Groundwater: Background: Minnesota Department of Health


Clean and safe drinking water is an important part of a healthy environment and protecting public health. Many of us depend on groundwater as our primary source for drinking water - whether we use a private well, public water supply, or some other groundwater source. The quality of most drinking water in Minnesota is good; however, it is possible for well water to be contaminated by bacteria, nitrate, arsenic or other chemicals. It is important to know the source of your water and whether it needs to be tested.

The Minnesota Department of Health (MDH) works closely with the U.S. Environmental Protection Agency and other agencies to protect Minnesota's groundwater that is used for drinking. The following provides background information about groundwater protection and monitoring activities in Minnesota. For more information, see groundwater-related Programs/Services.

On this page:
Minnesota Groundwater (used for drinking)
Protecting Groundwater
Monitoring Groundwater

Also, see: Minnesota Groundwater Information Guide

Minnesota Groundwater (used for drinking)

The U.S. Geological Survey reports that during 1995, about 79 percent of all Minnesotans obtained their domestic water supplies from groundwater and nearly 750 million gallons of groundwater were withdrawn every day. Groundwater sources of drinking water may be private (private wells that serve individual homes) or public (serving larger numbers of individuals).

Safe Drinking Water

The homeowner is responsible for the safety of the drinking water from a private well. Properly constructed and maintained water wells can provide many years of trouble-free service, but wells will eventually deteriorate or become damaged, and allow surface contaminants to enter the water. The Minnesota Department of Health (MDH) has helpful information for homeowners about assuring that water from private wells is safe and that wells are properly sealed to protect ground water resources. For more, see Water Quality/Well Testing/Well Disinfection.

Public water systems are regulated by MDH and are classified as either community or noncommunity systems. Community public water systems, such as municipalities and manufactured home parks, serve consumers in a residential setting. Noncommunity public water systems are facilities such as schools, factories, restaurants, resorts, and churches that are served by their own supply of water (usually a well). Currently, there are almost 1,000 community water supply systems and over 7,000 noncommunity public water systems in Minnesota.

The MDH’s Drinking Water Protection Section ensures that the state’s public water systems meet federal and state guidelines for safe drinking water. Section staff monitor drinking water quality, perform on-site inspections of public water systems, and review plans for water system construction. For more information, read the descriptions below or see Drinking Water Protection.

Sanitary Surveys

A sanitary survey is an on-site review of the adequacy of the water source, facilities, equipment, operation and maintenance of a public water system for producing and distributing safe drinking water. Sanitary surveys of public water systems are conducted by MDH at a frequency of once every 18 months for community public water systems and once every three years for noncommunity public water systems.

Testing for Contaminants

Water from public water systems is required to be sampled and analyzed for a variety of contaminants. The number of contaminants that must be tested depends on the type of public water system. Community water systems are tested for contaminants such as bacteria, nitrate, pesticides, solvents, and metals. All noncommunity water systems are tested at least annually for the total coliform bacteria and nitrate. Noncommunity water systems that serve the same people every day (such as schools and factories) are also tested for contaminants such as pesticides, solvents, and metals. The Minnesota Department of Health keeps detailed information on testing requirements and test results.

Evaluating Health Risks

The health risks from drinking water contaminants are evaluated by the U.S. Environmental Protection Agency and by the Minnesota Department of Health. Each agency makes public the health effects of the contaminants that have been found in groundwater. Each agency also makes public the concentrations or levels of concern for more than 100 contaminants. These levels of concern are based on protecting human health and, in the case of the U.S. EPA, also take into account the feasibility of controlling contamination in drinking water. MDH health-based guidance for water takes the form of Health Risk Limits (HRLs), Health-Based Values (HBVs), and Risk Assessment Advice (RAA).

Identifying Emerging Threats

MDH's Health Risk Assessment Unit and Site Assessment and Consultation Unit identify and investigate chemicals that may not be present in Minnesota groundwater, but are released to the environment (e.g., to soil or to surface water) and have the potential to be transported to groundwater. Under the Drinking Water Contaminants of Emerging Concern (CEC) program, MDH staff identify chemicals of emerging concern for evaluation and develop health-based guidance values for these chemicals when sufficient data are available.

