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Strengthening Illinois’ high-capacity well impact review process

Across northeastern Illinois, more than 1,700 high-capacity wells provide water for communities, businesses, industries, and many other users. Under the Water Use Act of 1983, Illinois defines a high‑capacity well as any well — or group of wells on the same property — with a combined pump capacity of 100,000 gallons per day or more. But groundwater is a shared and finite resource, and new withdrawals can affect nearby water users and the aquifers they rely on.

The Chicago Metropolitan Agency for Planning (CMAP) and Illinois-Indiana Sea Grant’s fourth Shared Waters, Shared Future workshop examines Illinois’ high-capacity well impact review process and how other states present opportunities to strengthen it.

Understanding Illinois’ current high-capacity well impact review process

Nora Beck, principal policy analyst at CMAP, provides an overview of Illinois’ high-capacity well impact review process, including how it was designed under the Water Use Act versus how it functions today. The process involves several agencies and is evaluates whether proposed high-capacity withdrawals could affect neighboring water users before wells are constructed.

Beck was joined by Gary Clark (Illinois Department of Natural Resources’ Office of Water Resources, retired), Dan Hadley (Illinois State Water Survey), and Chris Johnston (Illinois Environmental Protection Agency’s Division of Public Water Supplies), who each explain the history of the process and its different components

Illinois’ high-capacity well review process as designed

Under the Water Use Act, the process is intended to follow six-steps:

1. Propose a well: The property owner proposes a well that meets the high-capacity threshold.
2. Notify the county soil and water conservation district (SWCD): Before construction, the property owner or other responsible party submits information about the proposed well to the SWCD, including its characteristics, anticipated withdrawals, intended use, and nearby water users.
3. Notify local governments: The SWCD notifies local governments operating public water supply wells within one mile of the proposed high-capacity well.
4. Request technical review: The SWCD requests technical assistance from the Illinois State Water Survey and Illinois State Geological Survey.
5. Review potential effects: The proposed withdrawal is evaluated for potential impacts on other water users.
6. Share findings: The SWCD provides findings to the property owner, publishes an announcement in a local newspaper, and notifies affected local governments.

The review is intended to identify potential impacts before construction, but it does not issue an approval or denial of the proposed well. This impact review is separate from the construction permitting, public-health oversight, and water-use reporting processes that may also apply to a well. Those processes serve different purposes and do not substitute for evaluating potential impacts on other water users.

Beck explained that while Illinois has a statutory review framework, groundwater data, scientific expertise, and other well oversight processes, the formal impact review is not routinely completed. Dedicated funding for technical analysis ended in 1992. Even if it were fully implemented, the review would produce findings rather than approvals, denials, or conditions for withdrawals. It’s also not designed to comprehensively manage cumulative withdrawals or long-term groundwater sustainability.

Learning from other states

The workshop looks beyond Illinois to understand how other states evaluate and manage high-capacity water withdrawals. Speakers from Michigan and Iowa also share how the state’s approach works in practice and lessons learned through implementation.

Michigan’s approach

Jim Milne (Michigan Department of Environment, Great Lakes, and Energy) describes Michigan’s approach to reviewing large-quantity withdrawals. Michigan evaluates new or increased withdrawals over 100,000 gallons per day using its Water Withdrawal Assessment Tool. This tool evaluates potential impacts to streamflow and fish populations. Withdrawals that cannot pass the screening tool require additional review and authorization before pumping can begin. Michigan also tracks the cumulative effects of new large withdrawals at the subwatershed level. New or increased large-quantity withdrawals must be registered or otherwise authorized before pumping can begin.

Iowa’s approach

Michael Anderson (Iowa Department of Natural Resources) describes Iowa’s approach to reviewing large water withdrawals. Iowa requires permits for withdrawals exceeding 25,000 gallons in any single day. Those applications are reviewed for water availability, beneficial use, impacts on prior water users, and existing water allocations. Based on that review, Iowa can approve, modify, or deny an application.

Anderson highlights the use of pump-test data to better understand aquifer conditions and inform water-management decisions. He also describes Iowa’s more targeted management requirements for the heavily used Jordan Aquifer, including shorter permit periods, water-use restrictions, and measures tied to groundwater-level declines.

Comparing approaches across states

A panel discussion with representatives from Illinois, Iowa, and Michigan explored what the different approaches could teach Illinois about strengthening its high-capacity well impact review process. Several key lessons emerged:

Look beyond individual wells to understand broader impacts

Illinois’ review focuses on the potential impacts of individual wells or groups of wells on neighboring water users. Michigan and Iowa illustrate how considering cumulative withdrawals, connected surface waters, and stressed aquifers can provide a more complete picture of how new withdrawals can impact shared water resources.

Connect technical reviews to decision-making

Iowa and Michigan use review findings to inform decisions about whether proposed withdrawals can proceed, and under what conditions. Illinois’ review produces findings, but does not directly authorize, deny, or place conditions on withdrawals.

Sustain support for effective reviews and withdrawals

Michigan and Iowa have functioning review programs supported by dedicated staff, established technical procedures, and defined responsibilities for evaluating proposed withdrawals. Both states emphasize that reliable data, interagency coordination, adequate funding, and realistic review timelines are essential to keeping these programs working in practice.

Tailor approaches to different groundwater conditions

Michigan tracks cumulative streamflow impacts from new large withdrawals, while Iowa established additional requirements for its stressed Jordan Aquifer. These examples show how states can adapt their review and management approaches to address specific water-resource challenges.

Together, these lessons point to peer examples and available opportunities for Illinois to strengthen its high-capacity withdrawal evaluations, inform decisions with findings, and better implement the review process.

Looking ahead

Who makes water management decisions in Illinois? Join us for the final Shared Waters, Shared Future workshop, Understanding water supply governance and management in Illinois, on Thursday, November 12, 2026.

Missed this workshop? Find the recording and additional resources on the Shared Waters, Shared Future webpage.