Waukesha Water Diversion

The City of Waukesha is seeking to divert an average of 10.1 million gallons/day, and up to peak of 16.7 million gallons, of water from Lake Michigan for itself and surrounding areas.[1]

Currently, Waukesha obtains its water from a mix of local sources, including shallow groundwater wells and wells pumping the deep St. Peter Sandstone aquifer. Water quality from the deep aquifer has fallen however, as the water level has declined over the last 100 years due to overpumping by Waukesha and other users. Waukesha is under a court order to provide water that complies with radium standards by 2018, be it through additional filtering of its current sources of water supply or by developing a different radium-compliant source.[1]

Since Waukesha is in a county that straddles the line of the Great Lakes Basin, the proposed diversion must comply with rules the Great Lakes Compact, an agreement among the Great Lakes Basin States that details how they will manage and protect the waters of the Great Lakes Basin, including through the strict regulation of diversions out of the Great Lakes.

Key Points

  • Waukesha is the first community that lies entirely outside of the Great Lakes Basin to apply to divert water out of the Great Lakes under the Compact.
  • As the first application under the Compact, Waukesha’s application will set the precedent by which all future applications will be judged.
Clean Wisconsin's Work

Clean Wisconsin is working to ensure that this application and the Wisconsin Department of Natural Resources’ process to consider the application both meet the standards in the Great Lakes Compact. We are concerned about the precedent this application could have for other possible diversion requests in Wisconsin and in other states in the future. On this effort, we work in close collaboration with a coalition of five other Wisconsin environmental conservation organizations known as the Compact Implementation Coalition.

Clean Wisconsin Media and Materials

Questions and Answers

What is the Great Lakes Compact? 
The Great Lakes Compact is an agreement between the eight Great Lakes states that details how to use, manage and protect the Great Lakes Basin’s water supply. It is accompanied by a parallel international agreement that also involves the two Canadian Great Lakes provinces. The Great Lakes Compact aims to minimize the impacts of changes to water flow, quality and quantity on the Great Lakes by limiting diversions (taking water out of the basin) and regionally managing the lakes as a whole system.[2]

Who can qualify for a diversion?
Communities that are “straddling communities” or “communities within a straddling county” can qualify for a diversion for public water supply under the compact. A straddling community is a town, city, or village that lies partly within the Great Lakes Basin. A community within a straddling county is a town, city or village that lies entirely outside of the basin, but wholly within a straddling county. These communities would be allowed to obtain a diversion of basin water provided they meet certain strict criteria.[3] Waukesha is a community within a straddling county, because it is located outside the Great Lakes Basin but is entirely within Waukesha County, which straddles the divide between the Great Lakes and Mississippi River basins.

Why is Waukesha proposing to draw water from the Great Lakes Basin?
Waukesha currently draws much of its water supply from a deep sandstone aquifer that has slowly been drawn down to significantly lower levels, due to pumping by Waukesha and many other local communities over decades. As the levels in the deep sandstone aquifer have dropped, the water quality in the aquifer has diminished. As a result water supplied by the Waukesha Water Utility, particularly on “peak days,” can suffer from poor quality.
One deep sandstone aquifer water quality challenge that has emerged for many Southeastern Wisconsin communities in recent years as the aquifer declined is radium in the water. Radium is a radioactive decay product of uranium and thorium that occurs naturally in the environment. It is present in almost all water, soil and rocks, but usually in small amounts.[4] When groundwater moves past or through rock formations containing radium, some of the minerals in the rock dissolve; as a result, the groundwater picks up radium.[5] Radium at high levels is considered a human health hazard. Many Wisconsin communities and numerous others across the country manage radium in their water supply to safe, low levels.

Why is Clean Wisconsin opposed to Waukesha’s diversion application? 
Waukesha is the first community to submit an application of this type to divert water out of the Great Lakes Basin. As a result, it will set the precedent for all future applications across the basin. Some concerns about Waukesha’s current application include:

  • The application does not show that there is no reasonable alternative to provide safe and adequate water without using Lake Michigan water.
  • The application requests water resources for an area that is significantly larger than the current service area, including for areas that do not have water quantity or quality concerns.
  • Waukesha has not implemented all of the water conservation and efficiency measures required by Wisconsin law and the Compact.
  • The application’s proposed scheme for managing water and returning it to the Great Lakes would not minimize the amount of Mississippi Basin water that would be sent into the Great Lakes Basin.
  • The application does not prove that water returned after treatment to Lake Michigan will be treated to Clean Water Act standards.[5]

What other sources of clean water supply are available to Waukesha, other than water from Great Lakes Basin?
Waukesha has many potential sources of clean water supply. These include:

  • Using existing technologies to remove radium safely from current supplies for drinking water purposes.
  • There is a shallow glacial aquifer in the Waukesha area with significant water supply potential.
  • The Fox River, which serves as the source of water supply for some communities downstream in Illinois, runs through Waukesha and could play at least a partial role in future water supply for the city.
  • Water conservation and efficiency measures can (and must, under the Compact) be considered a source of supply in their own right.
  • Waukesha could use a combination of the various sources above to meet its water needs.

