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~ Wisconsin Wisconsin is a major agricultural state that ranks near or at the top as a producer of several commodities including dairy products, green peas and sweet corn for processing, cranberr ies , and potatoes. Cash receipts for all agricultural commodities totaled nearly 35 billion in 1983, which ranked the state eighth in the nation in that category. Pr for to 1980, no incidents of groundwater con~=mina- tion caused by agricultural pesticides had been reported in the state. In 1980, after the discovery of aldicarb in groundwater in Suffolk County, New York, Union Carbide, working jointly with the EPA and several states including Wisconsin, collected samples to assess whether aldicarb residues were present in groundwater. By the on August 2 and 3, 1984, Holden visited with various individuals in Madison, Wisconsin, who are knowledgeable of groundwater problems in that state and of the recently enacted groundwater protection bill (1983 Wisconsin Act 410). The institutions represented by the individuals visited include the University of Wisconsin ~Madison; the Wisconsin Department of Agriculture, Trade, and Consumer Protection (DATCP), which licenses pesticide manufactur- ers who do business in the state and regulates pesticides to protect public health; the Wisconsin Department of Natural Resources (DNR), which is responsible for protecting and managing the waters of the state, including groundwater; the Wisconsin Water Resources Center (HIS WRC; jointly funded by the U.S. Department of the Interior and the state), which carries out or directs research related to water resources in Wisconsin; and the Wisconsin Public Intervenor's Office. 58
59 summer of 1981, analysis of samples taken jointly by Wisconsin and Union Carbide detected aldicarb in approxi- mately 18 percent of the wells sampled. That discovery, in conjunction with a growing national concern about groundwater contamination, resulted in additional sampling for a range of pesticides and ultimately contributed to the passage of the groundwater protection law, 1983 Wisconsin Act 410. Since 1957, irrigation in Wisconsin has burgeoned, and the demand on groundwater for irrigation is expected to rise dramatically in the next few decades. Several factors make large portions of the state ideal for irrigated agriculture. Relatively flat land can easily accommodate center pivot irrigation equipment. Sandy, permeable soils allow water to quickly infiltrate and drain, providing good soz1 aeration and root penetration. The sandy soils are easy to prepare for planting, need less plowing, and allow easier harvesting in wet weather. m ese conditions have allowed Wisconsin, once considered predominantly a dairy state, to become nationally prominent in the production of potatoes, peppers, snap beans, peas, corn, soybeans, and cranberries. Most of Wisconsin's 3,000+ high-capacity irrigation wells are located in the 10-county Central Sands area. The irrigation wells clustered in this region supply approximately 50-60 percent of the state's irrigated acreage. Although many of the soil and vadose zone characteristics of Wisconsin's Central Sands area are similar to those of Suffolk County, there is one important difference. Wisconsin's soils and groundwater are generally not as acidic as those of Long Island and on the average tend to be neutral or slightly acidic. The sand and gravel aquifer underlying the Central Sands region covers approximately 75 percent of the state. It is an unconfined aquifer that has no imper- meable layer overlying it. Consequently, it is highly susceptible to contaminants introduced at the soil - surface . TlIE STATUS OF EFFORTS TO MONITOR GRO~WA=R FOR RESIDUES OF AGRIC=~L PESTICIDES Past Monitoring Efforts Limited monitoring of groundwater for agricultural chemicals has occurred in Wisconsin. Historically, the
60 nether of samples collected and the range of pesticides subject to analysis have been small. One obvious reason for this is the relatively recent discovery of aldicarb in groundwater; time has been insufficient to develop a sampling protocol or to secure funding for a broad sampling program. Additionally, the DATCP laboratory and State Hygiene Laboratory have lacked the capacity to handle a large volume of samples. Consequently, until recently the state has had to rely on laboratory support from the EPA and Union Carbide. The data base on pesti- cides in groundwater in Wisconsin is therefore limited in time and space, although substantial (see Tables 3-1 and 3-3). More resampling has been done of wells in Wisconsin than elsewhere. Aldicarb As a result of sampling conducted after the discovery of aldicarb in the groundwater of Suffolk County, New York, Union Carbide detected aldicarb in Wisconsin's groundwater in 1980. Extensive well sampling for aldicarb began in the spring of 1981 and has continued quarterly in a cooperative program between the Wisconsin DNR and Union Carbide. In 1981, Union Carbide, the University of Wisconsin, the DNR, and the Portage County Community Human Services Department cooperated in an extensive well water sampling program for aldicarb. m e sampling concentrated on pot- able water wells in potato-growing areas thought to be most susceptible to groundwater contamination. Sites selected for sampling were those where nitrate contamina- tion was known;* aldicarb had been used during the pre- ceding 2 years; sandy, acidic soils with little organic matter predominated; a shallow water table existed; and irrigated agriculture was practiced. Based on these criteria, 363 well water samples were collected and analyzed from 10 counties. Of the samples, 51 (14 percent) contained aldicarb residues at or below the 10-pph state health guideline, 13 (4 percent) contained levels ranging from 11 to 30 ppb, and 4 ;1 percent) contained levels greater than 30 ppb. The highest concentration found was 111 ppb. *However , no correlation between nitrate contamination and pesticide residues in groundwater has been established.
