeds possible MCLG (1.0 mg/L) Number of Samples (% total samples) 1,122(100%) 1,120(99.82%) 2(0.18%) 0 (0%) 0 (0%) Source: USDA (2004, 2005, 2006). Detection limits range from 22 X1Q-6 mg/L to 4,407 X 10-6mg/L 1. Detected quantity is 37 X 10-6 mg/L. Exhibit 4-30. Summary of Picloram Occurrence for Finished Water Samples in USDA Agricultural Marketing Service Pesticide Data Program Occurrence Result Total Samples Nondetect Detected quantity 1 Exceeds current MCL (0.5 mg/L) Exceeds possible MCLG (1.0 mg/L) Number of Samples (% total samples) 1,876(100%) 1,875(99/95%) 1 (0.05%) 0 (0%) 0 (0%) Source: USDA (2001, 2003,2004, 2005, 2006). Detection limits range from 22 X 1Q-6 mg/L to 5,000 X 1Q-6 mg/L. 1. Detected quantity is 37 X 10-6 mg/L. 4-15 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters for the Second Six-Year Review of NPDWRs EPA815-B-09-004 4.4.8 1,1,1-Trichloroethane Exhibit 4-31 and Exhibit 4-32 provide comparisons of maximum 1,1,1-trichloroethane concentrations for locations in the NAWQA and STORET databases, respectively, with the current MCLG and possible MCLG values. Exhibit 4-33 presents a spatial representation of the NAWQA data. The NAWQA data indicate that none of the sampling locations for this contaminant have maximum concentrations between the current MCLG and the possible MCLG values. Fewer than 0.3% of the STORET locations have maximum concentrations between the current MCLG and the possible MCLG. Exhibit 4-31. Summary of 1,1,1-Trichloroethane Occurrence Based on Maximum Sample Values for Locations in NAWQA Occurrence Result Total locations All samples are nondetects At least one detection Exceeds current MCLG (0.2 mg/L) Exceeds possible MCLG (14 mg/L) Number of Locations (% of locations) Surface Water 210(100.0%) 146(69.5%) 64 (30.5%) 0 (0.0%) 0 (0.0%) Ground Water 5,468 (100.0%) 5,043 (92.2%) 425 (7.8%) 0 (0.0%) 0 (0.0%) Other 110(100.0%) 101 (91.8%) 9 (8.2%) 0 (0.0%) 0 (0.0%) Total 5,788(100.0%) 5,290(91.4%) 498 (8.6%) 0 (0.0%) 0 (0.0%) Source: USGS 2006b (national data from 1992 to 1/1/2008). Exhibit 4-32. Summary of 1,1,1-Trichloroethane Occurrence Based on Maximum Sample Values for Locations in STORET Occurrence Result Total locations All samples are nondetects At least one detection Exceeds current MCLG (0.2 mg/L) Exceeds possible MCLG (14 mg/L) Number of Locations (% locations) 3,429 (100.0%) 2,304 (67.2%) 1,125(32.8%) 5(0.1%) 0 (0.0%) Source: USEPA2006b (national data from 1/1/2002 to 1/1/2008). 4-16 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters EPA 815-B-09-004 for the Second Six-Year Review of NPDWRs Exhibit 4-33. Plot of 1,1,1-Trichloroethane NAWQA Occurrence Data Legend NAWQA Stations 1,1,1-Trichloroethane Nondetect Detect - No Exceedance Detect - Exceeds Current MCLG Only (0.2 mg/L) Detect - Exceeds Possible MCLG (14 mg/L) 4-17 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters EPA 815-B-09-004 for the Second Six-Year Review of NPDWRs 5. Conclusions In this report, EPA addressed contaminants that the Six-Year Review 2 identified as having possible MCLG increases based on new health effects information. A possible MCLG increase and accompanying MCL increase raises the possibility of cost savings among systems treating for the contaminant. The potential for cost savings from possible MCL increases is system- specific and depends on various factors including the magnitude of the MCL increase, the concentration of a contaminant in a system's source water, the specific treatment technology in use, and the extent to which co-occurring contaminants control the operation of a specific technology. Exhibit 5-1 and Exhibit 5-2 present a summary of this information. The new health effects information results in a wide range of possible MCL increases (see Exhibit 5-1). The lowest relative increase is 2 times the current MCL for both diquat and picloram. The highest relative increase is 150 times the current MCL for the upper bound possible MCLG for lindane. EPA's analysis of the potential for cost savings was constrained to readily available data. The data available to characterize contaminant occurrence was especially limited because there is no comprehensive dataset that characterizes source water quality for drinking water systems. Water quality data from the NAWQA Program, STORET data