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2008 Drinking Water ReportCity of Shorewood 2008 Drinking Water Report The City of Shorewood is issuing the results of monitoring done on its drinking water for the period from January 1 to December 31, 2008. The purpose of this report is to advance consumers' understanding of drinking water and heighten awareness of the need to protect precious water resources. Source of Water The City of Shorewood provides drinking water to its residents from the following groundwater sources: • Six wells ranging from 326 to 640 feet deep, that draw water from the Prairie Du Chien-Jordan, Prairie Du Chien Group, and Franconia-Ironton-Galesville aquifers. • Purchases treated water from the City of Chanhassen which obtains its water from wells in the Prairie Du Chien-Jordan, Quaternary Buried Unconfined, and Multiple aquifers. The water provided to customers may meet drinking water standards, but the Minnesota Department of Health has also made a determination as to how vulnerable the source of water may be to fixture contamination incidents. If you wish to obtain the entire source water assessment regarding your drinking water, please call 651-201-4670 or 1-800-818-9318 (and press 5) during normal business hours. Also, you can view it on line at www.health.state.mn.us/divs/eh/water/swp/swa. Call (952) 474-3236 if you have questions about the City of Shorewood drinking water or would like information about opportunities for public participation in decisions that may affect the quality of the water. Results of Monitoring No contaminants were detected at levels that violated federal drinking water standards. However, some contaminants were detected in trace amounts that were below legal limits. The table that follows shows the contaminants that were detected in trace amounts last year. (Some contaminants are sampled less frequently than once a year; as a result, not all contaminants were sampled for in 2008. If any of these contaminants were detected the last time they were sampled for, they are included in the table along with the date that the detection occurred.) Key to abbreviations: MCLG - Maximum Contaminant Level Goal: The level of a contaminant in drinking water below which there is no known or expected risk to health. MCLGs allow for a margin of safety. MCL - Maximum Contaminant Level: The highest level of a contaminant that is allowed in drinking water. MCLs are set as close to the MCLGs as feasible using the best available treatment technology. MRDL - Maximum Residual Disinfectant Level. MRDLG - Maximum Residual Disinfectant Level Goal. AL- Action Level: The concentration of a contaminant which, if exceeded, triggers treatment or other requirement which a water system must follow. 90th Percentile Level - This is the value obtained after disregarding 10 percent of the samples taken that had the highest levels. (For example, in a situation in which 10 samples were taken, the 90th percentile level is determined by disregarding the highest result, which represents 10 percent of the samples.) Note: Contaminant MCLG MCL Level Found Typical Source of Contaminant (units) Range Average (2008) /Result* Alpha Emitters 0 15.4 N/A 9.5 Erosion of natural deposits. (pCi/1) (12/18/2006) Arsenic (ppb) 0 10 N/A 5.53 Erosion of natural deposits; Runoff from (02/16/2005) orchards; Runoff from glass and electronics production wastes. Barium (ppm) 2 2 N/A .11 Discharge of drilling wastes; Discharge (02/16/2005) from metal refineries; Erosion of natural deposits. Combined 0 5.4 N/A 5.3 Erosion of natural deposits. Radium (pCi/1) (12/18/2006) Fluoride (ppm) 4 4 .43-1.5 1.21 State of Minnesota requires all municipal water systems to add fluoride to the drinking water to promote strong teeth; Erosion of natural deposits; Discharge from fertilizer and aluminum factories. Haloacetic Acids 0 60 N/A 3.1 By-product of drinking water (HAA5)(ppb) disinfection. TTHM (Total 0 80 N/A 3.4 By-product of drinking water trihalomethanes) disinfection. (ppb) While your drinking water meets EPA's standard for arsenic, it does contain low levels of arsenic. EPA's standard balances the current understanding of arsenic's possible health effects against the costs of removing arsenic from drinking water. EPA continues to research the health effects of low levels of arsenic, which is a mineral known to cause cancer in humans at high concentrations and is linked to other health effects such as skin damage and circulatory problems. Contaminant (units) Level Found Typical Source of Contaminant Range Average/ (2008) Result* Radon (pCi/1) (10/03/2005) N/A 927 Erosion of natural deposits. *This is the value used to determine compliance with federal standards. It sometimes is the highest value detected and sometimes is an average of all the detected values. If it is an average, it may contain sampling results from the previous year. Radon is a radioactive gas which is naturally occurring in some groundwater. It poses a lung cancer risk when gas is released from water into air (as occurs during showering, bathing, or washing dishes or clothes) and a stomach cancer risk when it is ingested. Because radon in indoor air poses a much greater health risk than radon in drinking water, an Alternative Maximum Contaminant Level (AMCL) of 4,000 picoCuries per liter may apply