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Protecting Groundwater

Programs in state and local government agencies are responsible for protecting groundwater from contamination so that drinking water supplies from water are safe for human consumption. The Minnesota Department of Health has many roles in this effort including protecting water, ensuring that drinking water from wells is tested and is safe, and recommending cleanup of contaminated sites. Other state agencies also have diverse and important roles in ensuring that the drinking water from wells is safe for human consumption.

Protecting Sources of Groundwater

The Source Water Protection Unit in the Drinking Water Protection Section focuses on the protection of public drinking water sources, including groundwater wells. The Unit has created a Source Water Assessment for each of the state’s public water systems, which describes the water sources used and their susceptibility to contamination. The Unit also helps public water systems in developing their Wellhead Protection Plans, which include strategies to prevent the pollution of the groundwater. For more information, see Source Water Protection.

Properly Constructed and Sealed Wells

The Well Management Section is responsible for developing and enforcing well drilling rules to prevent the spread of groundwater contamination. The Section is also responsible for a program for assuring that unused wells are properly sealed by licensed well contractors. The Section also determines the location of "Special Well Construction Areas." These are areas where extra care in drilling is needed because groundwater contamination has, or may, result in risks to the public health.

Reporting Spills and Contamination

The State of Minnesota maintains a 24-hour emergency number (Dept. of Public Safety Duty Officer) to report oil or chemical spills and other environmental emergencies. The number is 651-649-5451 or 800-422-0798.

Information may be forwarded to the Minnesota Pollution Control Agency for cleanup of contaminated sites (such as fertilizer or fuel) that can affect surface and groundwater. For example, the MPCA Underground Storage Tank (UST) Program was created to help prevent contamination caused by leaking tanks.

Contamination incidents related to agriculture also may be investigated and cleaned up by the Minnesota Department of Agriculture.

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Monitoring Groundwater

Monitoring Quantity

The U.S. Geological Survey (USGS) is the leading Federal agency in Minnesota that collects and interprets water-resource data and information used by resource managers, planners, and the general public. To define the availability of water for public, irrigation, and industrial supplies, the USGS monitors stream flow, lake levels, and ground-water levels at many locations and has studied numerous aquifers in Minnesota. Typically, the studies describe the effects of present and future groundwater withdrawals on the levels and quality of groundwater and streams. The results of USGS water-quality studies provide water managers with essential information needed to make ground-water management decisions throughout Minnesota. For more, see U.S. Geological Survey.

Monitoring Quality

Three Minnesota State Agencies — the Departments of Agriculture and Health and the Minnesota Pollution Control Agency — have developed a joint plan for conducting ground water quality monitoring on a statewide basis in Minnesota. The joint plan recognizes the Agencies' differing purposes, goals and roles in ground water quality monitoring based on their respective state and federal requirements, while setting forth a monitoring system that will be conducted in an integrated fashion. Commissioners of the three agencies signed the monitoring agreement on February 18, 2004.

The Minnesota Pollution Control Agency established a Ground Water Monitoring and Assessment Program (GWMAP), which resulted in a set of baseline data on groundwater quality throughout Minnesota based on sampling conducted from 1990 to 1996. Since then, studies of trends of contamination have been conducted (1996-2000). Funding for GWMAP was discontinued in 2001.

The MDA periodically collects and analyzes water samples from selected locations throughout the state to determine the identity, concentration, and frequency of detections of pesticides in Minnesota's ground and surface water resources. Water monitoring programs of the MDA are designed to define long-term impacts of normal pesticide use on waters within the state. The monitoring focuses on specific groundwater sources (aquifers) beneath the central sand plain region as being particularly vulnerable in the state and twelve counties in this area are currently being monitored (see Monitoring and Assessment of Agricultural Chemicals). More recently, the MDA has extended the regional monitoring program to other areas of the state. In addition, the MDA began sampling 100 drinking water wells across the state (statewide ambient drinking water evaluation program). These expanded monitoring programs are in the February 18, 2004 water quality monitoring agreement.

The Minnesota Department of Health also produces reports on routine testing done on public water supplies.

The current agreement between the three agencies further describes the different roles of the agencies, the authority each agency has to conduct groundwater quality monitoring, and ways in which agencies share information.

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Updated Wednesday, 17-Nov-2021 14:37:38 CST