system, and PDF provide useful insights into potential contaminant occurrence in source water, even though they are not based on random or representative sampling events and, therefore, cannot be used directly to derive quantitative estimates of national occurrence in drinking water sources. Nevertheless, the summary of the available data in Exhibit 5-1 shows relatively infrequent contaminant occurrence in potential source waters at the levels of interest. The NAWQA data, which provide the most extensive coverage of potential source waters, indicate that only alachlor is found in concentrations that exceed the possible MCLG. In particular, two contaminants - glyphosate and picloram - are not found at levels above either the current MCLG or the possible MCLG in any of the three datasets. Diquat, which is not included in any of these datasets, has the potential to occur infrequently in source water given its less frequent use compared to the other pesticides in the table (alachlor, glyphosate, lindane, and picloram) and its tendency to dissipate quickly from surface water and be immobile in soils. Without national estimates of contaminant occurrence in drinking water sources, EPA cannot determine how many systems currently treat for the contaminants listed in Exhibit 5-2. EPA also does not have national data regarding the treatment technologies being utilized to control these contaminants. As Exhibit 5-2 shows, some BATs have higher potential for operational cost savings; however, co-occurrence considerations for all of the BATs could diminish the potentially affected system's ability to alter treatment for possible higher MCLGs. Despite the possibility for changes in MCLG values that range from 2 to 150 times higher than current MCLs, the available occurrence data for potential drinking water sources indicate relatively low contaminant occurrence in the concentration ranges of interest. As a consequence, EPA cannot conclude that there is a meaningful opportunity for system cost savings. 5-1 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters for the Second Six-Year Review of NPDWRs EPA815-B-09-004 Exhibit 5-1. Summary of Potential Cost Savings Factors - Occurrence Contaminant Alachlor Barium Diquat Glyphosate 1,1-Dichloroethylene Lindane Picloram 1,1,1-Trichloroethane Magnitude of Increase1 20 3 2 14 50 5 to 150 2 50 Occurrence Summary (percent of sample locations) Exceed Current MCLG or MCL NAWQA 0.38% 0.1% - 0.0% 0.02% 0.01% 0.0% 0.0% STORET 1.8% 1.4% - 0.0% 6.7% 0.26% 0.0% 0.1% POP 0.0% - 0.0% 0.0% -- Exceed Current MCLG or MCL NAWQA 0.01% 0.0% - 0.0% 0.0% 0.0% 0.0% 0.0% STORET 0.0% 1.0% - 0.0% 0.2% 0.04% 0.0% 0.0% POP 0.0% - - - 0.0% 0.0% -- -: No data were available. 1. Number indicates times higher the possible MCLG is than the current MCL. For example the possible MCLG for alachlor (0.04 mg/L) is 20 times higher than the current MCL (0.002 mg/L). Exhibit 5-2. Summary of Potential Cost Savings Factors - Treatment Contaminant Alachlor Barium Diquat Glyphosate 1,1-Dichloroethylene Lindane Picloram 1,1,1-Trichloroethane Best Available Technology Granular Activated Carbon Ion Exchange Lime Softening Reverse Osmosis Electrodialysis Granular Activated Carbon Oxidation (Chlorine or Ozone) Packed Tower Aeration Granular Activated Carbon Granular Activated Carbon Granular Activated Carbon Packed Tower Aeration Granular Activated Carbon Cost Savings Potential of Technology High High Moderate Low Low High Low Low High High High Low High Presence of Co-occurring Contaminants Could Limit Savings Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes 5-2 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters EPA 815-B-09-004 for the Second Six-Year Review of NPDWRs 6. References ATSDR (Agency for Toxic Substances & Disease Registry). 2007. Toxicological Profile for Barium. Available online at: http://www.atsdr.cdc.gov/toxprofiles/tp24.html. August. ATSDR (Agency for Toxic Substances & Disease Registry). 2006. Toxicological Profile for 1,1,1-Trichloroethane. Available online at: http://www.atsdr.cdc.gov/toxprofiles/tp70.html. July. ATSDR (Agency for Toxic Substances & Disease Registry). 2005. Toxicological Profile for Barium. Available online at: http://www.atsdr.cdc.gov/toxprofiles/tp24.html. August. Gianessi, L. and N. Reigner. 