61 The discovery of aldicarb in groundwater was a blow to Wisconsin potato growers, who consider aldicarb an extremely valuable pesticide. It is claimed to increase potato yields 15-25 percent over yields obtained by using alternative chemical controls for nematodes, Colorado potato beetles, aphids, and leafhoppers. Because various viral diseases of plants are associated with the occur- rence of certain insects or nematodes, control of these pests by aldicarb often results in disease suppression with corresponding yield increases and improvement in crop quality. Since the late 1970s, aldicarb has been the pesticide of choice for control of potato pests, particularly by the larger scale potato farmers. In 1981, prior to the label changes that restricted its use, Union Carbide distributed 866,000 lbs of Temik 1SG in Wisconsin. The zones of aldicarb contamination apparently occur primarily at locations where the soil and groundwater pH are slightly acidic. The pa in the Central Sands area differs widely due to the variable nature of geologic material deposited by glaciers. For example, areas where glacially deposited limestone or other alkaline geologic material is concentrated have soils and aquifer materials with a higher level of alkalinity than areas where more acidic material has accumulated. Consequently, the pE of the groundwater in the Central Sands region varies from 5.0 to 8.5. As mentioned before, pE is a critical variable in determining the persistence of aldicarb in groundwater, and studies by the WIS WRC show that aldicarb residues tend to be encountered more often where the soil and groundwater pE are low. Repeated sampling by the University of Wisconsin-- Mad~son staff in the Central Sands region has shown that groundwater contamination by aldicarb does not generally extend beyond 10 or 15 feet below the water table. Accordingly, the highest concentrations detected have been in shallow wells near the potato fields where aldicarb was used. The problem of contaminated domestic water supplies has been exacerbated by the common use of well points that penetrate just the top few feet of the aquifer. As a consequence, if aldicarb has leached to the water table, these shallow wells are especially likely to tap contaminated water. After aldicarb was detected in approximately 18 percent of the samples from the 1981 sampling program, severe restrictions were placed on its use for the 1982 growing season. The restrictions were agreed on by Union
62 Carbide, the DA$CP, and the Pesticide Review Boar d (comprising the Secretar ies of DATCP, DNR, and the Department of Health and Social Services). The restrictions were incorporated into an emergency rule by the DATCP and were submitted by Onion Carbide, in the form of label changes, to the EPA. In March 1982 the EPA approved these changes, which are summarized below: · Aldicarb is designated as a restricted use pesti- cide that may not be applied except by state-certif~ed private or commercial pesticide applicators, or by other persons under the direct supervision of a certified applicator. · Aldicarb applications on potatoes can only be made 4 to 6 weeks after planting, rather than at the time of planting. · Aldicarb cannot be applied to the same field more than once every 2 years. · Application rates for potatoes are reduced to a maximum of 2 lbs active ingredient per acre (ai/A) from 3 lbs ai/A. As a result of the reduction in the amount of aldicarb active ingredient that could be applied to Wisconsin potatoes, Onion Carbide removed nematode control claims from Temik labeling. · The revised label must include a statement of the potential for groundwater contamination associated with aldicarb use. Union Carbide estimated that these changes would reduce the potential for aldicarb leaching to groundwater in Wisconsin. The projected influence of those changes on reducing the probability of groundwater contamination is discussed in the comments on irrigation in the section CRITICAL PROBLEMS AND NEEDS. The restrictions on aldicarb use were included in a rulemaking change, first as an emergency rule for the 1982 growing season and then as a permanent rule prior to the 1983 growing season, under the authority vested in the Wisconsin DATCP. The purpose of the aldicarb rule is to minimize the quantity of total Aldicarb reaching groundwater and to prevent aldicarb levels in groundwater from exceeding 10 p p , the level the state has set as its advisory. In addition to the label rests ictions, the rule requires prospective aldicarb users to file a report of intended use with the DATCP at least 30 days before the date of use. Significantly, the rule further restricts the use of
