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HomeMy WebLinkAboutGroundwater Protection Drinking Water Standards by the States 1988Report t.o the Chairman, Subc(munittee (m Hazard(ms '~,astes and I ()x~(' Substan(e., C~munittee on Environment and }Slblic ~ ot ks, [ .S. Senate ,,, ROUNDWATER I'ROTECTION Ill~ Use of Drinking *~*ater Standards by GAO United States General Accounting Office Washington, D.C. 20548 Program Evaluation and Methodology Division B-228844 December 20, 1988 The Honorable Max Baucus Chairman, Subcommittee on Hazardous Wastes and Toxic Substances Committee on Environment and Public Works United States Senate Dear Mr. Chairman: In your letter of January 9, 1986, you requested that we study a number of questions concerning groundwater standards. In our first report in response to your request, Groundwater Quality: State Activities to Guard Against Contaminants (GAO/rEMD-SaS, Feb. 1988), we found, among other things, that when drinking water standards are already available, states that set numeric groundwater standards (with rare exception) applied these drinking water standards as groundwater stan- dards. In our second report, Groundwater Standards: States Need More Information From EPA (GAO/PEMD-SS-6, Mar. 1988), we found that the Environmental Protection Agency does not provide adequate informa- tion to the states to allow the development of technically sound ground- water standards. In your request letter, you also asked that we examine whether SPA drinking water standards are appropriate for use as groundwater stan- dards. We address that issue in this report. We do not take a position on the necessity of uniform national standards to protect groundwater. Results in Brief We found that states continue to use drinking water standards as groundwater standards. However, the appropriateness of doing so is debatable. We found that groundwater quality in 91.8 percent of the locations we studied surpassed drinking water standards for all sub- stances measured. That is a positive result. However, in examining the implications of adopting drinking water standards as groundwater pro- tection standards we found that their adoption would allow the poten- tial for degradation of a considerable amount of groundwater (to the level of contamination allowed by drinking water standards). That is, contaminant levels might gradually increase to about that allowed by the standards. The significance of this finding depends on whether the goal of groundwater protection should be nondegradation or limited deg- radation. The question of which of these goals is appropriate was beyond the scope of this report. Page 1 GAO/PEMD-89-1 Groundwater Protection B-228844 Groundwater has several uses other than for drinking. It is also used for irrigating crops, watering livestock, and supporting aquatic life by serv~ lng as a source of surface water. Drinking water standards are at least as stringent as guidelines published by the National Academy of Sci- ences (~s) for irrigating crops and watering livestock. However, we found that current or anticipated federal drinking water standards of 17 substances are less stringent than guidelines published by Er^ and N^s to protect aquatic life. Therefore, applying these standards to aquifers that replenish particularly sensitive ecosystems could endanger aquatic life. Background We focused on the use of drinking water standards for groundwater pro- tection because of their importance within the groundwater protection framework. The Environmental Protection Agency has established drinking water standards as targets or goals for the prevention and cleanup of groundwater contamination in several programs. Moreover, the information that we gathered in our two previous reports made it clear that standards play a central role in many states' groundwater protection programs and that most states that have numeric ground- water standards base them on federal drinking water standards. Conse- quently, the use of drinking water standards as groundwater standards is a critical feature of groundwater protection programs at the federal and state levels. Er^ has issued, or expects to issue in the near future, 54 drinking water standards; but it does not issue groundwater standards. Drinking water standards are used to ensure that the public water supply is acceptable for drinking and other consumptive uses, whereas groundwater stan- dards are ambient standards and are applied to water in a natural state in the environment. This difference is reflected in findings from our ear- lier studies. For example, we noted that the summary opinion of independent experts and state officials we interviewed was that groundwater protec- tion standards should be based on 12 specific factors: analytical chemis- try, environmental fate, presence of contaminants in groundwater, amount and location of production and disposal of wastes, monitoring methods, technological feasibility of control, human exposure, human health effects, existing guidelines and standards, references for further information, contacts for additional information, and how to use the information. (See GAO/PEMD-88-6 for a more detailed discussion of these Page 2 GAO, PEMI~8~ l Groundwater Protection I~228844 items.) Yet not all factors viewed as important for groundwater protec- tion are appropriate when EPA sets drinking water standards. For exam- ple, environmental fate is not considered when EPA sets drinking water standards. In one of our earlier studies (GAO/rEMS-SS-5), we reported that more than half the state respondents we spoke to told us that drinking water stan- dards "should" or "probably should" be adopted as groundwater stan- dards. EPA does not support the adoption of uniform national groundwater standards. However, we found four programs in which EPA has taken a position on the use of drinking water standards as ground- water standards in localized situations with known contamination sources. In three programs it largely accepts the appropriateness of using drinking water standards as representing an acceptable level of groundwater contamination, and in one it uses drinking water standards as goals for prevention of groundwater contamination. First, through its Groundwater Protection Strategy, EPA has encouraged states to classify aquifers (sources of groundwater) largely according to their suitability as sources of drinking water. Second, the approach used by ~-PA to trig- ger corrective action cleanups of hazardous waste sites under the Resource Conservation and Recovery Act largely relies on maximum contaminant levels (MCLS) for 14 substances. An MCL is a primary drink- ing water standard issued by EPA under authority of the Safe Drinking Water Act. Third, guidelines established by ErA for cleaning up aban- doned hazardous waste sites under the Superfund law also specify applying MCLS "in most situations.'" Finally, in contrast to the positions outlined above, in a recent guidance document the Office of Pesticide Programs argues that steps should be taken to ensure that the concen- tration of pesticides in groundwater does not reach drinking water standard levels. In this "yellow-light, red-light" approach, actions would be taken before contamination reached maximum contaminant levels. More stringent steps would be taken once contamination had reached maximum contaminant levels. An assumption common to all of these policies is that MCLS play a key role in helping to determine the need and scope of regulatory actions, and when coupled with appropriate control techniques and programs, their use will result in an acceptable level of groundwater protection. In this report, we examine this assumption by answering four evaluation questions: ~However, these guidelines allow for more stringent cleanup standards when aquatic life may be harmed by contamination at the maXLraum contanunant level. Page 3 GAO/PEMI)~I Groundwater Protection 1~228844 1. Are states continuing to rely on EPA drinking water standards when setting numeric groundwater standards? 2. How are existing numeric groundwater standards used in state groundwater protection programs? 3. What is the potential for groundwater quality degradation if drinking water standards are used as groundwater protection standards? 