Waukesha would prefer to draw its water supply from Lake Michigan for reasons it lays out in great detail in its application to the Wisconsin Department of Natural Resources. The Department of Natural Resources is working to review and evaluate that application so  it can decide whether or not the proposal passes muster under Wisconsin law and the Great Lakes Compact.

What criteria must be met in order for a straddling county community’s request for a diversion to comply with the Compact? 
In order to comply with the Great Lakes Compact as administered through Wisconsin law, the following criteria must be met:[6]The water is used solely for public water supply purposes;

  • The community is otherwise without an adequate supply of potable water;
  • The diversion meets the exception standard described in sections 281.343 (4n)(d) and 281.346 (4)(f) of the Wisconsin Statutes;
  • The proposal maximizes the amount of diverted water that is returned to the Great Lakes basin and minimizes the amount of water that originated outside of the basin that is returned to the Great Lakes basin;
  • There is no reasonable water supply alternative in the basin in which the community is located (in Wisconsin, that would be the upper Mississippi River basin), including conservation of existing water supplies;
  • The proposal will not endanger the integrity of the Great Lakes basin ecosystem based upon a determination that the proposal will have no significant adverse impact on the Great Lakes basin ecosystem;
  • The proposal is consistent with an approved water supply service area plan under section 281.348 of the Wisconsin Statutes that covers the public water supply system;
  • The proposal is reviewed by the regional body (the Governors of the eight Great Lakes States and the premiers of the provinces of Ontario and Quebec in Canada); and
  • The proposal is approved by the Great Lakes St. Lawrence River Basin Water Resources Council (consisting of the Governors of the eight Great Lakes States) with no disapproving votes.

How would Waukesha obtain the desired water from Lake Michigan? 
 In late 2012, Waukesha struck a deal with Oak Creek to supply Waukesha with water if its application for a diversion is approved by Wisconsin and the other Great Lakes states.

Where would the wastewater go? 
In order to comply with the compact, Waukesha would have to return all diverted water (less any losses to consumptive use) back to the Lake Michigan Basin. Waukesha’s application suggests that they would prefer to send treated wastewater back to the Lake Michigan via the Root River, which flows through the city of Racine into Lake Michigan.[1] Other options evaluated in the application, and which Wisconsin’s Department of Natural Resources will look at closely, include return through the Milwaukee Metropolitan Sewerage District (whose regional sewage interceptors run relatively close to Waukesha to serve nearby communities within the basin), and the possibility of a direct pipe to the lake. Environmental impacts on a possible return through a natural stream system will surely be a factor in the Wisconsin Department of Natural Resources’ ultimate decision on this issue.

Quick Facts

Waukesha’s Current Water Supply

  • The Waukesha Water Utility currently supplies 6.9 million gallons of water per day, from 10 functional wells: 7 in a deep aquifer and three in a shallow aquifer. [1]
  • Approximately 85% of Waukesha’s water supply comes from the deep St. Peter Sandstone aquifer.[1]
  • Currently, 3 out of Waukesha’s 7 active deep aquifer wells feature radium removal.[1]

Radium Standards

  • The Maximum Contaminant Level (MCL) standards relevant to radium contamination in drinking water are 15 picocuries per liter (pCi/L) for “gross alpha” and 5 pCi/L for “combined radium.”
  • Currently, the Waukesha Water Utility blends water from deep and shallow aquifers to meet the MCLs related to radium on a “weighted average” basis, in keeping with an agreement with the Wisconsin Department of Justice.[7]
  • Waukesha has until 2018 to meet the radium MCLs at all times and at all points that water enters the distribution system.[1]

2013 Diversion Application

  • The City of Waukesha is requesting a diversion of 10.1 million gallons per day of Great Lakes water.[1]
  • The diversion application submitted includes diversion of Great Lakes water for areas outside of the City of Waukesha, including parts of the Towns of Waukesha, Delafield, Genesee and the City of Pewaukee.[1]
  • The City of Waukesha proposes to send up to 6.75 million gallons per day of Mississippi river basin water to the Great Lakes.[1]
Wisconsin Data, Trends, and Legislation

In Wisconsin alone there are 17 counties that straddle Great Lakes basin boundaries. In 2000, communities within these counties but outside the basin (and thus potentially eligible to request diversions of Great Lakes water) had a combined population of 638,450 and covered 6,480 square miles.[8]

There is one other diversion currently approved in Wisconsin under the Compact: the city of New Berlin’s diversion, which diverts 2.142 million gallons/day from Lake Michigan to the straddling community of New Berlin and returns water via the Milwaukee Metropolitan Sewage District resulting in no net loss of water to the Great Lakes Basin.[9]

Current Law

See the Great Lakes Compact page for more information.


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Please cite this resource as: Clean Wisconsin, Inc. “Waukesha Water Diversion.” Clean Wisconsin Enviropedia. Retrieved from www.cleanwisconsin.org/enviropedia.