63 aldicarb in areas where aldicarb concentrations in groundwater have exceeded 10 ppb. The rule states that aldicarb applications are prohibited if the intended application site is "located within a township quarter- quarter section of land lying wholly or in part within one mile of a sample point at which aldicarb residues have been detected in groundwater at a level exceeding 10 parts per billion" (Figure 3-1). The areas where aldicarb use has been restricted are referred to as moratorium areas. In 1984, 45 wells located in 22 different quarter-quarter sections were found to exceed the 10-ppb level for aldicarb. In 1985, 30 wells located in 25 different quarter-quarter sections were found to exceed the limit for aldicarb. These detections created 11 moratorium areas for the 1985 growing season encom- passing approximately 36,500 acres. Most of the mora- torium areas are located in Portage County. Delineation of a moratorium area is based on a completed groundwater analysis received by the DATCP no earlier than March 1 of the year immediately preceding the year of intended application. In certain cases, sites within the moratorium areas can be exempted from the prohibition-- for example, if the DATCP determines that the intended application site is not in the same recharge areas as the sample point with aldicarb concentrations exceeding the health standard. Samples used as the basis for establishing a mora- torium area must be collected by or under the supervision of the DNR, the Department of Bealth and Social Services (DESS), or the DATCP. Samples must come from a potable water supply well or any other well, provided the well construction and sampling methodology do not interfere with the integrity of the groundwater sample. Samples cannot be taken from high-capacity irrigation wells or any well located within 300 feet of such a well, which can bias water quality samples by influencing the hydraulic gradient of the aquifer in its vicinity. Under this rule, pesticide distributors and retail dealers are required to keep records of aldicarb sales and to file weekly sales reports with the DATCP. Green- house applications of aldicarb are exempt from the rule's · provlslons . The aldicarb rule can be amended at any tome if evidence indicates that the restrictions imposed on aldicarb do not satisfactorily protect groundw~ter. In fact, the DATCP is currently considering changes in the rule as a result of agency field research.
64 Town of Pine Grove T21N - RUE `~> Town of Almond TIN - ROE "A ' ~ '''X' ,. ~ L =4J:~ in . ~ ~ , <' I ~ ~0 Marks the 1-mile area from the ~i . ;¢ AS in.. __ ~ ~ `. renter of she more am area ' gas' ' ~''l'/: W~~ ~ ) 6~. - . 4~ ! J' ~ Designates the number assigned ) \: ! ; >_ ~ ~~ to the mom orium ama _g,] ,~,0,,o, ~ ~w('';"j jIN(\ 4Nw; ~ Hi,,,.: t..s /1 Ad_ A/ _t ~ . _ ~et' ci ti" ~ , I ED, 'A ,' ,,~,AV~U8- _ / ~~{~~ wall 1 ., - _ .. . j R8E,|^E ~ Moratorium area bo ndary<~' Portion of towns shown correspond to shaded area , _ _ _ , 6 5 ~ in . a qloj.ll`2 ~ ~ ,'7 ~s''6ltsil4~3 ~ ~ _~2l122~23 _ 25 30 29 ~1 2712G 25 3~ At _~'35 ~ ~~Al~on~ Portage FIGURE 3-1 Example of moratorium area in Portage County. SOURCE: Wisconsin Department of Agriculture, Trade, and Consumer Protection. Reproduced from a topographical map, courtesy of U.S. Geologica1 Survey.
65 me most recent Union Carbide summary of groundwater analyses for aldicarb in Wisconsin is shown in Table 3-1. These data indicate that as of January 1985, 963 wells in 22 Wisconsin counties have been sampled collectively 2,293 times. Aldicarb has been detected at 116 sites tl2 percent). Currently, 36 sites (4 percent) have aldicarb concentrations greater than 10 ppb. According to a Union Carbide summery accompanying the data, of the 190 wells that have been resampled 2 or more times, 123 wells (65 percent) show a downward residue trend, with 87 of those having no remaining detectable residues. By comparison, 17 wells (9 percent) have shown increased aldicarb concentrations, and the remaining 50 wells (26 percent) have had no change. Union Carbide believes these data indicate that the overall trend in Wisconsin is toward lower residues, presumably because of declining use caused by the new label restrictions. In 1984 the highest concentration of aldicarb found in the water from a domestic well was S4 ppb--down from a high of 111 ppb in 198L. Sampling for Additional Pesticides The Wisconsin DNR has been actively sampling drinking- water wells and analyzing the samples for some of the 45 pesticides determined by the DATCP as having the greatest potential for reaching groundwater (Table 3-2). This list of priority pesticides was identified by the DATCP staff in collaboration with other Wisconsin agencies and with EPA staff in Washington, D.C., and Georgia. The f irst 22 chemicals on the list are Chose the DATCP identified as posing the greatest potential threat to groundwater. These should receive the highest priority in the DAN sampling program, which began in July 1983 and is continuing on a regular basis. Field sampling is carried out by DNR personnel from all six DNR district offices throughout the state, although the bulk of the sampling has occurred in the Central Sands region. Analytic support is provided by Union Carbide, which runs approximately 600 water samples (plus quality assurance samples) per year for DNR without charge, and the State Hygiene Laboratory. Annual state funding for the program has been approximately $100,000 with a total of 1,500 analyses allotted for pesticides each of the past 2 years.
