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.