County Well Index

The County Well Index (or CWI) is a database that contains subsurface information for over 533,000 water wells drilled in Minnesota.

The data are derived from well contractors' logs of geologic materials encountered during drilling, and later interpreted by geologists at the MGS. Available data also include casing, screen and pump information. Confirmed locations and interpreted geologic well records are available for over 340,000 of the water wells.

The CWI database is maintained by the MGS in partnership with the Minnesota Department of Health (MDH), and can be accessed online through the Minnesota Well Index (MWI) application provided below.


To learn more about CWI and the database structure, please see the Database Dictionary. If a CD or downloadable file is required, please contact the MGS Map Sales Office.

CWI Data Procedures Manual

The County Well Index (CWI) Data Procedures Manual (PDF) was developed to describe data management requirements for Minnesota Unique Well Numbers (Unique Numbers) and associated well location data housed in the County Well Index (CWI) database.

These procedures were developed by the following state agencies, in partnership with MGS:

  • MN Department of Health (MDH)
  • MN Department of Natural Resources (DNR)
  • MN Pollution Control Agency (MPCA)
  • MN Department of Agriculture (MDA)

Special thanks to Nila Hines, Todd Petersen and Linse Lahti at Minnesota Department of Natural Resources for report management, compilation and editing.

Frequently asked questions

For questions regarding the CWI database, please refer to the CWI FAQs page. This does not include information about the web-based CWI or MWI application. For help pertaining to those, please refer to the Minnesota Well Index (MWI) page in the Related Links section.


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