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67 TABLE 3-2 Priority Pesticides Identified by the Department of Agriculture, Trade, and Consumer Protection (DATCP) Pesticide Remar ks 1. Alachlor ( Lasso) 2 . Metolachlor ( Dual) 3. Amitrole (Amizole) 4. Chloramben (Amiben) 5. Aldicarb (Temik) 6. Carbaryl (Sevin) 7. Carbofuran (Furadan) 8. Metam-sodium (Vapam) 9 . Methomyl ( Lannate, Nudr in ) 10. Oxamyl (Vydate) 11. Ethylenethiourea (ETU) (breakdown of dithiocarbamates) 12. MBC (breakdown of benon~rl and thiophanate ) 13. Dinoseb (Dinitro) 14. Dibromochloropropane (OBCP) 15 . K~B (Terrachlor ) 16. Dimetboate 17. Disulfoton (Disyston) 18. Fonofos (Dyfonate) 19 . Phorate (Thimet, Rampart ) 2 0 . Terbufos ( Counter ) 21. Picloram (Tordon, Amdon) 22. Linuron ( Lorox) 23 . Dicamba tBanvel) 24. Paraquat 25. EPTC (Eradicane, Eptam) 26. D~D (Vidden D) 27. Diazinon (spectracide) 2 8 . Isofenphos (Amaze) 29 . Methamidophos (Monitor ) 30. Methyl Parathion 31. 2,4-~ 32. Maleic hydrazide 3 3 . DCPA (Dacthal, chlorothal) 3 4 . B~dothall 3 5. Atrazine (Aatrex) }Iigh use, high leach, and detect ion High use, unknown acceptable daily intake (ADI ) Animal carcinogen Suspected animal carcinogen and leach High toxicity, leach, and high detection Suspected animal carcinogen and high use High detection, toxicity, use, and leach Unknown ADI, high leach, potential increased use Low detection, variety of use High toxicity, low use Animal carcinogen, leach, use Bigh use, leacb, unknown toxicity Bigh toxicity, detection, and use Animal carcinogen, high leach, detection in other states Animal carcinogen and leach Medium toxicity, var iety of uses, breakdown of concern Bigh toxicity and leach Bigh toxicity, leach, and use High toxicity, leach, and use Bigh toxicity, leach, and use Suspected animal carcinogen High use, low ADI Medium toxicity and use, high leach Low use but potential for increase Low toxicity Low use (sample selectively where use known) Variety of uses and high toxicity High toxicity, increasing use (because of efficacy problems, withdrawn from Wisconsin market) High toxicity, low leach Variety of use, high toxicity, low leach Signif icant use, large public concern Lack of information on ADI, low use Low detection and toxicity Medium toxicity, low use Bigh use, low detection and toxicity
68 TABLE 3-2 (Continued) Pesticide . 36. Cyanazine (Bladex) 37. Metribuzin (Sencor) 38. Simazine (Bitemal, Princep) 39. Bromacil (Byvar) 40. Chlorothalonil (Bravo) 41. Dichlobenil (Casoron) 42. Butylate (Susan') 43. Acephate (Orthene) 44. Chlorpyrifos (Lorsban) 45. MCPA (Agroxone) Remarks No ADI for teratogenicity reasons, lack of information Low detection, high use Medium use, low detection and toxicity Detection, leach, low toxicity and use Low toxicity and leach Low use and toxicity Bigh use, low leach and toxicity Significant use on some crops Low leach, medium toxicity Dow toxicity NOTE: Category 1 high priority chemicals are the first 22. SOURCE: HA Framework for Assessing Pesticide Impacts on Wisconsin Ground Water,. 1983, Final Report of the Ground water/Pesticide Surveillance Committee, prepared by the Wisconsin Ground Water/Pesti- cide Surveillance Subcommittee: Charles Goethel, DNR; O. R. Ehart, DATCP; and Bank Weiss, DHSS. Results of this DNa sampling program are given in Table 3-3. Pesticides have been detected in 9-10 percent of the samples, which are taken from wells in worst-case areas (that is, heavy pesticide use, shallow water table, highly permeable soils, and so on). Aldicarb has been the only frequently detected pesticide whose presence in groundwater can be attributed to normal field applica- tion. m e relatively high detection nephews for alachlor, metolachlor, and atrazine are associated with a point source problem discussed in the subsection Current SamDlina Efforts. _ ~ Is interviewed during this trip criticized various aspects of DNR'S sampling program. For example, it was generally suggested that sound quality control and quality assurance procedures were not always followed during some stages of the sampling and analysis program, perhaps partly because of pressure to conduct the sampling and a lack of staff training. For example, Harkin et al. (1984) noted in their WIS WRC report "Pesticides in Groundwater Beneath the Central Sand Plain of Wisconsin" that some detections of pesti- cides in initial screenings were false positives and were not supported by resampling and reanalysis by more sensitive analytic methods.
