160.21 Adoption of rules for regulatory responses for groundwater contamination. (1) For each substance for which an enforcement standard or a preventive action limit is adopted by the department, each regulatory agency shall promulgate rules which set forth the range of responses which the regulatory agency may take or which it may require the person controlling a facility, activity or practice which is a source of the substance to take if: (a) The preventive action limit is attained or exceeded at the point of standards application; or (b) The enforcement standard is attained or exceeded at the point of standards application. (2) Each regulatory agency shall determine by rule the point of standards application for each facility, activity or practice which is the source of a substance for which an enforcement standard or a preventive action limit is established, as follows: (a) If monitoring is required under existing rules for a facility, activity or practice: 1. The regulatory agency shall establish a point of standards application at any location where groundwater is monitored for the purpose of determining whether the preventive action limit for a substance has been attained or exceeded. 2. The regulatory agency shall establish a point of standards application at the following locations for the purpose of determining compliance with enforcement standards, or determining whether design and management practice criteria established under s. 160.19 (2) (a) successfully maintain compliance with preventive action limits: a. Any point of present groundwater use; b. Any point beyond the property boundaries of the premises where the facility, activity or practice is located or undertaken; and c. Any point beyond the design management zone but within the property boundaries of the premises where the facility, activity or practice is located or undertaken. (b) If monitoring is not required under existing rules for a facility, activity or practice: 1. The regulatory agency shall establish a point of standards application at the following locations for the purposes of determining whether the preventive action limit or the enforcement standard is attained or exceeded: a. Any point of present groundwater use, except the regulatory agency may exempt points of nonpotable groundwater uses if the regulatory agency determines that the substance will not affect the nonpotable groundwater use; and b. Any point beyond the property boundary of the property where the facility, activity or practice is located or undertaken.
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2. The regulatory agency may establish by rule additional points of standards application which the regulatory agency determines are necessary to protect future groundwater uses and the public interest in the waters of the state. (c) If facilities are subject to regulation under chs. 283 or 289 to 292, the department shall develop by rule and utilize points of standards application for purposes of facility design, the review of facility performance and enforcement as follows: 1. Rules promulgated by the department under s. 289.05 (1) relating to facility design shall establish design criteria which ensure compliance with s. 160.19 (2) at any point of present groundwater use, at property boundaries and at any point beyond a 3-dimensional design management zone within property boundaries established under general criteria specified by rule and applied to individual facilities. 2. The department shall consider any point at which groundwater is monitored and at which a preventive action limit is exceeded a point of standards application for purposes of facility performance review, including investigations and evaluation of specific sites. If the point is within the design management zone, the department shall evaluate the location of the point, specific characteristics of the site, the nature of the substance involved and the likelihood of substance migration in assessing the need for response activities. 3. The department shall establish the point of standards application for enforcement standards at any point of present groundwater use, at property boundaries and at any point beyond a 3-dimensional design management zone within property boundaries established under general criteria specified by rule and applied to individual facilities. (d) The department shall establish criteria for design management zones by rule for the facilities specified under par. (c). The rule shall take into account different types of facility designs. The design management zone which is applied to a facility utilizing the criteria in the rule may be adjusted based on the following factors: 1. Soil type, depth and permeability; 2. Type, depth and permeability of bedrock; 3. Volume and characteristics of the waste involved; 4. Mobility of contaminants; 5. Distance to property boundaries and surface waters; 6. Present and anticipated future uses of land and groundwater; 7. Expected useful life of the facility; 8. Depth, direction and velocity of groundwater and other hydrogeologic factors; or 9. Likely methods for abatement if an enforcement standard is exceeded. (e) The department and each regulatory agency shall enter into a memorandum of understanding setting forth the criteria for acceptable monitoring wells and sample handling for the point of standards application. (3) Responses may include remedial actions, revisions of rules or criteria on facility design, location and management practices, prohibition of an activity or practice or closure of a facility. Remedial actions for a specific site may include, but are not limited to, investigations, relocation, prohibition of activities or practices which use or produce the substance, closure of a facility, revisions of operational procedures, monitoring or, if only a preventive action limit is attained or exceeded, no remedial action. Responses may vary depending on the type and age of the facility, the hydrogeological conditions of the site and the cost effectiveness of alternative responses that will achieve the same objectives under the conditions of the site. Responses shall take into
