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 956 community systems, which provide drinking water to people in their places of residence. Those community systems include 706 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 providing advice on water well construction. 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 with 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 been required to participate in federally-mandated efforts to reduce lead contamination in drinking water. Lead and copper are not typically present in the water when it leaves the treatment plant. Lead enters the water through contact with lead plumbing components, usually in individual homes. Copper levels are used as an indicator of how corrosive the water is—which determines how easily it will absorb lead from plumbing. If more than 10 percent of the homes in a community exceed the federal “action level” for lead—based on the results of a community-wide survey—the local water supply system must do additional testing and take steps to reduce lead levels. Monitoring Results for 1997 The following monitoring results were reported for calendar year 1997: Pesticides and Industrial Contaminants. During 1997, MDH conducted 66,178 tests for these contaminants. One municipal system tested slightly above the federal standard for tetrachloroethylene. There were no other violations of applicable health standards for these contaminants. Bacterial Contamination. Twenty-seven systems—including 20 municipal systems—tested positive for bacterial contamination in 1997. All but eight of the affected systems served fewer than 500 people. The largest served a population of slightly more than 1,000. All but five of the affected systems were able to resume normal operation within two weeks. Precautionary boil orders were issued for nine municipal systems and one nonmunicipal system during 1997, in connection with the spring flooding in northwestern and west central Minnesota—even though those systems did not actually test positive for coliform bacteria. Most of these systems were able to resume normal operations within a few days. Nitrate. Three municipal systems exceeded the nitrate standard in 1997, including a multi-county system in southwestern Minnesota. All three systems are exploring options for reducing nitrate levels in their water. Residents have been advised not to let infants consume the water until the problem can be corrected. Inorganic Chemicals and Radioactive Elements. During 1997, one nonmunicipal system tested slightly above the federal standard for arsenic. There were no other cases where current or proposed standards were exceeded for any of these contaminants. Lead and Copper. Minnesota’s community water supply systems are proceeding with efforts, begun during the early part of this decade, to reduce lead and copper levels in their drinking water. When these systems were first tested several years ago, 67 exceeded the action level for lead. Forty of those systems have since been retested, and no longer exceed the action level. Twenty-two of them were successfully retested during 1997. Of 142 systems that originally exceeded the action level for copper, 37 have since been resampled and found to be below the action level. Twenty-seven of these systems were successfully resampled in 1997. Major Developments During the Past Year Two events have had an especially significant impact on pact on Minnesota’s drinking water systems during the past year: Preparations for the issuance of “consumer confidence reports.” Under a new provision of the Safe Drinking Water Act, local water supply systems must begin issuing mandatory “consumer confidence reports” to their customers. Customers must be notified whenever contaminants are detected in their drinking water through routine testing. If contaminants exceed applicable drinking water standards, the notification must include information about the potential health effects of those contaminants. The new reporting requirement takes effect in 1999, and the first reports—covering calendar year 1998—must be issued by mid-year. Response to natural disasters. During the past year, a series of natural disasters has challenged the people of Minnesota. Widespread spring flood occurred during the spring of 1997 in west central and northwestern Minnesota. Tornados caused extensive damage in a number of south central Minnesota communities during the spring of 1998. These events had a profound impact on the affected communities. Given the circumstances, however, disruption of local water supply operations in these communities was relatively minimal. Although a number of precautionary boil orders were issued, most systems were able to resume normal operations within a few days. Even hard-hit communities like East Grand Forks were back on-line within a few weeks. This successful disaster response was at least partially a consequence of the careful planning and engineering decisions that have guided the development of Minnesota’s drinking water infrastructure. It is also a reflection of the effective working partnership that has been forged between the state’s local water supply systems and the public health community.
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