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70 Current Sampling Efforts The DNR's pesticide sampl ing program continues to assess Wisconsin's groundwater for the 45 pesticides determined by the DATCP to be most susceptible to leaching. Funding for the sampling program is expected to remain at a level of approximately Sloo,ooo per year, with a similar amount used to expand and improve the capabilities of the State Hygiene Laboratory. The DNE groundwater staff indicated that the emphasis of its sampling program for pesticides may be shifting away from nonpoint to point sources because of recent contamination discoveries at handling and storage facilities. To illustrate its concern, the staff cited a recent incident in Rusk, Wisconsin. Pesticides have been detected in 23 out of 27 (85 percent) domestic water wells in that small community. Apparently, the contamination results from spillage at a mixing and loading site of a commercial applicator's place of business and at a dealer warehouse. m e highest concentrations of pesticides detected in samples from those wells included alachlor (Lasso) at 88 ppb, atrazine at 140 ppb, and metolachlor (Dual) at 55 ppb. Approximately 40 percent of the wells had detection levels greater than the health standard established for at least one of the pesticides found. The citizens of Rusk are being advised not to use their well water, and alternative supplies are being provided by the warehouse owners. During an interview, an official of DATCP agreed with the ONE decision to begin investigating point sources (specifically handling and storage facilities) but at the same time believed that the sampling effort to charac- terize nonpoint sources had not yet generated enough reliable and useful data to ascertain the full scope of the problem. The official believes DNR may be over- relying on the low percentage of detections found to date from a less than rigorous sampling program and therefore too quickly concluding that groundwater contamination caused by normal field uses of pesticides is not a serious problem. Be stressed that only high-quality, reliable analytic data from samples collected in a rigorous sampling program can conclusively determine the extent and significance of pesticide/groundwater problems. The DNR staff continues to monitor aidicarb concentra- tions in groundwater and is collecting approximately 600 samples per year, which are being analyzed by Union
71 Carbide. m e sampling is done on a quarterly basis and is limited to water supply wells. Groundwater Protection Bill On May 4, 1984, Wisconsin Governor Anthony Earl signed into law a groundwater protection bill (1983 Wisconsin Act 410) designed to protect the quality of the state's groundwater. m e bill requires each regulatory agency to identify substances that either have already been detected in groundwater or are likely to reach ground- water as a result of activities the agency regulates. Groundwater protection standards for those substances ale then to be established on a two-tiered basis: ~enforce- ment standards n and "preventive action limits.. The enforcement standards are based on the most recent federal standard established by the EPA for the specific compound in question. When an enforcement standard is attained or exceeded, the appropriate regulatory agency must prohibit the activity from which the substance originated, unless it can be demonstrated that an alternative action will achieve compliance with the standard. Prohibitions can be limited to specific sites. The preventive action limits (PAL) are established at 10 percent, 20 percent, or SO percent of the enforcement standard depending on health-related characteristics of the particular substance. A PAL of 10 percent will be established for any substance having carcinogenic or teratogenic properties; a PAL of 20 percent will be established for substances having other public health concerns, such as acute toxicity; and a PAL of 50 percent will be established for public welfare concerns, such as taste or odor. m e PALs serve two purposes related to pesticides. First, a PAL would be used in considering management practices so that the potential for ground- water contamination is evaluated prior to a pesticide's use. Second, the PAL triggers remedial actions designed to prevent the level of that compound from reaching the enforcement standard, which would require a ban. Thus, if a pesticide is detected above a PAL, the DATCP would be empowered to impose regulations short of a ban. The act also stipulates that a statewide groundwater monitoring and sampling system be established to implement the overall groundwater management program. ffl e DNR, in cooperation with other state agencies and a newly established Ground Water Coordinating Council, is
72 to develop and manage the groundwater monitoring program. This coordinating council is an eight-member body established by 1983 Act 410 to advise state agencies in the coordination of nonregulatory programs relating to groundwater. Five classifications of monitoring activities are outlined under 1983 Act 410: 1. Problem assessment monitoring--.To determine and assess the extent to which substances are in the ground- water.. This statewide sampling program would evaluate problems caused by a wide range of pollutants including volatile organic compounds (VOCs), aldicarb, or other pesticides. 2. Regulatory monitoring--.To determine the extent to which the groundwater is contaminated and meets or exceeds numeric water standards, and to obtain informa- tion necessary for the implementation of site specific response.. This activity is equivalent to shot spot" monitoring. 