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account the background water quality at the site, the uses of the aquifer, the degree of risk, the validity of the data and the probability of whether, if a preventive action limit is exceeded, the enforcement standard will be exceeded at the point of standards application. In requiring a remedial action for a specific site, the regulatory agency shall use the authority and existing protections, including, but not limited to, due process provisions in other applicable statutes. (4) In setting forth the range of responses and providing for implementation of appropriate responses under the rules promulgated under subs. (1) and (3), the regulatory agency shall consider, where applicable, the following: (a) Risk-benefit considerations including, but not limited to: 1. Uses and substances alternative to the present use of the particular substance. 2. Risks and benefits of the alternative uses or substances. 3. Reliability and comprehensiveness of the information available for assessing such risks and benefits. (b) Hydrogeological considerations including, but not limited to: 1. The depth to groundwater. 2. The soil characteristics. 3. Groundwater gradients and flow direction. (c) Management and practice considerations including, but not limited to: 1. Reliability of sampling data. 2. The geographic extent of the substance if detected in groundwater and the size of the population affected. 3. The efficacy of label restrictions and other practical measures to minimize the concentration of the substance in the groundwater. 4. The existing effects and potential risks of the substance on potable water supplies. 5. The risks considered when the standard at issue was established or adopted. 6. The known depth of the substance in the groundwater. 7. Data and information provided by the manufacturer on the environmental fate of the substance. History: 1983 a. 410; 1995 a. 227. Cross-reference: See also ch. NR 140, Wis. adm. code.
160.23 Implementation of responses for specific sites; preventive action limits. (1) If the concentration of a substance in groundwater attains or exceeds a preventive action limit at a point of standards application, the regulatory agency shall assess the cause of the increased concentration, taking into account background concentrations, if known, and other known or suspected contributors in the area and shall evaluate the significance of the concentration of the substance and shall implement responses for a specific site designed to: (a) Minimize the concentration of the substance in the groundwater at the point of standards application where technically and economically feasible; (b) Regain and maintain compliance with the preventive action limit, unless, in the determination of the regulatory agency, the preventive action limit is either not technically or economically feasible, in which case, it shall achieve compliance with the lowest possible concentration which is technically and economically feasible; and (c) Ensure that the enforcement standard is not attained or exceeded at the point of standards application. (2) A regulatory agency shall take responses with respect to a specific site in accordance with rules promulgated under s. 160.21.
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(4) The regulatory agency may not impose a prohibition on the substance or the activity or practice which uses or produces the substance unless the regulatory agency: (a) Bases its decision upon reliable test data; (b) Determines, to a reasonable certainty, by the greater weight of the credible evidence, that no other remedial action would prevent the violation of the enforcement standard at the point of standards application; (c) Establishes the basis for the boundary and duration of the prohibition; and (d) Ensures that any prohibition imposed shall be reasonably related in time and scope to maintaining compliance with the enforcement standard at the point of standards application. (6) (a) A regulatory agency shall consider the existence of the background concentration of a naturally occurring substance in evaluating response options to the noncompliance with a preventive action limit for that substance. Before a regulatory agency may order a remedial action under sub. (2) or issue a prohibition for a specific site where the background concentration of a substance is determined to be equal to or greater than the preventive action limit, the regulatory agency shall determine that the proposed remedial action will result in the protection of or substantial improvement in groundwater quality notwithstanding the background concentrations of naturally occurring substances. (b) Paragraph (a) does not apply to a substance which may be carcinogenic, teratogenic or mutagenic in humans. (7) If the concentration of a substance in groundwater attains or exceeds a preventive action limit at a point of standards application and if a waste facility subject to the waste management fund incurs costs for repairing environmental damage which arises from these occurrences which are not anticipated in the plan of operation and which poses a substantial hazard to public health or welfare, those costs may be paid as provided under s. 289.68. (8) An action under this section with respect to a specific site does not constitute a major state action under s. 1.11 (2). History: 1983 a. 410; 1989 a. 56; 1995 a. 227.
