Groundwater FAQs

Good to know: Facts about groundwater in Minnesota

  • More than 70% of Minnesotans rely on groundwater for drinking water.
  • As of 1990, an estimated 483,000 Minnesota residences used private wells to obtain water for their homes.
  • As of 1990, there were 2,388 active community public water supply wells in Minnesota.
  • In 1995, an estimated 700 million gallons of groundwater per day were withdrawn from Minnesota's aquifers (550 million gallons per day were permitted).
  • As of 1989, contaminated groundwater cost 17 Minnesota cities and 18 Minnesota companies a total of $67,072,000.
  • As of 1994, there were an estimated 700,000 to 1.175 million unsealed, abandoned wells in Minnesota that could potentially serve as contamination pathways to harm Minnesota groundwater.
  • As of May 1998, 100,000 unused wells have been sealed to protect Minnesota groundwater.


Although most Minnesota groundwater is naturally potable (suitable for human consumption), nature does produce groundwater with a chemical make up that is not potable in some areas. In addition, many human activities such as urban development, industrial processing, agriculture, chemical spills and even individual household septic systems have caused significant groundwater contamination in areas that previously had clean, potable groundwater.

Groundwater contamination can disperse over a wide area or migrate very deep underground. Often, many tons of overlying soil, sediment or rock hide the exact location of the contamination and present a substantial physical barrier to clean up efforts. As the groundwater moves, it often contaminates the earth materials it passes through which increases the volume of material that needs to be cleaned. The cost and technical difficulty of removing the contamination often multiplies over time as the contamination spreads out or migrates deeper.

Under favorable conditions, certain contaminants tend to degrade or clean up naturally in a reasonable amount of time in ground water. However, in other cases, contamination can persist for long times because groundwater typically moves very slowly and often lacks the range of purifying organisms and processes that tend to cleanse streams and lakes much quicker. As a matter of fact, some of Minnesota's groundwater entered the subsurface more than 30,000 years ago and is still slowly traveling deep underground.

  • The Groundwater Monitoring and Assessment Program (GWMAP) published reports (1991-2001) that summarize the results of statewide or regional groundwater monitoring programs. You can also review the water quality analyses for individual wells and see the data summarized on statewide maps.
  • The data presented in the statewide baseline groundwater monitoring report come from wells located throughout the state. However, since Minnesota is so large, it is unlikely you will find ground-water quality information from a well sampled by GWMAP at the exact location of your interest. Nonetheless, you may be able to estimate the quality of typical groundwater in your area by reviewing the analyses of water collected from the nearest wells in the same aquifer (or at a similar depth.) Please remember that the quality of groundwater at your specific location of interest may be very different than what is found in nearby wells.

In the majority of the cases, the MPCA uses the health risk limits (HRLs) set by the Minnesota Department of Health (MDH). These standards are available from the MDH by calling 651-215-0880 or 800-657-3908. However, individual MPCA regulatory programs may apply the HRLs differently depending on their program objectives or the situation. Contact the appropriate MPCA program for more specific information.

You can find out if there is a known tank leak, Superfund cleanup site, landfill or other potential source of groundwater contamination in your area by using search forms for the Minnesota Superfund Program or the Voluntary Investigation and Cleanup (VIC) Program. You can find additional information for programs that may have sites of environmental concern in your area on the Cleanup page.

If you want to contact a project manager, hydrogeologist, etc., for a particular clean-up site in the Twin Cities metro area, call Dianne Mitzuk at telephone 651-757-2573 for a referral. If you are concerned about a site outside of the Twin Cities metro area, we suggest that you call staff that do clean up work at one of our MPCA offices.    

For assistance with septic tanks or injection of other wastes from buildings (not cleaning up contamination), contact the appropriate MPCA district office and ask for the Individual Sewage Treatment System (ISTS) staff person. You may also call the MPCA ISTS information line at telephone 612-282-6246 or call 800-657-3864 and ask to be connected to the ISTS information line. For online information, please visit the Individual Sewage Treatment Systems page.

Based on where you believe the contamination originated, choose from the options listed below:

Please note: Some groundwater contamination issues may fall under the jurisdiction of both the MPCA and the Minnesota Department of Health (MDH).

For newer wells, look for a six-digit number that appears on an aluminum tag attached to the outside of the well casing. That number is called the Minnesota Unique Well Number. Then, call the Minnesota Department of Health at 651-215-0811 or 800- 383-9808 to find out who owns the well. A secondary option is to call your local county government office (try asking for the recorders office) and ask them to look for the well in the County Well Index database. Another option is to contact the Minnesota Geological Survey at 612-627-4784. You can also visit their web site for the County Well Index. If the above options prove ineffective, call the MPCA main switchboard at 651-296-6300 or 800-657-3864.

Contact the Minnesota Department of Health's Well Management Section at 651-201-4600 or (800) 383-9808. They can give you information on well specifications. They also have a rules handbook with specific guidelines about monitoring wells and borings.