4. How do drinking water standards (maximum contaminant levels, in particular) compare to guidelines for protecting uses of groundwater other than for drinking (that is, as a source of water for aquatic life, irrigation, and livestock watering)? We employed a different method for each evaluation question. A com- plete discussion of our methodology is contained in appendix I. Principal Findings States' Reliance on EPA Drinking Water Standards In our first study (GAO/PEMIA88-5), we found that those 26 states that have numeric groudwater standards have relied to a large extent on EPA maximum contaminant levels2 Since we completed our survey of the states for that report in fall 1986, ErA has issued MCLS for eight volatile organic compounds (vocs) for which it had already issued maximum contaminant level goals (I~ICLGS). For five of the eight substances, the MCL and MCLG were set at different levels (with the MCLG being equal to zero). This meant that, for the first time, states had a choice between using MCLS and MCI~S when setting their groundwater standards. (MC~S are set taking into account both health and technological considerations. This is termed a "feasibility-based standard." MCL(;S are set at a level at which there will be no harmful health effects.) To determine whether the reliance on drinking water standards has con- tinued and whether states are relying on MCLGS or some other health- based standard--such as a level associated with an excess risk of cancer Page 4 GAO/PEblI)-89-1 Groundwater Protection B-228844 of one in a million3 --instead of MC~S, we updated the information in this area through a follow-up survey in February 1988. The questionnaire was sent only to those 25 states that we had found to have numeric groundwater standards in our earlier study. (See appendix I for a list of the states; appendix VI contains the questionnaire.) We found that 10 of the 25 states have issued groundwater standards since EPA issued its voc drinking water standards,a All 10 relied on EPA drinking water standards to do so. Of the 15 other states, 10 told us that they plan to rely on EPA drinking water standards should they adopt or revise groundwater standards for the vocs. We also found that 24 of the 25 states would "probably issue groundwater standards for all or most" substances regulated in the future by ErA as drinking water contaminants. It also appears that MCLS will continue to be the standard most often chosen by the states we studied for groundwater standards. As of March 1988, 15 states had either adopted or planned to adopt an MCL as a groundwater standard for at least one of the five substances for which the MCL and MC~G are not equal. Only one state, Idaho, had adopted an Mcr(; as a groundwater standard (for one of the five vocs for which the MCLG is not equal to its MCL), and no state had firm plans to adopt an MCLG in the future. Respondents indicated that the MCL is a more reason- able standard than the MCLG because, in addition to health concerns, it takes into account other concerns such as technological feasibility and enforcement. One problem with using an MCI~ as a groundwater stand- ard is that enforcing a "zero" standard can be seen as unrealistic. For instance, North Carolina sometimes sets groundwater standards at more stringent levels than MCLS. It uses the most stringent of four guideline levels (the MCL, the level associated with a one-in-one-million risk of can- cer, the no observable adverse effect level, and the threshold of taste and odor) rather than the MCLG. Thus, in answer to the first evaluation question, we found that states in our sample continue to rely on EPA drinking water standards when set- ting groundwater standards. Drinking water standards are used both as an indicator of what substances to regulate and as an indicator of the :~This is commonly referred to as a 104 cancer risk. ~Eight other states also have groundwater standards for some or all of the VOCs. However, these standards were issued, or were planned, prior to EPA's promulgating its standards. Four of the remaining seven states an/~lcipate that they will set groundwater standards while the other three are less certain of their future actions. Page 5 GAO/pEMII4igq Groundwater Protection B-228844 level at which to set the groundwater standards. More detailed findings are presented in appendix II. State Use of Groundwater The existence of groundwater standards in and of itself is not enough to Standards guarantee that groundwater will be adequately protected. The effective- ness of groundwater standards depends on how they are used in a number of activities commonly engaged in by states. It is through this use that groundwater standards can play an important role in prevent- ing contamination from occurring and in helping a state to deal with areas that have already been contaminated. For this reason, it is impor- tant to characterize how groundwater standards are used to promote groundwater quality. To address this issue we asked officials of the 25 states with ground- water standards (through the same survey discussed earlier) several questions about their consideration of groundwater protection and their use of groundwater standards in 15 different regulatory activities. We found that of the 15 activities where groundwater protection could be a factor in making decisions, the states, on average, focused on eight activities to a moderate or greater extent: licensing or permitting surface discharges, setting effluent limits, requiring designs for waste disposal facilities, requiring designs for bulk storage facilities, licensing well drillers, controlling the siting and installing of wells, requiring adher- ence to aquifer recharge standards, and containing or cleaning up haz- ardous waste sites. We then evaluated, for each of these eight activities, the extent to which groundwater standards were used, on average, by those states that had considered groundwater protection to at least a moderate extent. We found that groundwater standards were used to a moderate or greater extent in five of the eight activities: licensing or permitting surface dis- charges, setting effluent limits, requiring designs for waste disposal facilities, requiring adherence to aquifer recharge standards, and con- raining or cleaning up hazardous waste sites. These findings thus describe the major ways in which groundwater standards are used, in answer to our second evaluation question. A more detailed discussion is presented in appendix III. B-228844 Drinking Water Standards and Potential Degradation of Groundwater We used data from the U.S. Geological Survey's (us~s) WA~S~ORE data base to determine whether the use of MCLS, MCL6S, and levels associated with a one-in-one-million risk of cancer would ensure nondegradation of groundwater resources. We accessed these data from ~P^'s water data base, STORET. The question we examined should not be construed to imply that ~rA or the states depend solely upon ambient standards to control groundwater contamination. In fact, EPA and the states have provisions for other reg- ulatory mechanisms, such as source controls, to manage contamination of groundwater resources. These programs are aimed at limiting the migration of contamination from specific pollution sources into the envi- ronment. However, because of the inherent nature of standards as limit- ing values and the incomplete protection afforded by source controls, there is a potential for allowing degradation to occur to the standards' levels under an approach employing ambient standards and source controls. The groundwater quality data were collected between 1976 and 1987. The data base contained information on 43 of the 54 substances for which EPA has issued drinking water standards or, according to ~PA offi- cials, will be issuing new or revised standards in the near future? Several of the 42 substances are present in groundwater from natural sources as well as through introduction by man. We are unable to deter~ mine how much of the contamination at sites we studied is due to natu- ral sources. As used in this context "contamination" denotes pollution from natural sources as well as from human activities. To analyze the data, we divided the country into one-square-mile "cells," each containing from 0 to 114 wells at which the usc-s had conducted chemical analyses. We then used the most recent measurement for each substance from all the wells in each cell. We found that one or more substances had been measured in 12,072 cells out of a potential 3.6 mil- lion in the United States. The data from these cells are not a random sample of the nation's groundwater and cannot be used to develop a quantitative portrayal of Page 7 GAO/PEMI~8~I GroundwaZer Pro~ection 1~2~8844 groundwater quality throughout the nation. However, according to offi- cials at usc-s, the data are the most comprehensive validated data on groundwater quality that exist. The strengths and limitations of the data set and our analytic methodology are discussed in appendix I. How- ever, one point should be made here. According to officials at the Geo- logical Survey, much of the data contained in its W^TSTORE data base were collected in response to perceived pollution problems. Therefore, the contaminant levels in the uSGS wells will tend to be high and our findings very likely underestimate the percentage of groundwater that could be degraded in the nation as a whole if pollution levels were allowed to increase to the level of the drinking water standards. The implications of this for our conclusions are discussed in appendix IV. We used the USGS data set to compare the concentration in groundwater of drinking water contaminants to drinking water MCLS and other guide- lines. Of the 12,072 cells in our study, 91.8 percent had groundwater that met EPA maximum contaminant levels if those standards were applied by the states.