160.25 Implementation of responses for specific sites; enforcement standards. (1) (a) If an activity or practice is not subject to regulation under chs. 283 or 289 to 292 and if the concentration of a substance in groundwater attains or exceeds an enforcement standard at a point of standards application, the regulatory agency shall take the following responses unless it can be shown to the regulatory agency that, to a reasonable certainty, by the greater weight of the credible evidence, an alternative response will achieve compliance with the enforcement standard at the point of standards application: 1. Prohibit the activity or practice which uses or produces the substance; and 2. Implement remedial actions with respect to the specific site in accordance with rules promulgated under s. 160.21. (b) A regulatory agency shall impose a remedial action for a specific site which is reasonably related in time and scope to the substance, activity or practice which caused the enforcement standard to be attained or exceeded at the point of standards application. (2) If a facility is subject to regulation under chs. 283 or 289 to 292 and if the concentration of a substance in groundwater attains or exceeds an enforcement standard at a point of standards application, the department shall require remedial actions for a specific site in accordance with rules promulgated under s. 160.21 as are necessary to achieve compliance with the enforcement standard at the point of standards application. (3) If nitrates or any substance of aesthetic concern only at-
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tains or exceeds an enforcement standard, the regulatory agency is not required to impose a prohibition or close a facility if it determines that: (a) The enforcement standard was attained or exceeded, in whole or in part, because of high background concentrations of the substance; and (b) The additional concentration does not represent a public welfare concern. (4) If compliance with the enforcement standard is achieved at the point of standards application, s. 160.23 applies. (5) (a) A regulatory agency shall consider the existence of background concentrations of naturally occurring substances in evaluating response options to the noncompliance with an enforcement standard for that substance. A regulatory agency may not order remedial action under sub. (1) or (2) at a site where the background concentration of a substance is determined to be equal to or greater than the preventive action limit, unless the regulatory agency determines that the proposed remedial action will result in the protection of or substantial improvement in groundwater quality notwithstanding the background concentrations of naturally occurring substances. (b) Paragraph (a) does not apply to a substance which is carcinogenic, teratogenic or mutagenic in humans. (6) If the concentration of a substance in groundwater attains or exceeds an enforcement standard at a point of standards application and if a waste facility subject to the waste management fund incurs costs for repairing environmental damage which arises from those occurrences which are not anticipated in the plan of operation and which poses a substantial hazard to public health or welfare, those costs may be paid as provided under s. 289.68. (7) An action under this section with respect to a specific site does not constitute a major state action under s. 1.11 (2). History: 1983 a. 410; 1995 a. 227.
160.255 Exceptions for private on-site wastewater treatment systems. (1) In this section, “private on-site wastewater treatment system” has the meaning given in s. 145.01 (12). (2) Notwithstanding s. 160.19 (1), (2) and (4) (b), a regulatory agency is not required to promulgate or amend rules that define design or management criteria for private on-site wastewater treatment systems to minimize the amount of nitrate in groundwater or to maintain compliance with the preventive action limit for nitrate. (3) Notwithstanding s. 160.19 (3), a regulatory agency may promulgate rules that define design or management criteria for private on-site wastewater treatment systems that permit the enforcement standard for nitrate to be attained or exceeded at the point of standards application. (4) Notwithstanding s. 160.21, a regulatory agency is not required to promulgate rules that set forth responses that the agency may take, or require to be taken, when the preventive action limit or enforcement standard for nitrate is attained or exceeded at the point of standards application if the source of the nitrate is a private on-site wastewater treatment system. (5) Notwithstanding ss. 160.23 and 160.25, a regulatory agency is not required to take any responses for a specific site at which the preventive action limit or enforcement standard for nitrate is attained or exceeded at the point of standards application if the source of the nitrate is a private on-site wastewater treatment system. History: 1995 a. 27; 2011 a. 146.
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160.257 Exceptions for aquifer storage and recovery systems. (1) In this section: (a) “Aquifer storage and recovery system” means all of the aquifer storage and recovery wells and related appurtenances that are part of a municipal water system. (b) “Aquifer storage and recovery well” means a well through which treated drinking water is placed underground for the purpose of storing and later recovering the water through the same well for use as drinking water. (c) “Municipal water system” means a community water system, as defined in s. 281.62 (1) (a), that is owned by a city, village, town, county, town sanitary district, utility district, public inland lake protection and rehabilitation district, or municipal water district, or by a privately owned water utility serving any of the foregoing. (d) “Specified substance” means one of the following: 1. Chloroform. 2. Bromodichloromethane. 3. Dibromochloromethane. 4. Bromoform. (e) “Treated drinking water” means potable water that has been treated so that it complies with the primary drinking water standards promulgated under ss. 280.11 and 281.17 (8). (2) Notwithstanding s. 160.19 (1) and (2), the department is not required to promulgate or amend rules that define design or management criteria for aquifer storage and recovery systems to minimize the amount of a specified substance in groundwater or to maintain compliance with the preventive action limit for a specified substance, however, the department shall promulgate rules that define design or management criteria for aquifer storage and recovery systems to maintain compliance with drinking water standards promulgated under ss. 280.11 and 281.17 (8). (3) Notwithstanding s. 160.21 (2), the point of standards application for an aquifer storage and recovery well with respect to a specified substance is 1,200 feet from the aquifer storage and recovery well and at any other well that is within 1,200 feet from the aquifer storage and recovery well. History: 2001 a. 109.
