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Water Withdrawal Assessment Tool

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Environment, Great Lakes, and Energy

Water Withdrawal Assessment Tool

Water Withdrawal Assessment Tool (WWAT)

Required if you're installing any new or increased large quantity water withdrawals.

To sign into MiLogin to continue to the WWAT.

The Water Withdrawal Assessment Tool (WWAT) is part of Michigan’s fulfillment of the Great Lakes Compact obligations to conserve and manage our water resources. 

  • Michigan law prohibits water withdrawals from causing excessive depletion of stream and river flows, called an Adverse Resource Impact (ARI).
  • The Water Withdrawal Assessment Tool estimates the potential impact a water withdrawal may have on nearby streams and rivers relative to the ARI limit.
  • Landowners planning a new or increased withdrawal using one or more pumps capable of at least 70 gallons per minute must obtain approval from EGLE prior to operation. 
  • Use of the Water Withdrawal Assessment Tool is required for approval of wells or intakes directly from a stream, river, or pond less than 5 acres.
  • Withdrawal approval is attained by a determination of no ARI. 
  • Approved withdrawals receive an EGLE Water Withdrawal Registration. 
  • Withdrawals must be operational within 18 months after approval or the Registration becomes void.

The WWAT is the central component of the Water Withdrawal Assessment Process -- the means by which Michigan regulates large quantity withdrawals in the management of our water resources.

Modernized Water Withdrawal Assessment Tool: Enhancing Efficiency and Transparency in Michigan Water Use

Python Decision Support System Tool for estimating High Capacity Well Responses: pycap-dss. version 1.0

Technical resources

Additional in-depth information about the Water Withdrawal Assessment Tool is available in the following technical documents.

Michigan’s Water Withdrawal Assessment Process and Internet Screening Tool

Michigan Department of Natural Resources (DNR)
Fisheries Division

May 2011

Regression Model for Computing Index Flows

U. S. Geological Survey (USGS)

2008

Groundwater Withdrawal Component of the Water Withdrawal Assessment Tool

U. S. Geological Survey (USGS)
Michigan Department of Natural Resources (DNR)

2009

About the water withdrawal assessment process

We review how a proposed large water withdrawal could affect nearby streams and rivers.

A large quantity withdrawal means taking 100,000 gallons or more of water per day (averaged over 30 days) for a shared water system. For a groundwater LQW, that means that the well is completed, pump installed and connected to a power source. For a surface water LQW, that means that the pump is installed and connected to a power source.

This review is science-based and updated as new data become available. It looks at:

  • how groundwater withdrawals affect stream flow,
  • how stream flow affects fish populations, and
  • whether the withdrawal could seriously harm a stream or river.

The review also provides guidance on how to reduce potential impacts.

Get an in-depth explanation of the process