3. At-risk monitoring--.Monitoring areas where substances identified by regulatory agencies are in groundwater or where preventive action limits or enforcement standards have been attained or exceeded.. m is activity focuses on the sampling of individual wells in general problem areas. 4. Management practice monitoring--.Applied research monitoring to determine the appropriate management practices necessary to meet design and management criteria and the adoption of regulatory responses for groundwater contamination.. This activity pertains to sampling in research projects on management practices and to sampling conducted by the DATCP to check effectiveness of label changes and other actions taken to minimize groundwater contamination. S. Monitoring plan--.Planning to coordinate and carry out the above monitoring components.. This activity includes the sharing and coordination of data. The bill has other provisions relating to agriculture and groundwater. It creates a new program within the DATCP to regulate the storage of bulk quantities of fertilizer and pesticides. Rules have recently been promulgated for this program. In addition, the bill provides for laboratory certification and registration procedures to be established by the DNR (a proposed rule has been issued). Furthermore, it creates a well
73 compensation fund that will pay up to 80 percent of the cost of repair or replacement of a contaminated residential well that serves less than five dwelling units; certain types of livestock wells also qualify for this fund. Also as a result of the groundwater law, the DATCP has written a rule outlining its regulatory program and the DNR has written a rule both outlining its regulatory program and establishing enforcement standards and PALs for several substances. The programs established by Act 410 will be financed by a combination of general-purpose revenues and a special fund created to support the groundwater-related activities of the DATCP, DNR, DOSS, and the Wisconsin Department of Industry, Labor, and Buman Relations. This special fund will be supported by fees on activities with the potential to impact groundwater. Revenue sources include annual license surcharges of 32,000 for primary pesticide manufacturers plus an annual S2,000 research fee paid to the DATCP, and an increase in annual license fees for formulators from SlOO to S200 for those formu- lators with a single pesticide and to 3400 for those manufacturing or labeling more than one compound. The revenues generated by these license increases and ear- marked for the groundwater activities of the state were approximately $300,000 in 1984. Additional revenue for groundwater activities are generated by a tax of So.10 per ton on fertilizer spread by applicators. This tax is in addition to a prior SO.lO levy for an industry- sponsored research fund, which the legislature authorized to be expended on groundwater research. Thus, half of the 30.20 tax on fertilizers will go directly to the special groundwater fund and half will support research focused on the influence of fertilizers on groundwater quality. me revenues generated by this tax were approximately 4130,000 in 1985. m e well compensation fund was established with S500,000 authorized from general revenue funds. An obvious difficulty in implementing 1983 ACt 410 is the lack of federal guidance for setting enforcement standards and PALs. In particular, the EPA has established few federal maximum contaminant levels (MCDs) for drinking water. On July 29, 1983, Tom Dawson, Wisconsin Public Intervenor, speaking before the U.S. Senate Subcommittee on Toxic Substances and Environmental Oversight of the Committee on Environment and PubliC Works, noted,
74 First and foremost, there is a tremendous need among the States, especially Wisconsin, for the adoption of reliable drinking water standards establishing .max~mum contaminant levels. against which to measure groundwater pollution. Although EPA is charged with setting these standards, including those for toxic substances, not nearly enough standards have been set. There is a need for Congress to ask why this is so, and to spur EPA into action. For chemicals without federally established MCLs, Wisconsin will have to consider suggested no adverse response levels (SNARLsJ, health advisory levels (PALS), health guidelines (HGs), or acceptable daily intake levels (ADIs) established at the federal level. Where no federal standards have been established, states like Wisconsin may have to create standards. Not only is this a resource-intensive problem, but it opens the possi- b~lity of inconsistent standards between states. Thus, many state officials like Dawson believe it is critical that the EPA establish many additional MCLs and health advisories for pesticides and other toxic chemicals. CRITICAL PROBLEMS AND NEEDS Educational Efforts by the Extension Service The University of Wisconsin Extension Service (UWEX) is developing extension programs and materials on ground- water in conjunction with the Wisconsin Geological and Natural History Survey, the DATCP, and the DNR. The extension materials are designed to educate farmers and the general public about the nature and occurrence of groundwater, groundwater flow , relationships between land use and well water quality, irrigation scheduling and its relationship to the movement of pesticides and ferti- lizers, and livestock waste management. A future UWEX goal is to develop extension recommendations for agricultural management strategies to reduce the potential for groundwater or surface water contamination from pesticides. However, before recommendations can be made, more applied research on this issue must be carried out. Field testing of various management strategies is especially needed.