~ Approximately 85 percent of the time, it was con- tamination by heavy metals and bacteria that exceeded the MCL level (850 cells exceeded one or more inorganic compounds, 22 cells exceeded one or more pesticides, 135 ceils exceeded one or more nonpesticidal organic compounds). When we compared the latest reading at each cell against EPA'S MCLGS, we found that 71 percent of the cells met the MCLG standard (for most of the 42 substances, the MCL is equal to the MCLG)? We also compared the latest reading at each cell against a third set of guidelines for the 13 (out of 42) contaminants that EPA has identified as causing cancer in humans: a level associated with a one-in-one-million risk of cancer. Measurements at 42.5 percent of the cells met the guideline level associated with a one- in-one-million risk of cancer for one or more of the 13 substances, whereas 96.4 percent met MCLS and 9.1 percent met MCLGS for one or more of the 13. Therefore, in answer to our third question we found, using the USGS data set, that approximately 92 percent of the cells met the standard limits if MCLS are adopted as groundwater protection standards. If MCLGs are adopted, 71 percent met the standard limits. In addition, approximately taken of every substance. 7An MCLG could not be ssalgned for 3 of the 42 substances, and m these cases we employed the MCI.. Restricting our analysis to the 39 would change the findings from 71.0 percent to 7 t.3 percent K228844 43 percent of the cells met a limit associated with a one-in-one-million risk of cancer for one or more of 13 carcinogens. Adopting any of these standards or guidelines as groundwater standards would potentially allow for degradation of the nation's groundwater resources because contaminants could be aliowed to increase to the maximum concentra- tions allowed by the standards. Again, these numerical findings cannot be generalized nationally because the data set was not randomly con- structed with respect to the nation's groundwater resources. More detailed findings about the relationship of groundwater quality to these guidelines is presented in appendix IV. Comparison With Other Uses of Groundwater Groundwater has several uses besides drinking. It is used to irrigate crops and water livestock. It affects the habitat of aquatic life because it flows into bodies of surface water. Applying drinking water standards to groundwater could jeopardize other uses that require standards higher than those for drinking. We compared EPa maximum contaminant levels with guidelines for other uses published separately by EPa and the National Academy of Sciences. We found that EPA maximum contami- nant levels are at least as stringent as all published guidelines for live- stock watering and irrigation and therefore would protect these uses. However, we found that the ~lc~s for 17 substances are less stringent than EPA and NAS aquatic life guidelines and therefore would not always protect aquatic life. Using the same techniques outlined in the previous section, we examined how often the cells exceeded the more stringent of the MCLS and aquatic life guidelines. Whereas we had found earlier that 91.8 per- cent of the cells met the MCL8, we next found that when the aquatic life guidelines are substituted for the MCLS (for those substances that have an aquatic life guideline that is more stringent than its MCL), 66.9 per- cent of the cells met the recommended levels. A decision to apply ErA maximum contaminant levels as groundwater standards, without allowing for greater stringency when local conditions warrant it (such as in ecosystems that are sensitive to these particular substances or that are in areas of high groundwater recharge with low surface water dilu- tion) could jeopardize sensitive species of aquatic life. More detailed findings can be found in appendix V. Agency Comments We received written comments on this report from the Environmental Protection Agency after the 30 calendar days specified by law; there- fore, they have not been reproduced in the report. However, we did Page 9 GAO/PEM~SK1 Groundwater Pro~eeUon B-228844 obtain informal comments in time to incorporate them into our report where appropriate. As agreed with your office, unless you publicly announce its contents earlier, we plan no further distribution of this report until after its issue date. At that time, we will send copies to the Administrator of the Envi- ronmental Protection Agency, to interested organizations, and to others upon request. If you have any questions or would like additional infor- mation, please call me at 202-275-1854. This report was prepared under the direction of Michael J. Wargo, Asso- ciate Director. Other major contributors are listed in appendix VII. Sincerely yours, Eleanor Chelimsky Page 10 Page 11 GAO/PEM]~8~I Groundwater Protection Contents Letter Appendix I Objective, Scope, Methodology Appendix II State Groundwater Standards Appendix III Use of Groundwater Standards Appendix IV Potential Degradation of Groundwater Appendix V Comparison of Guidelines for Groundwater Uses Appendix VI Questionnaire Appendix VII Major Contributors to This Report Objective Scope and Methodology Background Findings Summary and Conclusions Findings Summary Background Findings Summary and Conclusions Background Findings Summary and Conclusions Program Evaluation and Methodology Division 14 14 14 19 19 19 23 24 24 27 28 28 32 38 39 39 39 42 43 51 51 Pagel2 GAO/PI~dD4~I Groundwater Protection Glossary Related GAO Products Tables Figures Table II.l: Current or Expected Levels of State VOC Standards For Selected Substances Table II.2: Number of States With Groundwater Standards for Volatile Organic Compounds Table III. 1: Application of Groundwater Standards Table III.2: Responses to Violations of Groundwater Standards Table IV.l: EPA Drinking Water Standards Set and Anticipated Table IV.2: Cells Exceeding Maximum Contaminant Levels Table IV.3: Cells With One or More Sites Exceeding MCLs and MCLGs Table IV.4: Cells With One or More Sites Exceeding MCLs for Current and Anticipated Standards Table V.I: Comparison of Standards for Various Uses of Groundwater Figure III.h Extent Groundwater Protection Is Considered in 15 Activities Figure III.2: Extent Groundwater Standards Are Used in Eight Activities Figure IV. 1: Distribution of Wells Used in This Study 52 53 20 22 26 27 29 33 34 36 4O 24 25 31 Abbreviations ErA Environmental Protection Agency 6^o General Accounting Office MCL Maximum contaminant level MCL~ Maximum contaminant level goal NAS National Academy of Sciences STORET Storage and retrieval data base us(;s U.S. Geological Survey voc Volatile organic compound WATSTORE Water Data Storage and Retrieval System Page 13 GAO/PEMn-89-1 Groundwater Protect/on Appendix I Objective, Scope, Methodology Objective We were asked by Senator Max Baucus to determine whether drinking water standards are directly appropriate as groundwater standards. To answer this question we formulated four evaluation questions: 1. Are states continuing to rely on EPA drinking water standards when setting numeric groundwater standards? 2. How are existing numeric groundwater standards used in state groundwater protection programs? 3. What is the potential for groundwater quality degradation if drinking water standards are used as groundwater protection standards'? 4. How do drinking water standards (maximum contaminant levels (MCLS), in particular) compare to guidelines for protecting uses of groundwater other than for drinking (that is, as a source of water for aquatic life, irrigation, and livestock watering)? Scope and Methodology States' Reliance on and Use of EPA Standards The scope and methodology used to address each evaluation question varied. We based our work for the first two evaluation questions on a survey sent to the 25 states that had numeric groundwater protection standards as of fall 1986. Those states are Alaska, Arizona, California. Colorado, Florida, Georgia, Idaho, Illinois, Maine, Maryland, Massachu- setts, Minnesota, Missouri, Montana, Nebraska, New Hampshire, New Jersey, New Mexico, New York, North Carolina, Oklahoma, South Caro- lina, Virginia, Wisconsin, and Wyoming. The results from the survey were published in 1988.~ Then in 1988 we conducted structured interviews with representatives of the same 25 states. In February, we sent a questionnaire to one respondent in each of these states. (See appendix VI.) We acquired answers to the questionnaire through telephone interviews with respon- dents in all 25 states. When our respondent could not provide all of the information that we needed, we asked for the names of other officials t See GroLmd~vater Quality: State Activities to Guard .