Wisconsin Administrative Code
Department of Agriculture, Trade and Consumer Protection
ATCP 20-54 - Agricultural Resource Management
Chapter ATCP 31 - Groundwater protection program
Section ATCP 31.08 - Prohibitions against pesticide use

Universal Citation: WI Admin Code ยง ATCP 31.08

Current through August 26, 2024

(1) SITE-SPECIFIC PROHIBITION IN RESPONSE TO GROUNDWATER CONTAMINATION WHICH EXCEEDS AN ENFORCEMENT STANDARD. If, at a point of standards application, the concentration of a pesticide substance in groundwater attains or exceeds an enforcement standard, and if the concentration has resulted from or may be affected by a pesticide use, the department shall, as a site-specific response under s. ATCP 31.07, prohibit the pesticide use on a site-specific basis unless the department is shown, and determines to a reasonable certainty by the greater weight of the credible evidence, that an alternative response will achieve compliance with the enforcement standard. The scope and duration of the site-specific prohibition shall be reasonably designed to achieve and maintain compliance with the enforcement standard at the point of standards application, and at other downgradient points to which the pesticide substance may migrate. A prohibition may remain in effect indefinitely unless the department is shown, and determines, that resumption of the pesticide use is not likely to cause a renewed or continued violation of the enforcement standard. The department's responsibility to initiate a site-specific prohibition under s. 160.25, Stats., and this subsection is not affected by sub. (2), or by contemporaneous findings that concentrations of the same pesticide substance at other points of standards application fall below the enforcement standard.

(2) SITE-SPECIFIC PROHIBITION IN RESPONSE TO GROUNDWATER CONTAMINATION WHICH EXCEEDS A PREVENTIVE ACTION LIMIT, BUT NOT AN ENFORCEMENT STANDARD. If, at a point of standards application, the concentration of a pesticide substance in groundwater attains or exceeds a preventive action limit but not an enforcement standard, the department may not implement a site-specific response under s. ATCP 31.07 prohibiting a pesticide use unless the department:

(a) Determines, pursuant to s. 160.23(4), Stats., that no less restrictive response would prevent the violation of an enforcement standard at the point of standards application.

(b) Establishes the basis for the geographic scope and duration of the prohibition; and

(c) Limits the scope and duration of the prohibition to that which is reasonably necessary to maintain compliance with the enforcement standard at the point of standards application.

(3) STATEWIDE OR REGIONAL PROHIBITION. The department may, by rule under s. ATCP 31.09, prohibit a pesticide use on a statewide or regional basis, as well as on a site-specific response basis, if the department does all of the following:

(a) Determines that groundwater contamination has occurred or is likely to occur on a statewide or regional basis as a result of the pesticide use.

(b) Determines that a statewide or regional prohibition is necessary to achieve or maintain compliance with an enforcement standard. In determining the need for a statewide or regional prohibition, the department shall consider:
1. The extent, age, reliability, and geographical distribution of groundwater sample test data; and

2. The extent to which local conditions and circumstances can reliably be considered characteristic of a larger region, or of the state as a whole.

(c) Determines that compliance with the enforcement standard cannot reasonably be achieved and maintained by other, less restrictive measures.

(d) Establishes the basis for the scope and duration of the prohibition.

(e) Limits the scope and duration of the prohibition to that which is reasonably necessary to achieve and maintain compliance with the enforcement standard.

(4) REPEALING A SITE-SPECIFIC PROHIBITION.

(a) The department may repeal or modify a site-specific prohibition under sub. (1) if all of the following conditions are met:
1. Tests on at least 3 consecutive groundwater samples, drawn from each point of standards application in the prohibition area at which the concentration of the pesticide substance previously attained or exceeded the enforcement standard, show that the concentration of that pesticide substance at that point of standards application has fallen to and remains at a level which is at or below the level specified by the department under par. (c). The 3 consecutive samples shall be collected from each point of standards application at intervals of at least 6 months, with the first sample being collected at least 6 months after the effective date of the site-specific prohibition. A monitoring well approved by the department may be substituted for any point of standards application which is no longer available for testing, provided that the monitoring well qualifies as a point of standards application under s. ATCP 31.03.

2. Tests of groundwater samples drawn from other points of standards application in the prohibition area during the retesting period under subd. 1., if any, reveal no other concentrations of the pesticide substance that exceed the level specified by the department under par. (c).

3. The department determines, based on credible scientific evidence, that renewed use of the pesticide in that prohibition area is not likely to cause a renewed violation of the enforcement standard.

Note: If a site-specific prohibition is created by rule, it can only be repealed or modified by rule. If a site-specific prohibition is created by special order under s. 94.71(3) (c), Stats., it can only be repealed or modified by special order. This subsection establishes conditions which must be met before the department adopts a rule or issues a special order repealing or modifying a site-specific prohibition. The subsection does not, by itself, repeal or modify any site-specific prohibition.

The department plans to continue its program of groundwater research, and will continue to monitor groundwater in areas where there is significant potential for repealing or modifying a prohibition. However, the department is not legally obligated to conduct specific groundwater research or perform specific groundwater tests at the request of a person who wishes to have a site-specific prohibition repealed or modified.

The department may accept test results from other sources if the department considers those test results reliable. Persons who question the reliability of test results used to maintain, modify or repeal a prohibition may submit information showing why the test results are unreliable. If the department finds that there are reasonable grounds to question the reliability of any test result, the department will attempt to perform additional sampling and testing to verify the test result.

(b) As a condition to repealing or modifying a site-specific prohibition under par. (a), the department may do any of the following:
1. Provide for continued groundwater monitoring at points of standards application where the concentration of the pesticide substance previously attained or exceeded the enforcement standard, or at monitoring wells substituted for those points of standards application under par. (a) 1. At a minimum, groundwater from those points of standards application or monitoring wells shall be sampled and tested during the second and fifth years after the department repeals a site-specific prohibition.

2. Impose pesticide use modifications that are reasonably designed to achieve and maintain compliance with the preventive action limit at all points of standards application in the prohibition area where concentrations of the pesticide substance attained or exceeded that limit, and at all downgradient points to which that pesticide substance may migrate from those points of standards application. The department may continue to prohibit pesticide use in portions of the original prohibition area where, because of conditions unique to those smaller areas, a prohibition is justified under sub. (2).

Note: For example, as a condition to repealing a pesticide use prohibition, the department may limit pesticide application rates and methods of application where appropriate, to achieve and maintain compliance with the preventive action limit. The department may continue to prohibit pesticide use in portions of the original prohibition area where, because of conditions unique to those smaller areas (e.g., unique soil types), nothing short of a prohibition will prevent a renewed violation of the enforcement standard.

The repeal of a prohibition area does not affect any responsibility which the department has under s. ATCP 31.07 to take other appropriate action to minimize the concentration of the pesticide substance where technically and economically feasible, and to restore and maintain compliance with the preventive action limit. The department may also reinstate a repealed prohibition area if groundwater testing at a point of standards application shows an increasing trend of pesticide contamination, suggesting that contamination may again attain or exceed the enforcement standard.

(c) The department shall by rule specify a level to which concentrations of a pesticide substance must fall before the department may repeal or modify a site-specific prohibition under par. (a). The specified level shall be sufficiently below the enforcement standard so that, when groundwater test results under par. (a) 1. and 2. fall at or below the specified level, the department can reasonably conclude that groundwater concentrations in the prohibition area are below and can be expected to remain below the enforcement standard.

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