160.26 Enforcement. Regulatory agencies shall enforce the provisions of this chapter in accordance with enforcement procedures and subject to the penalties established by statute for activities and practices regulated by the regulatory agency. History: 1983 a. 410.
160.27 Substances in groundwater; monitoring. (1) The department, with the advice and cooperation of other agencies and the groundwater coordinating council, shall develop and operate a system for monitoring and sampling groundwater to determine whether substances identified under s. 160.05 (1) are in the groundwater or whether preventive action limits or enforcement standards are attained or exceeded at points of standards application. (2) At a minimum, the monitoring system shall include the following components: (a) Problem assessment monitoring to detect substances in the groundwater, including substances identified under s. 160.05 (1), and to assess the significance of the concentrations of the detected substances; (b) Regulatory monitoring to determine if preventive action limits or enforcement standards are attained or exceeded and to obtain information necessary for the implementation of responses with respect to specific sites under ss. 160.21, 160.23 and 160.25; (c) At-risk monitoring to define and sample at-risk potable
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wells in areas where substances identified under s. 160.05 (1) are detected in the groundwater or where preventive action limits or enforcement standards are attained or exceeded; (d) Management practice monitoring for establishing the management practices necessary to meet the requirements of ss. 160.19 and 160.21. The regulatory agency responsible for a particular management practice has primary responsibility for monitoring that practice and the department shall ensure that the monitoring specifications meet the needs of the regulatory agency; and (e) A monitoring plan for collecting, managing and coordinating the monitoring components specified under pars. (a) to (d) with the monitoring information from other regulatory agencies. (3) The department shall notify the regulatory agency and the department of health services when monitoring data indicate that: (a) A substance is detected in groundwater; (b) The concentration of a substance, by a reasonable degree of scientific certainty, is determined to be changing; or (c) The concentration of a substance attains or exceeds a preventive action limit or an enforcement standard at a point of standards application. (4) The department shall coordinate the collection of groundwater monitoring data and the exchange of these data among agencies for the purpose of this chapter and shall ensure, with the advice and cooperation of other agencies, the technical accuracy of the monitoring data used in the administration of this chapter. (5) Notwithstanding subs. (1) to (3), a regulatory agency may develop and operate a system for monitoring and sampling groundwater to determine compliance with this chapter. This section does not affect the authority of the department to require groundwater monitoring by owners or operators of solid or hazardous waste facilities, water systems or wastewater systems under chs. 280 to 285 or 289 to 299. (6) The department shall notify the owner of any potable well and the occupant of any residence served by that well of the results of any monitoring data it obtains from samples of water from that well. History: 1983 a. 410; 1995 a. 27 s. 9126 (19); 1995 a. 227, 378; 1997 a. 35; 2005 a. 347; 2007 a. 20 s. 9121 (6) (a). Cross-reference: See also ch. NR 141, Wis. adm. code. NOTE: 2005 Wis. Act 347, which affected this section, contains extensive explanatory notes.
160.29 Petitioning for rule making. (1) Where the department finds that a preventive action limit or an enforcement standard for a substance is, or will be, attained or exceeded at points of standards application at numerous locations, and that adoption or revision of rules under s. 160.19 or 160.21 by the regulatory agency is an appropriate response, the department may submit a petition for rule making to the regulatory agency. The petition shall include all of the following: (a) The reason for the request for rule making by the department. (b) The research or monitoring data supporting the finding by the department that the preventive action limit or the enforcement standard for a substance is, or will be, attained or exceeded at the points of standards application. (c) A recitation of the authority of the regulatory agency to regulate the substance. (2) Within 120 days after receipt of a petition under this section, the regulatory agency either shall deny the petition in writing or shall submit to the department a proposed timetable for the revision or promulgation of the requested rules and proceed with rule making under subch. II of ch. 227. Failure of the agency to
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respond to the petition within 120 days constitutes denial of the petition. (3) Section 227.12 does not apply to petitions under this section. History: 1983 a. 410; 1985 a. 182 s. 57.