~,ainst Contaminants (GAO., PEMD-88-5. Feb. 1988). Page 14 Appendix I Objective, Seo~, Methodology who could provide the information and then obtained it from them. The number of responses varied for each questionnaire because of differ- ences in state programs and nonrespouses. We asked follow-up ques- tions through July 1988. We used this approach of combining mailed questionnaires with follow- up telephone interviewing because it has the advantages of both meth- ods. That is, each respondent had an opportunity to consider the ques- tions before responding, unlike conventional telephone interviews. And, we had the flexibility to answer the respondent's questions, to clear up misunderstandings, and when appropriate, to gather additional informa- tion not directly requested in the questionnaire we had mailed. The principal focus of the 1988 survey was to identify states' actions to set grotmdwater standards for eight volatile organic compounds (vocs) for which EPA had issued maximum contaminant levels and maximum contaminant level goals (MCI~S) after we had completed our 1986 sur- vey. We also asked about the states' plans for issuing further grotmd- water standards and their use of groundwater standards. For the first evaluation question, we focused on the quantitative level of the states' groundwater standards. We categorized states according to how their standards compared to ErA maximum contaminant levels and MC~GS for volatile organic compounds. The five categories were: equal to the MCL, equal to the MCI~, more stringent than the MCL but not equal to the MCm, less stringent than the MCL, and no standard. Our analysis con- sisted of calculating for each substance its frequency of occurrence across the states in each category. We were also able to classify the states by their expected reliance on E?A standards in the future. We did this by seeking information on their expected response to E?A'S issuance of further drinking water standards (issue groundwater standards at the MCL level, issue standards at the MCIZ; level, issue standards at the MCL or MCLG level, issue standards but not necessarily at the MCL or MCLG level, and undecided as to whether standards would be issued). We then calculated the frequencies of the possible responses. To address the second evaluation question, we concentrated on 15 activ- ities commonly engaged in by state governments for which groundwater protection could be a consideration. We asked each respondent to indi- cate the extent to which groundwater protection is a consideration in their state in each of these activities. If the respondent answered that groundwater protection is considered to at least "some extent," we then Page 15 GAO/PEMD-8~I Groundwater Protection Appendix I ObjecUve, Scope, Methodology asked the extent to which groundwater standards are used in that activ- ity. Both sets of responses were on a five-point scale ranging from "little or no extent" to "a very great extent." We calculated the mean response over ail 25 states for each activity. We then computed the mean response to the "use of standards" question for those states that answered "a moderate extent," or greater. Drinking Water Standards and Potential Degradation of Groundwater The third evaluation question pertains to how groundwater quality com- pares to standards in all 50 states for contaminants for which E?^ has issued or expects to issue drinking water standards (MCLS and MCLGS). We accessed groundwater data from EPA'S water quality data base, S~ORET (storage and retrieval). The Er^ data base contains information about wells from which groundwater contamination is determined: the location of the well (in latitude and longitude), the concentration of mea- sured substances and the date each reading was taken. Rather than analyze all of the groundwater data in the STORET data base, we confined our analysis to data that are contributed to STORET from the U.S. Geological Survey's (usGs) WATSTORE data base. We chose to analyze only data gathered at these wells for several reasons. USGS is the princi~ pal federal water data agency. Sixty percent of all wells used as sources of information for the STORET data base are part of the WATSTORE data base. Moreover, these data have a broad geographical breadth (we found uscs groundwater data for 48 of the 50 states). Although we can- not use the data base to generalize about the nation's groundwater qual- ity (for reasons discussed below), our conclusions are based upon a large and varied set of sites. In addition, the quality assurance methods USGS Uses make us more confident of the validity of its data than of some of the other groundwater data contained in the STORET data base. Whereas we were told that the groundwater quality data gathered and analyzed by usgs "are generally of high quality," according to an E?^ document, much of the other groundwater data in STORET are of "uncertain qual- ity.'' We did not independently review the validity of the data we used. The usgs data came from a variety of networks and projects and were collected for a variety of purposes. According to officials at the Geologi- cal Survey, much of the data contained in the data base were collected by usgs in response to perceived pollution problems. Therefore, our find- ings very likely underestimate the percentage of groundwater that could be degraded in the nation as a whole if drinking water standards ~vere used as groundwater standards. The implications of this for our conclu- sions are discussed in appendix IV. Page 16 GAO ,'PEMD-S9-! Grotmdwater Protection Appendix I Objective, Scope, Methodology We restricted our analysis to data collected between January 1, 1976, and December 31, 1987. us~s had groundwater quality data for 43 of the 54 drinking water substances, and we limited our analysis to 42.3 We found that one or more of them had been measured at 23,021 wells over the 12-year period. In some geographical areas, there is a heavy clustering of sampled wells (typically because the usgs engaged in a detailed study related to known or suspected contamination). To reduce the distorting effect that the clustering would have on our findings, we grouped together wells that were in close proximity. We did this by dividing the entire country into approximately 3.6 million one-square-mile cells. Using latitude and lon- gitude readings to demarcate its location, we assigned each of the 23,021 sampled wells to its appropriate cell. The cell was our unit of analysis. We found 12,072 cells in the United States in which one or more wells had measurements for one or more of the 42 substances.~ We used the most recent measurement for each substance from all sites in the cell. As would be expected, the data we analyzed are not uniformly distrib- uted by geographical location. There were no sites in two states, Ver- mont and West Virginia, yet we found 3,764 cells with wells in South Dakota. In addition to this variation in geographical location, we found a large degree of variation in the number of cells in which the 42 sub- stances were measured. For example, whereas several metals were mea- sured in more than 5,000 cells, aldicarb was measured in only four cells. Also, the number of substances measured in each cell varied. Between one and six substances were measured in about 62 percent of the cells. Fifteen or more substances were measured in approximately 2,000 of the 12,072 ceils. We analyzed the data by writing computer programs to compare each measurement for each of the 42 substances against its MCL and MCLG. For ~Turbidi~y is one of ~he drinking water standards set by EPA. However, we did not include turbidity ~ one of the standards we examined since it can be ~ artifact caused by t~be water testing process rather ~han a true indicator of groundwater contamination. As a result, our analysis wos of 42, no~ 43 3Although approximately 9,000 cel~s had only one well, several cells had a large number of wells. We found one cell on Cape Cod with 114 wells. Page 17 GAO/PEMD-89-I Groundwater Protection Apl~ndix I Objeetive, Scope, Methodolog~ those 13 substances that EPA has identified as causing cancer, we com- pared each measurement to the level associated with a one-in-one-mil- lion risk of cancer.4 We provide information on the number and percentage of cells that could be potentially degraded should drinking water standards be adopted as groundwater protection standards. In addition, we present detailed information in appendix IV on the number and percentage of ceils at which contamination concentration levels exceeded (were greater than) the drinking water standards (see tables IV.2, IV.3 and IV.4). Comparison With Guidelines for Other Uses of Groundwater For the final evaluation question, we examined the 54 contaminants for which standards have been issued or anticipated. We compared EPA drinking water standards with consensus documents published sepa- rately by EPA and the National Academy of Sciences. These documents give maximum recommended contaminant levels for groundwater that is to be used by aquatic life and for irrigation and livestock watering. There were recommended aquatic life guidelines for 29 of the 54 drink- lng water substances. There were 10 guidelines for livestock watering and eight for irrigation. We compared these recommended levels to ErA'S maximum contaminant levels. We also used the USGS groundwater data base to examine how often the "cells" exceeded either the aquatic life guidelines or the MCLS. When there was no aquatic life guideline or the MCL was more stringent than the aquatic life guideline, the measured cell value was compared to the MCL. Otherwise, the measured value was compared to the guideline. Our review was conducted in accordance with generally accepted gov- ernment auditing standards. Page 18 GAO/PFAMI)-89-1 Groundwater Protection Appendix II State Groundwater Standards Our first evaluation question is: "Are states continuing to rely on EPA drinking water standards when setting numeric groundwater stan- dards?'' The findings from a questionnaire we administered to the 25 states that have numeric groundwater standards are detailed below. Background In our report (GAO/Pam)-SS-5) based on interviews conducted in fail 1986, we found that 26 states had numeric groundwater standards. In addi- tion, we found that states relied heavily on EPA drinking water stan- dards when setting groundwater standards. In summer 1987, EPA issued drinking water standards for eight volatile organic compounds (vocs). The following spring, we revisited 25 of these states to determine whether their reliance on rrA drinking water standards as a basis for groundwater standards had continued, both in general and for the vocs in particular.