Recommended Groundwater Enforcement Standards

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The DNR will be having a public comment period. To learn more about the rule-making process and how to submit comments, go to DNR's Summary of Wisconsin's Groundwater Rule webpage.

In Wisconsin, state groundwater standards are used to protect and ensure clean groundwater resources. More than two-thirds of Wisconsin residents use groundwater for their drinking water, whether through a private well or public water system. The development of state groundwater standards is a collaborative process involving multiple state agencies.

Our primary responsibility is to develop groundwater standard recommendations for substances that represent a public health concern (when requested by the Wisconsin Department of Natural Resources). The Department of Natural Resources can propose rules these new or revised standards based on DHS recommendations. Check out our Protecting Groundwater fact sheet to understand more about the DHS process.

The table below summarizes our recommendations for groundwater enforcement standards and preventive action limits that were provided to the Department of Natural Resources on June 21, 2019. In the coming months, there will be a period for the public to give input on these proposed standards to the Department of Natural Resources.

Recommendation Table

Substance New or Existing

Enforcement Standard
Recommended Value

Preventive Action Limit
Recommended Value

1,1-Dichloroethane Existing No change 850 µg/L No change 85 µg/L
1,2,3-Trichloropropane Existing   0.3 ng/L   0.03 ng/L
1,4-Dioxane Existing   0.35 µg/L   0.035 ng/L
Aluminum Existing No change 200 µg/L No change 20 µg/L
Bacteria (E. coli) New n/a 0 n/a 0
Bacteria (total coliform) Existing No change 0 No change 0
Barium Existing No change 2,000 µg/L No change 400 µg/L
Boron Existing   2,000 µg/L   400 µg/L
Clothianidin New n/a 1,000 µg/L n/a 200 µg/L
Cobalt Existing No change 40 µg/L   4 µg/L (ii)
Dacthal MTP (monomethyl tetrachloroterephthalic acid) and
Dacthal TPA (tetrachloroterephthalic acid) (i)
New n/a 70 µg/L   7 µg/L (ii)
Glyphosate New n/a 10 mg/L n/a 1 mg/L
Glyphosate AMPA (aminomethylphosphonic acid) New n/a 10 mg/L n/a 2 mg/L
Hexavalent chromium New n/a 70 ng/L n/a 7 ng/L
Imidacloprid New n/a 0.2 µg/L n/a 0.02 µg/L
Isoxaflutole and
Isoxaflutole diketonitrile (DKN)
New n/a 3 µg/L n/a 0.3 µg/L
Isoxaflutole benzoic acid (BA) New n/a 800 µg/L n/a 160 µg/L
Molybdenum Existing No change 40 µg/L   4 µg/L (ii)
PFOA (perfluorooctanoic acid) and
PFOS (perfluorooctane sulfonic acid)
New n/a 20 ng/L n/a 2 ng/L
Strontium New n/a 1,500 µg/L n/a 150 µg/L
Sulfentrazone New n/a 1,000 µg/L n/a 100 µg/L
Tetrachloroethylene (PCE) Existing   20 µg/L   2 µg/L
Thiamethoxam New n/a 100 µg/L n/a 10 µg/L
Thiencarbazone-methyl New n/a 10 mg/L n/a 2 mg/L
Trichloroethylene (TCE) Existing   0.5 µg/L   0.05 µg/L

i. These substances are combined with dacthal’s existing enforcement standard.
ii. Although DHS is not recommending a change in the enforcement standard for this substance, we are recommending a change in the preventive action limit.


1 µg/L (microgram per liter) = One part per billion (ppb)
1 ng/L (nanogram per liter) = One part per trillion (ppt)
1 mg/L (milligram per liter) = One part per million (ppm)

See our chemical webpage for more information on conversions.


  • Enforcement standard - level of a substance in groundwater that is used to protect public health or welfare and the level at which the sources of the substance might be regulated.
  • Preventive action limit - level of a substance in groundwater that is used by regulatory agencies to determine when action may be needed so that levels do not reach or exceed the enforcement standard.
  • Carcinogen: Cancer causing
  • Mutagenic: Causes birth defects
  • Teratogenic: Causes DNA damage
  • Interactive effects: Can affect the toxicity of another substance or its toxicity can be affected by another substance.


Last Revised: June 25, 2019