Chapter ATCP 31

ATCP 31.07 Note 1. Review its rules governing pesticide use, pursuant to s. 160.19, Stats., and s. ATCP 31.09

ATCP 31.07 Note 2. Disseminate information concerning the groundwater contamination, and notify affected persons.

ATCP 31.07 Note 3. Notify state or local health authorities and county agricultural extension agents of the groundwater contamination.

ATCP 31.07 Note 4. Initiate or recommend further investigation or research concerning the groundwater contamination.

ATCP 31.07(3) (3) Site-specific response; maximum geographic scope. A site-specific response required under this section does not include a regulatory action which extends beyond the groundwater recharge zone of the aquifer from which the groundwater sample was collected at the point of standards application. If the pesticide substance has migrated, or may migrate through more than one aquifer, a site-specific response may extend, at a maximum, to the boundary of the outermost recharge zone providing recharge to an affected aquifer. If the natural boundary of a groundwater recharge zone is not readily definable, a site-specific response may extend, at a maximum, to the whole of every land parcel which, in the judgment of the department, may be wholly or partially located within the relevant groundwater recharge zone. All or a portion of any land parcel may be exempted from a site-specific response upon proof that the parcel or portion is located outside the groundwater recharge zone to which the site-specific response is applicable. Within the maximum geographic limits specified under this section, the department may determine the geographic scope of the site-specific response, based on the objective of restoring and maintaining compliance with the preventive action limit and minimizing the concentration of the pesticide substance in groundwater where technically and economically feasible, at the point of standards application and other downgradient points to which the pesticide substance may migrate. For purposes of administrative efficiency, the geographic scope of a site-specific response may be delineated according to a regular geometric pattern.

ATCP 31.07(4) (4) Site-specific responses; factors to be considered.

ATCP 31.07(4)(a) (a) In the department’s choice of a site-specific response, or in its adoption of substance-specific rules under s. ATCP 31.09 prescribing nondiscretionary site-specific responses, the department shall consider the general risks and benefits of the possible actions to the extent authorized by relevant law, and shall consider the following specific factors to the extent feasible:

ATCP 31.07(4)(a)1. 1. The concentration of the pesticide substance in groundwater at the point of standards application, and any known changes in concentration.

ATCP 31.07(4)(a)2. 2. The concentration of the pesticide substance at other points of standards application, if known, and any known changes in concentration.

ATCP 31.07(4)(a)3. 3. The extent, age and reliability of groundwater sample data indicating the presence of the pesticide substance in groundwater.

ATCP 31.07(4)(a)4. 4. The specific activities or practices from which the pesticide contamination originated, if known, and the locations at which the source activities or practices are conducted.

ATCP 31.07(4)(a)5. 5. The previously demonstrated propensity, if any, for the pesticide substance to leach to groundwater as a result of normal use.

ATCP 31.07(4)(a)6. 6. Environmental conditions which may reasonably affect the risk of groundwater contamination, including soil conditions, depth to groundwater, and subsurface geological conditions. Differences in local environmental conditions may not be used to justify a difference in site-specific responses between localities unless the differences in environmental conditions are reasonably known to affect the relative risk of groundwater contamination between localities.

ATCP 31.07(4)(a)7. 7. Differences in local pesticide use practices which are reasonably known to affect the risk of groundwater contamination.

ATCP 31.07(4)(a)8. 8. The environmental fate of the pesticide substance in soil and groundwater, to the extent known.

ATCP 31.07(4)(a)9. 9. The direction and rate of groundwater movement within the affected groundwater recharge zone, if known.

ATCP 31.07(4)(a)10. 10. The potential uses of the affected groundwater.

ATCP 31.07(4)(a)11. 11. The extent and likelihood of human exposure to the pesticide substance in groundwater.

ATCP 31.07(4)(a)12. 12. The alternative measures which are available to prevent or control groundwater contamination, the relative cost and effectiveness of each alternative, and the risks associated with each alternative including the risk of adverse environmental effects.

ATCP 31.07(4)(b) (b) Except as otherwise required by law, the department is not required to make a written record of its consideration under this subsection. This subsection may not be construed to limit the department’s responsibility under s. 160.19 or 160.25, Stats.

ATCP 31.07(5) (5) Site-specific response; prohibitions against pesticide use. If a site-specific response under this section prohibits a pesticide use in the locality covered by the site-specific response, the prohibition shall comply with the applicable provisions of s. ATCP 31.08.

ATCP 31.07 History History: Cr. Register, September, 1985, No. 357, eff. 10-1-85; correction in (2) (c) and (d) made under s. 13.93 (2m) (b) 7., Stats., Register, March, 1993, No. 447.

ATCP 31.08 ATCP 31.08 Prohibitions against pesticide use.

ATCP 31.08(1) (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.

ATCP 31.08(2) (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:

ATCP 31.08(2)(a) (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.