~ Findings Drinking is viewed by the state respondents as the most important use of groundwater. Nineteen of 20 respondents indicated that drinking water considerations greatly influenced the level at which they set groundwater standards. Twenty-four of the 25 states either had groundwater standards for one or more of the vocs prior to EPA'S issuance of standards or have adopted or plan to adopt standards for one or more of the vocs as a result of EPA'S actions, State reliance on EPA drinking water standards for groundwater protec- tion continues. Twenty states (80 percent) either have adopted EPA'S VOC drinking water standards as groundwater protection standards or say that if they revise existing standards or issue new ones, they will use ErA maximum contaminant levels or MCL goals. EPA maximum contaminant levels provide a baseline in terms of protec* tion. Of the 23 states that could characterize their current or expected groundwater standards for the vocs, only one (New Mexico) had the majority of its standards set at a level less stringent than the MCL. The New Mexico standards were established prior to EPA'S issuance of drink- ing water standards for the vocs. The respondent indicated that any revisions to its standards would probably be based on ErA standards. ~As noted on p. 4, we did not include Texas in this particular evaluation. Page IS GAO/PEMI~8~I Groundwater Protection ~p~d~ H For the volatile organic compounds, the states we surveyed have relied or plan to rely on MCLS, not MCL6S (see tables II.l and II.2). Table I1.1: Current or Expected Levela of State VOC Standards For Selected Sub~tanneaa Stete Benzene CaC~on tet~echle~le Pera-~zene~ Alaska MCL MCL MCL/MCLG Arizona MCL MCL MCL/MCLG California MCL MCL MCL/MCLG Colorado MCL MCL MCL/MCLG Florida Other (M) Other (M) None Georgia MCL MCL MCL/MCLG Idaho None None None Maine MCL MCL MCL/MCLG MaryLand MCL MCL MCL/MCLG Massachusetts MCL MCL MCL/MCLG Minnesota~ Missouri Other (L) Other (M) Nor~e Montana MCL MCL MCL/~CLG Nebraska MCL MCL MCL/MCLG New Hampshire MCL MCL MCL/MCLG New Jersey Other (M) Other (M) Other (M) New Mexico Other (L) Other (L) None New York Other (M) MCLc Other (M) North Carolina Other (M) Other (M) Other (M) Oklahoma Other (M) Other (M} None South Carolina MCL MCL MCL/MCLG Virginia~ MCL/MCLG MCL/MCLG MCL/MCLG W~sconsin Other (M) None Other Wyoming MCL None None Page 20 GAO/PEMl)-89-1 Grotmdwater ProtecClon Appendix H State Grou~dwa~r Standards 1,2-dichloroethane 1,1-dichloroethyleneb 1,1,1-trlchloroethaneb Tdchloroethylene Vinyl chloride MCL MCL/MCLG MCL/MCLG MCL MCL MCL MCL/MCLG MCL/MCLG MCL MCL MCL MCL/MCLG MCL/MCLG MCL MCL MCL MCL/MCLG MCL/MCLG MCL MCL Other (M) None MCL/MCLGc Other (M) Other (M) MCL MCL/MCLG MCL/MCLG MCL MCL None None None MCLG None MCL MCL/MCLG MCL/MCLG MCL MCL MCL MCL/MCLG MCL/MCLG MCL MCL MCL MCL/MCLG Other (M) Other (M) MCL Other (M) MCL/MCLG MCL/MCLG Other (M) MCL MCL MCL/MCLG MCL/MCLG MCL MCL MCL MCL/MCLG MCL/MCLG MCL MCL MCI MCL/MCLG MCL/MCLG MCL MCI. Other (M) Other (M) Other (M) Other (M) Other (L) Other (L) Other (M) Other (M) Other (L) Other (M) Other (M) Other (M) Other (M) Other (L) Other (L) Other (M) MCL/MCLG MCL/MCLG Other (M) Other (M) Other (M) Other (M) Other (M) Other (M) Other (M) MCL MCL/MCLG MCL/MCLG MCL MCL MCL/MCLG MCL/MCLG MCL/MCLG MCL/MCLG MCL/MCLG Other (M) Other (M) MCL/MCLG Other (M) Other (M) None None None MCL None ~Other {M) = more stringent than MCL; Other (L) = less stringent than MCL bFor this sul~stance, the MCL is equal Io the MCLG. CThis standard is equal to the MCL or the MCLG by coincidence. ~lllinois and Minnesota have not yet decided at what levels their standards wdl be set, eVirgin~a has not yet decided whether to adopt MCLs, MCLGs, or some combination. Page 21 GAO/PEMD-89-1 Groundwater Prote~lon Appendix H State Groundwater Standards Table 11.2: Number of States With Groundwater Standards for Volatile Organic Compounds' Substance MCL MCLG Other (M)b Other (L)b None Benzene 13 0 6 2 1 Carbon tetrechloride 13c 0 5 1 3 Para-dichlorobenzene 12 J 3 1 6 1,2-dichloroethane 12 0 7 1 2 1,1-dichloroethylene 14 "¢ 5 0 3 1,1, 1-tricholoroethane 15~ :~ 5 0 2 0 Trichloroethylene 12 1 7 2 Vinyl chloride 13c 0 - 5 2 ~ ~l~linois, Minnesota, and Virgima are not ~ncluded ~n this ~ab~e because ~heir plans at ~he t,me of the ~nterview were uncertain ~Other {Mi = more stringent than MCL; Other IL) = less stnngent than MOL COne of these cases is equal to the MCL b~, ce~nc~dence. eThe MCL aha MCLG are equal for ~his substance COne of these cases ~s equa~ to the MCL and MCLG by coincidence Of the 10 states (Arizona, Colorado, Georgia, Idaho, Maryland, Mas- sachussetts, Missouri, Nebraska, New Hampshire, Wyoming) that have set groundwater standards for one or more of the vocs since EPA issued its drinking water standards, only Idaho has adopted an MCLG (for one substance) when the MCL and MCLG were not equal. The other nine have used MCLS. Seven (Arizona, Colorado, Georgia, Maryland, Nebraska, New Hampshire, Wyoming) have used MCLS for all the vocs they regulated. Four states anticipate that they will set groundwater standards for the vocs. Three of them (California, Montana, South Carolina) expect to set their standards at the MCL level for all eight substances. The fourth state (Virginia) has not yet decided whether to adopt MCUS, MCLGs, or some combination. Three other states are less certain of their future actions. Two of these (Alaska, Maine) indicated that if they do adopt voc standards, they will most likely be set at the MCL level. The third state (Minnesota) does not expect to issue standards based on the MCLS and is uncertain if it will use the MCLG. The other eight states (Florida, Illinois, New Jersey, New Mexico, New York, North Carolina, Oklahoma, Wisconsin) had or were in the process of establishing groundwater standards for some or all of the v~:~:s when Page22 GAO,, PEMD~{~I Groundwater Protection Appendix n Stat~ Groundwater Standards EPA set its drinking water standards. Four of these states (Florida, Illi- nois, New Mexico, Wisconsin) expect to use the EPA drinking water stan- dards should they adopt new, or revise existing, voc groundwater standards. States will continue to rely on EPA drinking water standards in the future. Twenty-four of 25 state respondents said that if ErA promulgates additional drinking water standards, then their states will most likely issue groundwater standards for previously unregulated contaminants or will revise existing standards for those substances already regulated. Thirteen of the 24 states will probably set standards at the EPA level (MCL or MCL6). The other 11 states would not necessarily set their groundwater standards at the MCL or MCLG. Summary and Conclusions The 25 states that had established numeric groundwater standards as of fall 19S6 have continued to rely heavily on ErA drinking water stan- dards when setting additional groundwater standards. With EPA'S issu- ance of MCLS and MCL(~s for eight volatile organic compounds last spring, states were, for the first time, able to choose between using a purely heaith-based criterion (MC~(~) and a feasibility-dependent criterion (MCL) when setting groundwater standards. When presented with this choice, states have based their groundwater standards on MCLS. The implication of this, along with the respondents' contention that their states will con- tinue to rely on ErA drinking water standards, is that the states' depen- dence on MCLS for setting groundwater standards will continue. Page 23 GAO/PEMn~89-1 Groundwater Protection Appendix III Use of Groundwater Standards Our second evaluation question was: "How are existing numeric ground- water standards used in state groundwater protection programs?" The findings from our survey of the 25 states that have numeric ground- water standards are detailed below. Findings Among the 25 states, groundwater protection has been considered to at least a moderate extent (on average) in eight of 15 activities in which protection could be a factor in decision-making (see figure III. 1). Figure ILL1: Extent Groundwater Protection I~ Con~lde~d in 15 Activities (1) (2) (S) (4) (5) I .... ~ .... I .... I~,,,I .... [ (2~) Note: Dots represent the average response from the state respondents The numbers ~n parentheses indicate the number of responses for that achvity. Page 24 GAO/P~I