160.31 Legislative review. Nothing in this chapter affects the legislative review of any proposed rule relating to animal waste treatment, under s. 13.565. History: 1983 a. 410.
160.32 Common law and liability. (1) COMMON LAW UNAFFECTED. Nothing in this chapter restricts or abrogates any remedy which any person or class of persons may have under other statutory or common law. (2) NO ADMISSION OF LIABILITY. A response at a specific site taken by any person under s. 160.23 or 160.25 is not evidence of liability or an admission of liability for any potential or actual environmental pollution, as defined under s. 299.01 (4). History: 1983 a. 410; 1995 a. 227.
160.33 Public participation. Each regulatory agency shall promulgate rules which provide for public participation in the issuance and administrative enforcement by the regulatory agency of any special order adopted pursuant to the requirements of this chapter. History: 1983 a. 410.
160.34 No mandatory well repair as a condition for testing. No regulatory agency may require as a condition for the testing of a private water system at the request of the owner that the owner agree to institute changes necessary to bring the construction or design of the water system into compliance with administrative rules in effect at the time of testing but not in effect prior to 1954. History: 1983 a. 410; 1995 a. 378.
160.36 Cooperation with American Indian tribes and bands. (1) REQUIREMENT TO COOPERATE. The department shall cooperate with American Indian tribes and bands with the approval of the tribal governing body, for the purposes specified in this section. (2) AGREEMENTS REGARDING MONITORING. The department may negotiate and enter into cooperative agreements with American Indian tribes and bands for the purposes of: (a) Providing advice and assistance to American Indians who wish to establish a groundwater monitoring program on the lands of any American Indian tribe or band. (b) Obtaining for state use any information on groundwater quality which results from a monitoring program conducted by American Indians. (c) Using state resources to conduct groundwater monitoring on the lands of any American Indian tribe or band. (d) Sharing with an American Indian tribe or band the results of groundwater monitoring conducted by the department, by a regulatory agency or by the geological and natural history survey which relate to the potential contamination of groundwater under the lands of an American Indian tribe or band. (3) AGREEMENTS REGARDING ENFORCEMENT. The department may negotiate and enter into cooperative agreements with American Indian tribes and bands for the following purposes: (a) Providing advice and assistance to American Indians who wish to establish groundwater regulatory programs on the lands of any American Indian tribe or band. (b) Using state resources to conduct regulatory activities on the lands of an American Indian tribe or band. History: 1983 a. 410.
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Groundwater coordinating council. (1) GENThe groundwater coordinating council shall serve as a means of increasing the efficiency and facilitating the effective functioning of state agencies in activities related to groundwater management. The groundwater coordinating council shall advise and assist state agencies in the coordination of nonregulatory programs and the exchange of information related to groundwater, including, but not limited to, agency budgets for groundwater programs, groundwater monitoring, data management, public information and education, laboratory analysis and facilities, research activities and the appropriation and allocation of state funds for research. (1m) FUNDING FOR GROUNDWATER RESEARCH. The groundwater coordinating council shall advise the secretary of administration on the allocation of funds appropriated to the board of regents of the University of Wisconsin System under s. 20.285 (1) (a) for groundwater research. ERAL FUNCTIONS.
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(2) SUBCOMMITTEES. The groundwater coordinating council may create subcommittees to assist in its work. The subcommittee members may include members of the council, employees of the agencies with members on the council, employees of other state agencies, representatives of counties and municipalities and public members. The council shall consider the need for subcommittees on the subjects within the scope of its general duties under sub. (1) and other subjects deemed appropriate by the council. (3) REPORT. The groundwater coordinating council shall review the provisions of 1983 Wisconsin Act 410 and report to the chief clerk of each house of the legislature, for distribution to the legislature under s. 13.172 (2), concerning the implementation of the act by January 1, 1989. History: 1983 a. 410; 1987 a. 186; 1989 a. 31.
May 22, 2026, are designated by NOTES. (Published 5-22-26)