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Great Lakes Compact and diversions

The Great Lakes Compact is a formal agreement between the Great Lakes states which details how the states will work together to manage and protect the Great Lakes-St. Lawrence River Basin. A parallel agreement (the Sustainable Water Resources Agreement) includes Ontario and Québec, the two Canadian provinces that border the Great Lakes and the St. Lawrence Seaway. Through these agreements, the states and provinces manage the water in the Great Lakes watershed collectively.

As part of the Great Lakes Compact, Wisconsin registers water withdrawals, receives and analyzes water use reports, requires water use permits, implements a conservation program and manages Great Lakes diversions.


The Great Lakes Compact became effective on Dec. 8, 2008, after final consent from the U.S. Congress [PDF exit DNR]. This date began the ban on diversions of water out of the basin, with limited exceptions. To implement the compact, Wisconsin passed implementing legislation [PDF exit DNR] in 2008 and has an active management program.

Two regional organizations oversee the implementation of the compact and the parallel agreement with the provinces.

Great Lakes diversion applications and approvals

The Great Lakes Compact and Agreement ban diversions of Great Lakes water with limited exceptions. These exceptions allow a "straddling community" or "community in a straddling county" to apply to divert water (i.e., to move water out of the Great Lakes Basin).

  • "Straddling community" — These communities straddle the Great Lakes Basin boundary. These are communities that lie partly within the Great Lakes Basin and partly outside of the Great Lakes Basin. Example of straddling community diversions are New Berlin and Mount Pleasant.
  • "Community in a straddling county" — These communities are wholly outside of the Great Lakes Basin, but located in a county that straddles the Great Lakes Basin boundary. An example of this type of community is Waukesha.

The table below summarizes diversion application requirements for a "straddling community" or "community in a straddling county."

Wisconsin and Great Lakes Compact requirements specified for a diversion approval Application Type
Straddling Community Straddling County
Application must be from a public water supply system Yes Yes
Diversion for public water supply purposes Yes Yes
All water returned less an allowance for consumptive use Yes Yes
The water will be treated to meet applicable permit requirements and to prevent the introduction of invasive species to the Great Lakes Basin. Yes Yes
Maximizes Great Lakes water returned to Great Lakes Basin and minimizes out of basin water returned Yes Yes
Requires a water conservation plan Yes Yes
Requires a water supply service area plan Yes
(see footnote 1)
Proposal meets Great Lakes Compact exception standard No
(see footnote 2)
Community without adequate supply of potable water No Yes
No reasonable water supply alternative including water conservation No Yes
The proposal will not endanger the integrity of the Great Lakes Basin and will have no significant adverse impacts on the Great Lakes No Yes
The proposal undergoes regional review No
(see footnote 3)
DNR conducts and publishes a formal technical review No
(see footnote 4)
The proposal requires approval by the Great Lakes Compact Council No Yes


  1. Unless the proposal is to provide water to a straddling community that includes an electronics and information technology manufacturing zone.
  2. Unless the diversion requires a new or increased withdrawal of Great Lakes water.
  3. Unless the diversion requires a new or increased withdrawal of Great Lakes water and the diversion will result in a consumptive use averaging 5 million gallons a day or more in any 90 day period.
  4. Unless proposal requires regional review.


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