2006. Pesticide Use in U.S. Crop Production: 2002 With Comparison to 1992 and 1997 - Fungicides & Herbicides. Washington, D.C.: CropLife Foundation. Gilliom, R.J., I.E. Barbash, C. G. Crawford, P.A. Hamilton, J.D. Martin, N. Nakagaki, L.H. Nowell, J.C. Scott, P.E. Stackelberg, G.P. Thelin, and D.M. Wolock. 2006. The Quality of Our Nation's WatersPesticides in the Nation's Streams and Ground Water, 1992-2001: U.S. Geological Survey Circular 1291. Reston, VA: U.S. Department of the Interior, U.S. Geological Survey. NCFAP (National Center for Food and Agricultural Policy). 2000. Pesticide Use in U.S. Crop Production: 1997. National Summary Report. Washington, D.C.: NCFAP. USEPA. 2009a. Analysis of Occurrence Data from the Second Six-Year Review of Existing National Primary Drinking Water Regulations. EPA 815-B-09-006. USEPA. 2009b. Analytical Feasibility Support Document for the Second Six-Year Review of Existing National Primary Drinking Water Regulations. EPA 815-B-09-003. USEPA. 2009c. Development of Estimated Quantitation Levels for the Second Six-Year Review of National Primary Drinking Water Regulations. EPA 815-B-09-005. USEPA. 2009d. EPA Protocol for the Second Review of Existing National Primary Drinking Water Regulations (Updated). EPA 815-B-09-002. USEPA. 2009e. Six-Year Review 2 - Health Effects Assessment - Summary Report. EPA 822- R-09-006. USEPA. 2009f Water Treatment Technology Feasibility Support Document for Chemical Contaminants for the Second Six-Year Review of National Primary Drinking Water Regulations. EPA815-B-09-007. USEPA. 2009g. Consideration of Other Regulatory Revisions in Support of the Second Six-Year Review of the National Primary Drinking Water Regulations. EPA 815-B-09-008. USEPA. 2008. TRI Explorer - Geographic Report. Online at: http://www.epa.gov/triexplorer/geography.htm?year=2006, accessed March 2008. 6-1 ------- EPA-OGWDW Occurrence Analysis for Potential Source Waters EPA 815-B-09-004 for the Second Six-Year Review of NPDWRs USEPA. 2007. Toxicological Review of 1,1,1-Trichloroethane. Available online at: http://www.epa.gov/ncea/iris/toxreviews/0197-tr.pdf. August. USEPA. 2006a. Drinking Water Contaminants Consumer Fact Sheets. Accessed online at: http://www.epa.gov/OGWDW/hfacts.html. USEPA. 2006b. STORE! Database. Online at http://www.epa.gov/storet/. accessed 9/20/06. USEPA. 2006c. Addendum to the July 2002 Lindane Reregi strati on Eligibility Decision (RED). Available online at: http://www.epa.gov/pesticides/reregistration/REDs/lindane_red_addendum.pdf July. USEPA. 2003. EPA Protocol for Review of Existing National Primary Drinking Water Regulations. EPA 815-R-03-002. June. USEPA. 2002a. Report of the Food Quality Protection Act (FQPA) Tolerance Reassessment Progress and Risk Management Decision (TRED): Diquat Dibromide. Washington, D.C.: USEPA, Prevention, Pesticides and Toxic Substances. USEPA. 2002b. Toxicological Review of 1,1-Dichloroethylene. 2002. Available online at: http://www.epa.gov/NCEA/iris/toxreviews/0039-tr.pdf June. USEPA. 1998. Small System compliance Technology List for the Non-Microbial contaminants Regulated Before 1996. EPA Report 815-R-98-002. Washington, D.C.: USEPA Office of Water. USEPA. 1995a. Reregi strati on Eligibility Decision (RED) Diquat Dibromide. EPA 738-R-05- 016. Available online at: http://www.epa.gov/oppsrrdl/REDs/0288.pdf. July. USEPA. 1995b. Reregi strati on Eligibility Decision (RED) Picloram. Available online at: http://www.epa.gov/oppsrrdl/REDs/0096.pdf August. USEPA. 1993. Reregi strati on Eligibility Decision (RED) Glyphosate. Available online at: http://www.epa.gov/oppsrrdl/REDs/old_reds/glyphosate.pdf September. U.S. Environmental Protection Agency Office of Pesticide Programs (USEPA OPP). 2006. Cumulative Risk from Chloroacetanilide Pesticides. Available online at: http://www.epa.gov/oppsrrdl/cumulative/chloro_cumulative_risk.pdf March. USGS. 2006a. About NAWQA Study Units. December. Accessed online at: http://water.usgs.gov/nawqa/studies/study units.html USGS. 2006b. National Water Quality Assessment (NAWQA) Program. Online at http://infotrek.er.usgs.gov, accessed 8/28/06. USGS. No date. Pesticide National Synthesis Project: 2002 Pesticide Use Map - Diquat (http://water.usgs.gov/nawqa/pnsp/usage/maps/show map.php?vear=02&map=ml950, accessed March 2008). 6-2 ------- |