in states that have adopted an Indoor Air Program, which compels citizens, homeowners, schools, and communities to reduce the radon threat from indoor air. For states without such a program, the Maximum Contaminant Level (MCL) of 300 pCi/1 may apply. Minnesota plans to adopt an Indoor Air Program once the Radon Rule is finalized. Contaminant (units) MRDLG MRDL xxxY xxxxY Typical Source of Contaminant Chlorine (ppm) 4 .8-2.4 1.17 Water additive used to control microbes. ****Highest and Lowest Monthly Average. * * * * *Highest Quarterly Average. Contaminant 90% #sites (units) MCLG AL Level over AL Typical Source of Contaminant Copper (ppm) N/A 1.3 .92 0 out Corrosion of household plumbing of 20 systems; Erosion of natural deposits. Lead (ppb) N/A 15 10 1 out Corrosion of household plumbing of 20 systems; Erosion of natural deposits. If present, infants and children who drink water containing lead in excess of the action level could experience delays in their physical or mental development. Children could show slight deficits in attention span and learning abilities. Adults who drink this water over many years could develop kidney problems or high blood pressure. Lead in drinking water is primarily from materials and components associated with service lines and home plumbing. City of Shorewood is responsible for providing high quality drinking water, but cannot control the variety of materials used in plumbing components. When your water has been sitting for several hours, you can minimize the potential for lead exposure by flushing your tap for 30 seconds to 2 minutes before using water for drinking or cooking. If you are concerned about lead in your water, you may wish to have your water tested. Information on lead in drinking water, testing methods, and steps you can take to minimize exposure is available from the Safe Drinking Water Hotline or at littp://www.epa.gov/safewater/lead. Some contaminants do not have a Maximum Contaminant Levels established for them. These unregulated contaminants are assessed using state standards known as health risk limits to determine if they pose a threat to human health. If unacceptable levels of an unregulated contaminant are found, the response is the same as if an MCL has been exceeded; the water system must inform its customers and take other corrective actions. In the table that follows are the unregulated contaminates that were detected: Contaminant (units) Level Found Typical Source of Contaminant Range Average (2008) /Result Sodium (ppm) 5.5-21 21 Erosion of natural deposits. Sulfate (ppm) nd-23.2 23.2 Erosion of natural deposits. Compliance wilt ill National Primary Drinking Water Regulations The sources of drinking water (both tap water and bottled water) include rivers, lakes, streams, ponds, reservoirs, springs, and wells. As water travels over the surface of the land or through the ground, it dissolves naturally-occurring minerals and, in some cases, radioactive material, and can pick up substances resulting from the presence of animals or from human activity. Contaminants that may be present in source water include: Microbial contaminants, such as viruses and bacteria, which may come from sewage treatment plants, septic systems, agricultural livestock operations, and wildlife. Inorganic contaminants, such as salts and metals, which can be naturally-occurring or result from urban stormwater runoff, industrial or domestic wastewater discharges, oil and gas production, mining, or farming. Pesticides and herbicides, which may come from a variety of sources such as agriculture, urban stormwater runoff, and residential uses. Organic chemical contaminants, including synthetic and volatile organic chemicals, which are by- products of industrial processes and petroleum production, and can also come from gas stations, urban stormwater runoff, and septic systems. Radioactive contaminants, which can be naturally-occurring or be the result of oil and gas production and mining activities. In order to ensure that tap water is safe to drink, the U.S. Environmental Protection Agency (EPA) prescribes regulations which limit the amount of certain contaminants in water provided by public water systems. Food and Drug Administration regulations establish limits for contaminants in bottled water which must provide the same protection for public health. Drinking water, including bottled water, may reasonably be expected to contain as least small amounts of some contaminants. The presence of contaminants does not necessarily indicate that water poses a health risk. More information about contaminants and potential health effects can be obtained by calling the Environmental Protection Agency's Safe Drinking Water Hotline at 1-800-426-4791. Some people may be more vulnerable to contaminants in drinking water than the general population. Immuno-compromised persons such as persons with cancer undergoing chemotherapy, persons who have undergone organ transplants, people with HITS/AIDS or other immune system disorders, some elderly, and infants can be particularly at risk from infections. These people should seek advice about drinking water from their health care providers. EPAICDC guidelines on appropriate means to lessen the risk of infection by Cryptosporidium are available from the Safe Drinking Water Hotline at 1-800-426-4791.