Substances in groundwater; monitoring
Wis. Stat. § 160.27
in effect(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 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.
Source: WI Statutes (Official Site)URL: https://docs.legis.wisconsin.gov/document/statutes/160.27Fetched: 10/7/2026