Groundwater Proteerlon Appendix I]I Use of'Groundwater Standard~ For each of the eight activities, we calculated the average use of stan- dards by those states that considered groundwater protection to at least a moderate extent. Groundwater standards were used to a moderate or greater extent in five of the eight activities (see figure III.2). Figure 111.2: Extent Groundwater Standarde Are Used in Eight Activities No Extent Extent Extent Extent Qr~t Extent (t) (2) (5) (4) (5) ! .... ) .... I~,,,' .... I .... ~ .... I .... ~ .... I (15) Zoning (') ~:lulrlno pro~rW right8 (')~ Note: Results are displayed for the eight act~vihes ~n which groundwater protection was considered to at least a moderate extent Activihes marked with an asterisk did not meet this criterion. Dots represent the average response from the state respondents The numbers in parentheses indicate the number of responses for that activity Page 25 GAO/PEMl~89-1 Groundwater Protection Appendkx HI Use of Groundwater Standards Twenty of the 25 states have used standards to estimate the impact of proposed activities on groundwater quality. This predictive application of standards is shown in table III. 1. Some states used formal analytical techniques to assess alternatives; others, less formal. Also shown in table III.1 are the 17 states that have used standards as part of monitor- ing requirements to assess the impact of regulated actions on ground- water quality. Where they have identified violations of groundwater standards, states have responded by shutting down operations, restrict- ing operations, monitoring for further violations, or cleaning up contam- inated aquifers (see table III.2). Table II1.1: Application of Groundwater Standards State' Predictive Formal LeMi formal Monitoring Alaska Arizona California Colorado Florida Georgia idaho Illinois Maine Maryland Massachusetts Minnesota Missouri Montana Nebraska New Hampshire New Jersey New Mexico New York North Carolina Oklahoma South Carolina Virginia Wmconsin Total 12 19 17 ~States with empty cells did not use the standard Of the 25 stales. W¥om,n§ d,d nol pro,,,~de ~nform5 t~on In this area. Page 26 GAO,'PEMD~Sg-I Grotmdwater Protection Appendl~ III Use of Groundwater Standards Table 111.2: Responsee to Violations of Groundwater Standards Shut down Restrict Monitor Clean State" operation operation operation aquifer Alaska Arizona - Colorado Florida Georgia Idaho Illinois Maine Maryland Massachusetts Minnesota Missouri Montana Nebraska New Hampshire New Jersey New Mexico New York North Carolina South Carolina Virginia Wisconsin Wyoming Total 15 20 23 21 ~California and Oklahoma were not asked to provide information in this area because they do not have statewide groundwaler standards for any of the 22 substances with primary drinking water standards, Summary Within their regulatory programs, 25 states have used standards in sev- eral activities where groundwater contamination needs to be considered. They used the standards to estimate the impact of proposed activities on groundwater quality, to monitor groundwater quality, and to perform investigatory and remedial activities. Page 27 GAO/PEMD-89-1 Groundwater Protection Appendix IV Potential Degradation of Groundwater Background Our third evaluation question was: "What is the potential for ground- water quality degradation if drinking water standards are used as groundwater protection standards?" Detailed findings for this question are presented below. The question we examined should not be construed to imply that EPA or the states depend solely upon ambient standards to control groundwater contamination. In fact, EPA and the states have provisions for other reg- ulatory mechanisms, such as source controls, to manage contamination of groundwater resources. These programs are aimed at limiting migra- tion of contamination from specific pollution sources into the environ- ment. However, because of the inherent nature of standards as limiting values and the imperfect protection afforded by source controls, there is a potential for allowing degradation to occur to the standards' levels under an approach employing ambient standards and source controls. EPA has issued, or anticipates issuing in the near future, drinking water standards for 54 substances (see table IV.l).~ As noted, the U.S. Geologi- cal Survey's water data base (WATSTORE) contains data on 43 of those substances at wells throughout the United States.= A map of the United States, with a total area of more than 3.6 million square miles, can be thought of as a grid of square-mile cells. Wells contained in that have measurements for one or more of these substances exist in 12,072 of those cells (see figure IV.I). We analyzed the usgs data by creating a separate data set of the most recent measurement of each substance in each cell. We then wrote com- puter programs to compare each measurement for each of the 42 sub- stances against three values: its MCL, its MCLG, and the level associated with a one-in-one-million risk of cancer (for those 13 substances that UPA has identified as causing cancer). Our findings are reported as the per- centage of cells meeting the applicable guideline values for all sub- stances measured. Page 28 GAO~ PEMD-89-1 Groundwater Protection Appendix IV Potent~tl Degradation of Groundwater Table IV.l: EPA Drinking Water Standards Set and Anticipated' Current Anticipated One-in-one- Substance Current MCL Anticipated MCL MCLG MCLG million cancer risk Inorganicg Arsenicb 50.0 30.00 0 0.0022 Asbestos 7.00¢ LOc Barium~ 1,000.0 4,700.00 4,700.0 Cadmium~ 10.0 5.00 5.0 Chromium~' 50.0 120.00 120 0 Copper~ 1,300.00 1,300.0 Fluoride~' 4,000.0 4,000 Leadb~ 50.0 Mercury~: 2.0 4.00 4.0 Nitrate~ 10,000.0 10,000.00 10,000.0 Selenium~ 10.0 45.00 45.0 Silver~'~ 50.0 Pesticidas Alachlorr' 2.00 0 0.5000 Aldicarb~' 9.00 9.0 Atrazine~ 3.00 3.0 Carbofuran~ 40.00 40.0 Chlordaneb 2.00 0 0.0270 Dibromochloropropane 0.20 0 0.0250 2,4-D~ 100.0 70.00 70.0 1,2-dichloroproprane~ 5.00 0 0.5200 Endrin~'" 0.2 Ethylene dibromide 0.05 0 0.0004 Heptachlor~ 0.40 0 0.0760 Heptachlor epoxide~ 0.20 0 0.0380 Lindane~ 4.0 0.20 0.2 0.0260 ,, Methoxychlor~ 100.0 300.00 300.0 PentachlorophenoF 200.00 200.0 : Toxaphene~ 5.0 5.00 0 0.0300 2,4,5-TP~ 10.0 50.00 50.0 (continued) Page 29 GAO/PEMI)~9~I Groundwater Protection Appendix Poten~al D~gradation o1' Gro~mdwa~er Subatance Currem CurTant MCL Anticipated MCL MCLG Ona-in-one- million cancer risk Other organics Ac~lamide 0 0.0100 Benzeneb 5.0 0 1.3000 Carbon tetrachloride~ 5 0 0 0.2700 Ortho-dichlorobenzene~ 600.00 60O 0 Para-dichlorobenzene~ 75.0 75 1,2-dichloroethane~ 5.0 0 0.3800 1,1-dichloroethylene~ 7.0 7 Cis-1,2-dichloroethylene 70.00 70.0 Trans-1,2-dichloroethylene 70.00 70.0 Epichlorohydrin 2 O0 0 3.5400 Ethylbenzene~ 700.00 700.0 Monochlorobenzene~ 300.00 300.0 PCBsu 0.70 0 0.0050 Styreneb 100.00 100.0 2,000.00 1,1,1-trichloroethane~ 200.0 200 Trichloroethylene~ 5.0 0 Vinyl chlorideL 2.0 0 2.6000 0.0150 Xylene~ 12,000.00 12,000.0 Radlonucllde$ and othera Alpha particle 15 pCi/I Coliform bacteriab 1/100 mi Beta particle 4 mrem/yr Radium 226 and 228 5 pCi/I Total trihalomethanes 100 Turbidity 1-5 TU ~Standards are expressed in micrograms per I~ter except where noted ~ThlS substance formed part of our analys~s of groundwater quality CStandard expressed in m41~ons of fibers of at least 10 micrometers ~n length per liter ~EPA nas not issued an MCLG for this substance Page 30 Appendix IV Potential Degradation of Groundwater Figure IV.l: Distribution of Wells Used in This Study Page 31 GAO/P~9-1 Groundwater Protection The number of ceils differs among the three analyses because of restric- tions placed on the data by the collecting agency. That is, some data have a "remark code" associated with them. One type of remark signi- fies that the actual concentration may have been lower than the value that was stored (that we used in our analyses). When this was the case and the stored value was higher than the guideline against which it was being compared, we excluded that particular observation from our anal- ysis. As a result, at different guideline levels (MCL, MCLG, and one-in-one- million cancer risk), different numbers of cells count as measuring one or more contaminants. Our findings about how groundwater compares to drinking water stan- dards are qualified by the nonrandom distribution of cells with sites sampled. Although we cannot generalize from our sample of cells (12,072) to the universe of all possible cells (3.6 million), we base our conclusions on a large and varied sample. According to officials at the Geological Survey, much of the data contained in the WATSTOR~. data base were collected in response to perceived pollution problems. Therefore, the contaminant levels in the USGS wells will tend to be high and our f'mdings will very likely underestimate the percentage of groundwater that could be degraded in the nation as a whole if pollution levels were allowed to increase to the level of the drinking water standards. Findings Maximum Contaminant Levels We found that about 91.8 percent of ceils with stations do not exceed EPA maximum contaminant levels for any contaminant measured. (Not all contaminants are measured at every station.)