75 In June 1984 UWEX and the New York Extension Service (NYEX) jointly submitted a proposal to the USDA Extension Service (ES) to develop a pilot groundwater education program and information transfer network. m e primary purpose of the program will be alto develop, test and refine materials that can effectively be used by community resource development, family living, agricul- ture, 4-H, and State, area, and county Cooperative Extension Service faculty to assist individuals and communities in identifying and dealing with probl--=c and concerns related to groundwater contamination.. A secondary purpose of the proposed program will be to Develop an information-sharing network to facilitate the exchange of educational material and programs developed through the pilot program, and by other states, so that Cooperative Extension Service nationally can effectively use research-based educational materials and programs to respond to individual and public groundwater educational needs in a tamely and effective manner. A significant thrust of this program will be the development of and documentation for computer models that can be used to illustrate the physical nature of ground- water movement and the potential for contamination of groundwater. The program will include a series of computer programs developed by Cornell University that relate land use and a range of environmental variables to groundwater quality. UWEX and NYEX have separately developed a number of groundwater-related educational materials, but major needs still exist. A proposed joint effort to develop extension publications on groundwater contamination risks and related topics is on hold because funding is not available. Irrigation University of Wisconsin researchers have been studying the influence of irrigation on pesticide movement. Field tests conducted in 1982 investigated the effectiveness of the label changes made in 1981 for aldicarb in Wisconsin. The findings suggest that aldicarb applica- tion at emergence (rather than at planting) is effective in reducing the leaching of a~dicarb without signifi- cantly diminishing insecticidal efficacy, crop residues, and yield. Leaching is reduced because an increase in
76 soil temperature of approximately 6°C between the time of planting and the tome of emergence favors a more rapid rate of degradation of aldicarb and because the aldicarb is not available during the time between planting and emergence when the plants are not transpiring and cool spring rains occur. In addition, later applications of aldicarb can result in better crop protection because the developed root system can more effectively capture the soil water containing the pesticide. A UWEX computer program has been developed to assist growers in irrigating more efficiently. This water budget program is called the Wisconsin Irrigation Scheduling Program (WISP), and it uses estimates of crop water use to monitor soil moisture conditions. WISP considers the available water in the root zone to be a r eservoir that the plant utilizes in transpiration. The amount of water that can be removed from this reservoir without stressing the crop is called the Allowable depletion,. and it varies with soil type and crop. WISP is designed to maintain soil moisture within 25-75 percent of the allowable depletion by balancing evapo- transpiration (ET) losses with gains from rainfall or irrigation. Input data required to run WISP include rainfall, irrigation, ET, and allowable depletion. For the pas t few years, growers in the Central Sands region have been able to calculate allowable depletion using a hand-held calculator version of WISP. Growers were required to maintain daily logs of precipitation that had fallen on crops and of the irrigation they had applied; they also had to calculate ET losses. In 1984, WISP was put on the UNEX main computer along wi'ch daily ET data and 24-hour and 48-hour rain probabilities. Using a grower 's irriga- tion and rainfall data, WISP can calculate the amount and percentage of allowable depletion and can project deple- tion over the next 24 or 48 hours if the crops receive no additional irrigation or rainfall. The computer version of WISP is available through the county extension offices; some individual growers have access to the UWEX computer system and can use the program directly. WISP has three important benefits: water conservation, energy conservation, and reduced leaching of pesticides and fertilizers out of the root zone .