ATCP 31.08(2)(b) (b) Establishes the basis for the geographic scope and duration of the prohibition; and

ATCP 31.08(2)(c) (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.

ATCP 31.08(3) (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:

ATCP 31.08(3)(a) (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.

ATCP 31.08(3)(b) (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:

ATCP 31.08(3)(b)1. 1. The extent, age, reliability, and geographical distribution of groundwater sample test data; and

ATCP 31.08(3)(b)2. 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.

ATCP 31.08(3)(c) (c) Determines that compliance with the enforcement standard cannot reasonably be achieved and maintained by other, less restrictive measures.

ATCP 31.08(3)(d) (d) Establishes the basis for the scope and duration of the prohibition.

ATCP 31.08(3)(e) (e) Limits the scope and duration of the prohibition to that which is reasonably necessary to achieve and maintain compliance with the enforcement standard.

ATCP 31.08(4) (4) Repealing a site-specific prohibition.

ATCP 31.08(4)(a) (a) The department may repeal or modify a site-specific prohibition under sub. (1) if all of the following conditions are met:

ATCP 31.08(4)(a)1. 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.

ATCP 31.08(4)(a)2. 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).

ATCP 31.08(4)(a)3. 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.

ATCP 31.08 Note 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.

ATCP 31.08 Note 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.

ATCP 31.08 Note 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.

ATCP 31.08(4)(b) (b) As a condition to repealing or modifying a site-specific prohibition under par. (a), the department may do any of the following:

ATCP 31.08(4)(b)1. 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.

ATCP 31.08(4)(b)2. 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).

ATCP 31.08 Note 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.

ATCP 31.08 Note 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.

ATCP 31.08(4)(c) (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.

ATCP 31.08 History History: Cr. Register, September, 1985, No. 357, eff. 10-1-85; cr. (4), Register, March, 1998, No. 507, eff. 4-1-98.

ATCP 31.09 ATCP 31.09 Rulemaking to control pesticide contamination of groundwater; general.

ATCP 31.09(1) (1) Substance-specific rules. If an enforcement standard and preventive action limit are adopted by the department of natural resources for any pesticide substance, the department shall review its existing rules and adopt new or amended rules as necessary to comply with s. 160.19, Stats. The department may adopt rules on a substance-specific basis as appropriate, pursuant to ss. 94.69, 160.19, and 160.21, Stats. Except as otherwise provided under ch. 160, Stats., the rules shall be designed, to the extent technically and economically feasible, to minimize the level of the pesticide substance in groundwater and maintain compliance with the preventive action limit for the pesticide substance statewide. Rule provisions may apply on a statewide or localized basis, and on a temporary or permanent basis, as necessary to address varying state or local conditions.

ATCP 31.09(2) (2) Rule provisions. Substance-specific rules under this section may include:

ATCP 31.09(2)(a) (a) Prohibitions against the use of a pesticide, subject to s. ATCP 31.08.

ATCP 31.09(2)(b) (b) Limitations on the purposes for which a pesticide may be used, including limitations on the crops and target pests for which a pesticide may be used.

ATCP 31.09(2)(c) (c) Limitations on the rate at which a pesticide is applied.

ATCP 31.09(2)(d) (d) Limitations on the time or frequency of pesticide use.

ATCP 31.09(2)(e) (e) Limitations on the method of pesticide use.

ATCP 31.09(2)(f) (f) Reporting or permit requirements applicable to the use of a pesticide.

ATCP 31.09(2)(g) (g) Requirements for the training or certification of pesticide applicators or other persons using a pesticide.

ATCP 31.09(2)(h) (h) Required site-specific responses to be implemented by the department if an enforcement standard or preventive action limit for a pesticide substance is attained or exceeded at a point of standards application. Rules may specify the form and scope of the site-specific responses, and the specific conditions under which the site-specific responses are to be implemented.

ATCP 31.09(3) (3) Site-specific responses required by rule. Site-specific responses required by rule under this section shall comply with s. ATCP 31.07. Before adopting rules to require site-specific responses, the department shall consider the factors set forth under s. ATCP 31.07 (4), to the extent feasible. If, by rule, the department requires site-specific responses which will prohibit the use of a pesticide in affected localities, the rule shall comply with s. ATCP 31.08.

ATCP 31.09(4) (4) Scope of rulemaking authority; general. The section does not limit the department’s rulemaking authority under s. 94.69, 160.19 or 160.21, Stats. In the exercise of its rulemaking authority, the department may consider any information which may be relevant to the rulemaking proceeding, whether or not the information is derived from Wisconsin groundwater samples. The finding of a pesticide substance in groundwater, at a level which equals or exceeds an enforcement standard or preventive action limit, is not a prerequisite to the exercise of the department’s rulemaking authority under s. 94.69, 160.19 or 160.21, Stats.

ATCP 31.09 History History: Cr. Register, September, 1985, No. 357, eff. 10-1-85.