~ As shown in table IV.2, in 988 cells (8.2 percent) at least one MCL was exceeded. Of these, a single MCL was exceeded in 861 cells (7.1 percent), two were exceeded in 92 cells (0.8 percent), and between three and eight were exceeded in 35 cells (0.3 percent). 3Approxin~ately 41 percent of the 12,072 cells with measurements are in South Dakota and Illinois. To determine the extent to which these two states affect the overall national totals, we also con ducted an analysis that excluded them. We found that excluding these two states from the analysis changed the result from 92 to 89 pereenc Page 32 GAO,'PEM~89~! Groundwater Protection Appendix IV Potential Degradation of Grotmdwater Table IV,2: Cells Exceeding Maximum Contaminant Levels Number of substances Number of guidelines exceeded Total measured 0 1 2 3 4 5 6 8 cells 1 3,091 221 0 0 0 0 0 0 3,312 2 725 66 3 0 0 0 0 0 794 3 236 17 0 0 0 0 0 0 253 4 89 17 0 0 0 0 0 0 106 5 216 21 4 0 0 0 0 0 241 6 2,679 77 9 3 0 0 0 0 2,768 7 223 28 6 1 3 1 0 0 262 8 291 17 12 1 0 0 0 0 321 9 366 57 9 2 3 1 0 0 438 10 738 62 4 0 0 0 0 0 804 11 262 19 4 0 0 1 0 0 286 12 73 16 3 1 0 0 0 0 93 13 106 13 3 0 0 0 0 0 122 14 152 12 1 0 1 1 1 0 168 15 133 15 1 0 0 0 0 0 149 16 57 6 1 0 0 0 0 0 64 17 65 9 3 1 0 0 0 0 78 18 61 5 1 0 0 0 0 0 67 19 789 85 5 1 0 0 0 0 880 20 171 14 1 0 2 0 0 0 188 21 27 14 2 0 0 0 0 0 43 22 31 3 2 0 0 0 0 0 36 23 90 9 1 0 0 0 0 0 100 24 22 2 2 1 0 0 0 0 27 25 22 I 0 0 0 0 0 0 23 26 24 6 1 0 0 0 0 0 3~ 27 46 8 1 1 0 0 0 0 56 28 55 5 0 0 0 0 0 0 60 29 68 6 9 0 0 0 0 0 83 30 114 14 0 6 0 0 0 0 134 31 16 4 2 0 0 0 0 1 23 32 6 0 0 0 1 0 0 0 7 33 22 6 0 0 0 0 0 0 28 3~ 6 2 0 1 0 0 0 0 9 35 8 3 1 0 0 0 0 0 12 36 3 0 1 0 0 0 0 0 4 37 1 1 0 0 0 0 0 0 2 Total 11,084 861 92 19 10 4 I I 12,072 Page 33 GAO/PEMI~8~! Groundwater Protection MCLS for inorganic compounds were exceeded in 850 cells, MCLS for pesti- cides were exceeded in 22 ceils, and MCLS for nonpesticidal organic com- pounds were exceeded in 135 cells. Six of 15 pesticides measured never exceeded the MCL level, while six others exceeded MCL levels in only one or two cells (see table IV.3). Table IV.3: Cells With One or More Sites Exceeding MCLs and MCLGs Total MCLs MCLGs Subetance cells' Number Percent Number Percent Inor~anlcs and others Arsenic" 5,980 143 2.4 2,720 99 3 Coliform bacteria 1,606 235 14 6 235 14 6 Barium 5,1 tO 17 0 3 17 0 3 Cadmium 3,232 162 5.0 162 5 0 Chromium 5,889 42 0.7 42 0 7 Copper 6,076 12 0 2 12 0.2 Fluoride 1,588 5 0 3 5 0 3 Lead 3,494 152 4.4 152 4 4 Mercury 3,343 14 0.4 ~ 4 0 4 Nitrate 3,838 156 4 1 156 4 1 Selenium 5,439 29 0 5 29 0 ~ Silver 4,980 7 One or more 10,266 850 Pesticides 0.1 / 01 8.3 3,206 31.3 Alachlor" 414 2 0.6 Aldicarb 4 0 Atrazine 942 4 o 0 0 o.~, 4 og Carbofuran 41 0 0 0 0 Chlordane° 1,243 2 0.2 21 5.3 2,4-D 1,220 0 1,2-dichloropropaneb 1,533 3 Enddn 1 r494 0 Heptachlorb 1,358 Heptachlor epoxideb 1,360 o o 0 0.2 32 82 1 0 0 0 Lindane 1,489 Methoxychlor 1,147 Pentachlorophenol 298 Texaphene" 1,311 2,4,5-TP 1,486 One or more 2,930 1 0.1 16 46 1 0 ~ :5 4.4 2 01 2 O1 0 0 0 u 1 0.3 I 0.3 9 06 11 2.6 0 0 0 0 22 0 8 83 39 fcontinued/ Page 34 GAO, p~AVID-89-1 Groundwater Protection Appendix IV Potential Degradation of Groundwater Total MCLs MCLGs Substance cells' Number Percent Number Percent Nonpestlcidal organics Benzeneb 2,651 34 1.3 97 95.1 Carbon tetrachloddeb 2,588 6 0,2 26 78,8 Ortho-dichlorobenzene 887 0 0 0 Para-dichlorobenzene 826 0 0 0 0 1,2-dichloroethane" 2,558 13 0 5 70 92,1 1,1-dichloroethylene 2,450 5 0,2 5 0,2 Ethylbenzene 2,514 1 0 1 0 Monochlorobenzene 2,441 3 0.1 3 0.1 PCBs° 1,266 2 0.2 7 1.6 Styrene 460 0 0 0 0 Toluene 2,650 2 0.1 2 0.1 1,1, l-trichloroethane 2,600 7 0.3 7 0.3 Triohloroethyleneu 2,582 85 3.3 202 96.7 Vinyl chlorideu 565 16 2.8 26 76.5 Xylene 307 0 0 0 0 One or more 3,335 135 4 0 307 9.9 aThe number of cells with one or more sites at which the substance was measured. Due to restrictions placed on the data, the actual number ot ceils that were ~r~cluded ~n our analysis may be different This effect ~s particularly significant in our analysis of MCLGs for those substances that have, or are antics- pared to have, an MCLG of zero. bFor these substances, the actual (or ani~c~pated) MCLG ~$ (or ~t ~s anticipated will be set) equal to zero For all other substances the MCLG is (or ~t is anhcipated will be set) equal to the MCL. One or more MCLS currently in force are exceeded in 926 cells. This com- pares with 988 cells in which one or more MCLS would be exceeded once ErA completes the next phase of its drinking water standards rule-mak- ing. This rough equivalence, in spite of the presence of 17 additional substances (for which monitoring data were available), is due to the fact that very few cells exceed anticipated MCLS for any of the substances that EPA is newly regulating (see table IV.4). Page 35 GAO/PEMI)-89-1 Groundwater Prowction AppendLx Potential Degradation of Groundwater Table IV.4: Cells With One or More Sites I Exceeding MCLs for Current and Anticipated Standards Substance Exceeds Cun*ent Exceeds Anticipated MCLs MCLs Number Percent Number Percent Inorganics and others Arsenic 5,980 74 Coliform bacteria 1,606 235 Barium 5,110 63 Cadmium 3,232 66 Chromium 5,889 80 Copper 6,076 Fluoede 1,588 5 12 ~43 24 146 1 2 1~ 20 ~6~ 1 4 42 0 TM i2 o ~ 03 Lead 3,494 Mercury 3,343 Nitrate 3,838 Selenium 5,439 Silver 4,980 Pesticides Alachlor 414 AIdicarb 4 Atrazine 942 Carbofuran 41 Chlordane 1,243 2,4-D 1,220 1,2-dichloropropane 1,533 Endnn 1,494 Heptachlor 1,358 Heptachlor epoxide 1,360 Lindane 1,489 Methoxychlor ~,147 Pentachlorophenol 298 Toxaphene 1,311 2,4,5-TP 1,486 152 4 4 18 0.5 14 156 4 1 74 1 4 29 7 0.1 0.4 '2 0.5 0 0 4 o4 U 0 2 0.2 0 0 0 0 0 ~ 01 ' 01 o 0 2 0i 0 U 0 1 03 9 0.6 9 0 6 0 0 0 0 (contlnuedl Page 36 GAO.,'PEMD-89-! Groundwater ?rotectio. Appendix IV Potential Degradation of Groundwater Exceeds Current Exceeds Anticipated Total MCLs MCLs Substance cells' Number Percent Number Percent Nonpestlcidal organics Benzene 2,651 34 1.3 Carbon tetrachloride 2,566 6 0,2 Ortho-dichlorobenzene 887 0 0 Para-dichlorobenzene 826 0 0 1,2-dichloroethane 2,558 13 0.5 1,1-dichloroeth¥1ene 2,480 5 02 Ethylbenzene 2,514 1 0 Monochlorobenzene 2,4,41 3 0.1 PCBs 1,266 2 0.2 Styrene 460 0 0 Toluene 2,650 2 0.1 1,1,1-trichloroethane 2,600 7 0.3 Trichloroethylene 2,582 85 3.3 Vinyl chloride 565 16 2.8 Xylene 307 0 0 aThe number of cells w~th one or more sites at wisch the substance was measured Due to restnctions placed on Ihe data, the actual number of cells that were included ~n our analysis may be different. Maximum Contaminant Level Goals In 71 percent of the cells, concentrations did not exceed the MCL6 for any substance measured.4 The measured concentration of most pesticides usually met even the MCLG. Six of the 15 pesticides measured are antici- pated to have MCLGs of zero. Eighty-three cells (3.9 percent of those cells with readings for at least one pesticide) exceeded an MCLa for one or more of the 15 pesticides (see table IV.4). One-In-One-Million Cancer Risk In 42.5 percent of the 5,114 cells in which an analysis of the measure- ment was possible, the contamination level was less than that associated with a one-in-one-million cancer risk for all of the 13 cancer-causing sub- stances. This compares to 96.4 percent of 7,973 cells that met MCLS and 9.1 percent of 3,323 cells that met MCLOS for one or more of the 13 substances. 4An MCLG could not be assigned for 3 of the 42 substances, and in these cases we employed the MCL. Restricting oUr analysis to the 39 would change the findings from 71.0 to 71.3 percent. For 13 of the 42 substances, the MCLG is (or it is anticipated by EPA that it wiU be) set equal to zero, For ail other substances, the MCLG is (or it/s anticipated will be) set equal to the MCL. Arsenic is one of the substances that, based on information from EPA, we assigned an MCLG of zero. It also was measured in nearly half the cells. As a result, arsenic by itself accounted for 70 percent of the 3,500 cells that exceeded an MCLG. Page 37 GAO/PEblD-89-1 Groundwater Protection Summary and Conclusions Approximately 71 percent of the groundwater in our study met all MCL~S measured and approximately 92 percent met all MCLS measured. This means that if states use Mc~s or MCU:S as "contamination ceilings," the quality of the vast majority of the groundwater we exarained could degrade. The fact that the W^TS~ORr data base probably over-samples areas with pollution problems suggests that for the nation as a whole the potential impact of adopting these drinking water standards as groundwater standards could be even greater than is indicated by our findings. Page 38 GAO/PEM]XS~I Groundwater ProtecUon Appendix V Comparison of Guidelines for Groundwater Uses Our fourth evaluation question was: "How do drinking water standards compare to guidelines for protecting uses of groundwater other than for drinking?" Our findings are presented below. Background Groundwater is widely used to irrigate crops and for livestock watering. Forty percent of crops and over 50 percent of livestock production rely on groundwater. Groundwater aquifers are also closely connected to