Adoption of rules for regulatory responses for groundwater contamination
Wis. Stat. § 160.21
in effect(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.
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 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.
Source: WI Statutes (Official Site)URL: https://docs.legis.wisconsin.gov/document/statutes/160.21Fetched: 10/7/2026