Safeguarding a Precious Resource A Summary of Drinking Water Protection Activities in Minnesota—1998

The Minnesota Department of Health (MDH) is responsible for enforcing the federal Safe Drinking Water Act—and safeguarding the quality of drinking water—in our state. That includes responsibility for regulating 8,900 public water supply systems statewide. That figure includes 958 community systems, which provide drinking water to people in their places of residence. Those community systems include 708 municipal systems, serving towns or cities. The Major Elements of Drinking Water Protection Minnesota's drinking water protection strategy includes three major elements: · Prevention measures are used to protect the quality of drinking water at the source—by controlling potential sources of pollution, regulating land use, and reviewing plans and providing advice on construction of water treatment and distribution facilities, and inspecting these facilities on a regular basis. · Treatment measures—including routine disinfection—are used to make the water palatable and safe to drink. · Monitoring of water supplies for potentially harmful contaminants—on a routine basis—is the critical element of the state's enforcement responsibilities under the Safe Drinking Water Act. The Monitoring Process Minnesota's community water supply systems are monitored for the following types of contaminants: · Pesticides and industrial contaminants. Each system may be tested regularly for up to 118 pesticides and industrial contaminants—including both synthetic organic chemicals (SOCs) and volatile organic chemicals (VOCs). The list of chemicals to be tested for—and the testing schedule—may vary from one system to another. Testing requirements depend on factors like whether a particular chemical is likely to be present in the local environment—and how vulnerable the system is to contamination. If a system exceeds the applicable federal or state drinking water standard for a particular chemical, it must notify the people who use the water and take appropriate steps to correct the problem. · Bacterial contamination. Larger community systems are tested monthly—and smaller systems are tested quarterly—for contamination by coliform bacteria. The coliform test is used as a general indicator of water quality in the system, in terms of potential microbial contamination. Whenever bacterial contamination is detected, people served by the system are advised to boil the water before using it for drinking or cooking. The system must be disinfected, flushed, and found to be free of contamination before the boil order can be lifted. · Nitrate. Each system must be tested annually for nitrate. Nitrate occurs naturally in the environment, but elevated nitrate levels in drinking water are usually associated with the use of fertilizer, or the breakdown of human and animal waste. It is a health concern primarily for infants under the age of six months. If the federal standard for nitrate is exceeded, an advisory is issued regarding consumption of the water by infants. The advisory remains in effect until steps can be taken to correct the nitrate problem. · Inorganic Chemicals and Radioactive Elements. Each system is typically tested once every three years—or as often as once a year, in some cases—for a list of 13 additional inorganic chemicals, and a number of radioactive elements. Both inorganic chemicals and radioactive elements may be naturally present in the water. If the water exceeds health standards for either type of contaminant, people who use the water are informed, and steps are taken to correct the problem. · Lead and Copper. For the last several years, community water supply systems have participated in efforts to reduce lead and copper contamination in drinking water. Lead and copper are not typically present in the water when it leaves the treatment plant. Lead and copper differ from other contaminants in that they are rarely present in source waters. Rather, they enter the water through contact with plumbing components, usually in individual homes. If more than 10 percent of the homes in a community exceed the federal "action level" for lead or copper based on the results of community-wide monitoring—the local water supply system must do additional testing and take steps to reduce levels. Systems that exceed the action level for lead must also perform a regular program of public education.
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Minnesota Department of Health (St. Paul, Minnesota)
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Minnesota Water Research Digital Library
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Creative Commons