riv- ers and lakes. EPA has estimated that groundwater is the source of approximately 30 percent of the nation's surface water. Findings The National Academy of Sciences has published recommended accepta- ble levels of contamination to protect irrigated crops for eight of the 54 substances and to protect livestock for 10 of the 54 (see table V.1). All of these are are metals and other inorganic compounds. In all cases, EPA maximum contaminant levels are at least as stringent as the guidelines established by NAS. EPA has issued guidelines to protect aquatic life for 27 of the 54 drinking water contaminants under authority contained in section 304 of the Clean Water Act. The National Academy of Sciences has published rec- ommended guidelines for two others (lindane and 2,4,5-TP). Fifteen of the 27 aquatic life guidelines issued by EPA are more stringent than their maximum contaminant levels for drinking water as are the two addi- tional guidelines published by NAS (see alSO table V. 1). The concentration of groundwater contaminants exceeds the more strin- gent of the aquatic hfe guidelines and MCLS in 33.1 percent of the one- square-mile cells in which uSgS measured groundwater contamination. When actual groundwater contamination is compared only to MCLS (see table IV.2 on p. 33), just 8.2 percent of the cells show excessive concentrations. Page 39 GAO/PEMD4L~I Grom~dwater Pro~ection Appendix V Compartzon of Guidelines for Groundwater Uses Table V.I: Comdafisen of Standards for Various Uses of Groundwatar~ Drinking Substance water MCLb Aquatic life Livestock Irrigation Inorganlcs Arsenic 3000 190.0000 200 100 Asbestos 7.00c Barium 4,700.00 Cadmium 5.00 0.6600~ 50 10 Chromium 120.00 11.0000~ 1,000 100 Copper 1,300.00 6.5000u 50~ 200 Fluoride 4,000.00 2,000 1,000 Lead 50.00 1.3000u t 00 5,000 Mercury 4.00 0.0120~ 10 10,000.00 100,000 Nitrate Selenium 45.00 Silver 50.00 Pseticidea Alachlor 2 00 Aidicarb 900 Atrazine 3.00 Carbofuran 40.00 Chlordane 2.00 Dibromochloropropane 0.20 2,4-D 35.0000" 50 ~0 1.2000~ 0.0043a 1,2-dichloroproprane 70.00 365.0000 Endrin 5.00 5,700.0000 0.20 0 0023a Ethylene dibromide 0.05 0.40 0.0038d Heptachlor Heptachlor epoxide 0.20 Lindane 0.20 0.0100~ Methoxychlor 300.00 0.0300~ Pentachlorophenol 200.00 3.5000d toxaphene 5.00 0.0002d 2,4,5-TP 50 00 2 0000° (continued) Page 40 GAO/PEMD-89-1 Groundwater Protection Appendix V Comparison of Guidelines for Groundwater Uses Drinking Substance water MCL" Aquatic life Livestock Irrigation Other organics Acrylamide 0.60 Benzene 5.00 5,300.0000 Carbon tetrachloride 5.00 35,200.0000 Ortho-dichlorobenzene 600.00 763.0000 Para-dichlorobenzene 75.00 763.0000 1,2-dichloroethane 5.00 20,000.0000 1,1 -dichloroethylene 7.00 Cis-1,2-dichloroethylene 70.00 Trans,1,2-dichloroethylene 70.00 Epichlorohydrin 2.00 Ethylbenzene 700.00 32,000.0000 Monochlorobenzene 300.00 50.0000d PCBs 0 70 0.0140d Styrene 100.00 Toluene 2,000.00 17,500.0000 1,1,1-trichloroethane 200.00 9,400.0000 Tdchloroethylene 5.00 45,000.0000 Vinyl chloride 2.00 Xylene 12,000.00 R-dionuclides and others Alpha particle 15 pCi/I Coliform bacteria 1/100 mi Beta particle 4 mrem/yr Radium 226 and 228 5 pCi/I 5 pCi/1 5 pCi/1 Total trihalomethanes 100 Turbidity 1-5 TU aStandards are expressed ~n m¢crograms per liter except where noted UThe MCL standards shown are a combination of current and anticipated standards The anticipated standard ~s used if the two differ CStandard expressed ~n millions of hbers of at least 10 m~crometers ~n length per I~ter. dMore stringent than the MCL. Page 41 GAO/PEMD-8~I Groundwater Protection Appendix V Comparison of Guidelines ~or Groundwater Uses Summary and Conclusions EPA maxilIll)_rfl contaminant levels would protect livestock watering and crop irrigation with an ample margin of safety. However, we found that for several substances, MCLS may be too high to protect aquatic life. A decision to apply maximum contaminant levels as groundwater stan- dards without allowing for greater stringency when local conditions warrant it (such as in areas of high groundwater recharge with low sur- face water dilution and ecosystems sensitive to these substances) could jeopardize sensitive species of aquatic life. Page 42 GAO/PEMI)-89-1 Groundwater Protection Appendix VI Questionnaire Organic O~onds 1. [ 0.075 state ~ to ~elo~ st~d~rd8 the eight volatile organic recently regulated by t~e ~ as 2. 3. 4. 6. Page 43 GAO,/PEMI~Sg-1 Groundwater Protection Questionmdre "~a~a--d ich~orobenzene : : : : Page 44 Appendix VI qaesttommlre ~lch of ~Ae ~llowirg ~eo~ des~i~es ~%e reas~A($) ~ s~e~e ~ ~.Ae ~ driflkir~ wateF st~ard~ as ~che ~y.J 1. ( 2. [ ] ~f~rcin~ th~ ~ is consMered 3.( ] tAe M~ is deemed a~equate EPA for drinki~ water p~ses the~ it is also acceptable for o~Aer uses of grouter 4. [ ] o~tmr (please specify): ~ich of t~e f~llowir~ best ~escrlb~ EPA ~ as tl~ basis f~r ~ ~C 9round~a~r ~]ulati~? [~k all 2. [ ] Tile ~ is p~rceive~ ~ beir~ mo~e strir~eflt tha~ the MOL 3. [ ] o~her (~ease ~pael~}= VOC sta~a~s ~n ~uidelifles ~ ~? Page 45 GAO/PEMD4L~I Groundwater Protection Appendix VI Questionnaire ¶ 1. Federal drinkin~ water standards ¶ may not protect non-~ri~kin~- ¶ ~r re~r~s ~ ~r state. ~ ~il~y. ¶ Page 46 GAO~ PEMI~89-1 Groundwater Protection Appendix VI Questionnaire 10. Consider basin~ 9t~undmmter standards for different locations c~ t~w the gz~ter is used in that ~ea. In y~ur opinion, ~ow ~ould the st~arda 2. [ I Cram~ter ~c~dards than drinkt~r~-water-ba~d o~hers ~ m~uld be as P~ IX: (~si~ ~o~mter Standards In t~is secti~ ~ ~ould lika you tD [~ov~e info~matic~ ce how ~ state uses Page 47 GAO/PEMI~8~I Groundwater Proteclion Questionnaire Page 48 GAO,, PEMD-89-I Groundwater Protection Appendix VI ~uestionnalre Cmt/nu~ if l~u c~k~d thet ~zm~d~t~ [~o~ticn ~s me* umd in deatsicn mkin~ cm~nin~ ~/of h~ m~/~ctlvitl~ list~ cn th* 12. Fow rare the 9~o~r~h~er i~ot~ction standards applied? (Chsck the ~ ~.?~ tmtim o~ 9ems~at~ strands.) 1. [ ! ~dels in c~der to determine i~pacts o~ alternativea 2.[ in less f~t~al or less 3.[ l~rt ot mnitorin~ r~u'lr~nts 4. [ ] At different times all of the above. ~0~tineao 5. [ ] Other 13. O~nsider the situatio~ Oco~d~at~r standards ~re ~l~, ~ ~t ~t, if at ~1, did ~ I~1 at ~lch ~ski~ ~ut ~ n~ic~ ~.) {~k ~.~ 5. [ ] ~ a ~y gr~t ~t. 14. Please list the areas/activities for ~hich ~he level of the standard ~d a 9rear imFact cn the final decision referrin9 t~ the list oa the l~evious Page 49 GAO/PEMI~89-1 Groundwater Protection Appendix VI Que~tionm~ e 16. Fow many investigations of violations of gro~dwater stardat~s have been ~tt-l~7 (Pill in the ~ of settled tmeatigations.) (Number of ~ettl~d investigations) 17. Of the settled cases, how many violations of gro~d~ter standards were fo~d? (Fill in ~he ~k~e~ of ~ttl~mmnts. ) (Number of violations) 18. In investigating potential violations, was a numerical groundwater standard 1. [ 1 Yes. 2. { ) No. 3. [ ] Sometimes, but not al~ays. 19. WMt sta~', flrding of violations of gt~m~mter standa~s? (~k al/ t~t 1. [ ] Shutting ~ the o~eratio~ Page 50 GAO/PEMD-89-1 Groundwater Protection Appendix VII Major Contributors to This Report Program Evaluation and Methodology Division Michael J. Wargo, Associate Director (202-275-3092) Boris Kachura, Group Director Dan Engelberg, Project Manager Robert M. Copeland, Project Staff Benigna S. Carroll, Survey Analyst Liz Scullin, Writer-Editor Page 51 GAO/PEMI~8~I Groundwater Protection Glossary Aquifer A geological formation, group of formations, or part of a formation that contains sufficient saturated permeable material to yield significant quantities of water to wells and springs. Carcinogen Any substance that produces cancer. Drinking Water Standard A limit on the allowable concentration of a substance in drinking water. (See maximum contaminant level and maximum contaminant level goal.) Groundwater Standard A limit on the allowable concentration of a substance in subsurface water. (See aquifer.) Maximum Contaminant A primary drinking water standard issued by Er^ under authority of the Level Safe Drinking Water Act. Maximum contaminant levels are set as close to MCLGS as feasible. Maximum Contaminant A nonenforceable health goal issued by Er^ under authority of the Safe Level Goal Drinking Water Act. ErA issues maximum contaminant level goals for substances for which the agency issues primary drinking water stan- dards. Mci. as are set at a level at which "no known or anticipated adverse effects on the health of persons occur and which allows an ade- quate margin of safety." Pesticide Any substance used to destroy or inhibit the action of plant or animal pests. Volatile Organic An organic compound that readily evaporates under normal conditions Compound of temperature and pressure. Many of the most commonly used indus- trial compounds are volatile organic compounds. Pa~e 52 GAO/PEMD~9-1 Groundwater Protection Related GAO Products Groundwater Quality: State Activities to Guard Against Contaminants (GAO/PrOD-SS-5, Feb. 2, 1988). Groundwater Standards: States Need More Information From EPA (GAO/ PF~MI~SS-6, Mar. 16, 1988). Groundwater: Control Programs and Research (GAO/PEMD-T-88-7, May 17, 1988). (973240) Page 53 GAO/pEMI)41~I GroundwaSer Protec~on