77 Groundwater Resource Evaluation The Wisconsin Geological and Natural History Survey (GNBS), in conjunction with FLEX, the USGS, and the DNR, is conducting groundwater resource evaluations at the county level. This program, which focuses on groundwater as a resource, has important implications for the assess- ment of possible contamination by pesticides. Maps with a 1:100,000 scale identify areas of highest contamination potential, direction of groundwater movement, potential aquifer yields, and depth to the water table and bedrock The GNHS groundwater resource evaluation program is patterned after similar surveys that have been carried out for years by the Illinois Water Survey, a branch of that state's geologic survey. The evaluations are usually done in cooperation with the county under cost- sharing agreements that rely on the county paying from 10 to 50 percent of the cost depending on the specific funding sources available when the evaluation is initiated. m e cost to the county may range from S2,500 to S25,000 depending on the availability of information and the level of detail requested or needed. Some water quality information is generated from sampling conducted during the evaluation and includes such parameters as nitrates, chlorides, alkalinity, hardness, and bacteria. Analyses for organic chemicals have not been performed, however. Prevention of Groundwater Contamination . Wisconsin has identified the prevention of groundwater contamination as a critical issue. However, the expense associated with aquifer restoration is prohibitive in many cases, and much more work is needed to identify potential contaminants, sensitive hydrologic areas, and the various physical and chemical properties of soils that contribute to groundwater contamination. m e Director of the ITS WRC pointed out that a better understanding of the physical and chemical processes occurring in the vadose zone is crucial to the prevention of groundwater contamination. To detect pollutants before they enter the groundwater, more emphasis is being placed on research to characterize transport through this zone. Protocols need to be developed for the monitoring activities, an effort that will require multidisciplinary
78 research to integrate the various components of this complicated system. Vadose zone monitoring can afford an early warning of potential groundwater contamination. If a problem is detected, remedial measures can be implemented sooner, thereby reducing or eliminating associated aquifer restoration costs. The depth of the vadose zone in a specific area will directly influence the Plead tomes granted by such monitoring. For example, areas in the Southwest may have a vadose zone hundreds of feet thick compared to that of the Central Sands region of Wisconsin, where the unsaturated material is only 5 to 50 feet thick. AGRICULTURAL MANAGEMENT STRATEGIES AVAILABLE TO MITIGATE PESTICIDE/GROD~DWATER QUALITY PROBLEMS Potato Integrated Pest Management Program The potato is a major vegetable crop in Wisconsin, where 60,000 to 70,000 acres are planted annually. Total value of the crop exceeds S100 million. Unlike Suffolk County, New York, Wisconsin potato production is not plagued by the golden nematode. Nematodes generally do not pose serious problems except for early plant die-off, which is associated with them and with soil pathogens (fungi). However, the Colorado potato beetle, potato leafhopper, green peach aphid, tarnished plant bug, and variegated cutworm are economically important insect pests that require insecticides for control. In addition, fungi can cause severe early and late blight and require numerous applications of fungicide. The potato leafhopper is the single most Sopor ten t yield- reducing insect pest of potatoes in Wisconsin, but the Colorado potato beetle is increasingly significant. Populations of the latter were significantly reduced in the 1940s due to the widespread use of ODT, but during the last decade the numbers and range of distribution of the beetle have steadily increased, and its management is now a major concern of growers. m e Importance of pest problems and pesticide use in the Wisconsin potato industry led to the initiation in 1979 of an integrated pest management (IPM) program in two major production areas three Central Sands counties (Portage, Adams, and Waushara) and Langlade County (a certified seed production area). The program was
79 established to demonstrate the concepts of IPM to the potato industry and to illustrate how IPM could alter approaches to pest management practices so as to reduce environmental impacts associated with pesticide usage on potatoes . The UWEX staff assessed the effectiveness of the Wisconsin potato IPM program on the basis of grower acceptance of the program and adoption of IPM philosophy and techniques, alteration of pesticide use patterns, and economic feasibility. Overall, the acceptance by growers was considered good and increased each year, despite the addition in 1981 of a program charge on acreage scouted for pests to help defray costs. The total acreage scouted in the program increased from approximately 5,000 acres in 1981 to 8,000 acres in 1982. This program demonstrated that during two seasons of high disease pressure and moderate insect pressure, IPM was economically favorable. Growers using the IPM program saved 37.50 to $9.00 per acre for the season. Additional, but nonquantifiable, benefits to growers from participation in the program included the peace of mind generated by regular crop inspection and by a trained, unbiased second opinion on pest problems. The Wisconsin potato TPM program was turned over to the private sector for the 1983 growing season. Several private consultants offered scouting services patterned after the UWEX program. In the first year, the growers who used IPM applied fungicides more frequently and insecticides less frequently than growers who did not use IPM. In succeeding years, with improved IPM techniques, applications of both fungicides and insecticides decreased. In part because of IPH, aldicarb use on Wisconsin potatoes declined some 50 percent through 1985. Thus, IPM has helped to diminish the threat of ground- water contamination. Best Management Practices IPM focuses on managing pests by scouting; the development of additional best management practices specifically designed to mitigate groundwater contamination by agricultural chemicals is a critical need felt within the Wisconsin Extension Service. A member of the extension staff identified the calibration of spray equipment as an important best management practice. Growers need to be better informed
80 that nonuniform application of pesticides (or fertilizers) can occur if spray equipment is faulty or poorly calibrated. Before sending spray rigs into Me field, growers should conscientiously determine the proper size of nozzle tip, spray width per nozzle, flow rate from the nozzle, and consistency of flow rate from the nozzle.
