tailieunhanh - TROUBLED WATERS: Farm Pollution threatens Drinking Water

Chlorine and other chemicals used to disinfect source water can form carcinogenic compounds when they react with organic matter. These compounds become a serious problem when nutrient overloads trigger recur- rent and persistent blooms of algae that contaminate source water. The reaction between chlorine and algal organic matter generates trihalomethanes and haloacetic acids, two types of disinfection byproducts that are federally regulated, as well as many other types of toxic byproducts. A study sponsored by the . EPA and the Water Research Foundation found that algal blooms also lead to formation of highly carcinogenic nitrog- enous disinfection byproducts, which are not currently. | TROUBLED WATERS FARM POLLUTION THREATENS DRINKIN I w by Olga V. Naidenko Senior Scientist Craig Cox Senior Vice President for Agriculture and Natural Resources Nils Bruzelius Executive Editor America s pure drinking water is at risk from poor farming practices that contaminate streams lakes and groundwater with fertilizer and manure. ENVIRONMENTAL WORKING GROUP http report troubledwaters 1436 U Street. NW Suite 100 Washington DC 20009 Table of Contents Troubled Waters Farm Pollution Threatens Drinking Water Executive Careless Farming Takes a Toll on Drinking Water .7 In Most Agricultural Watersheds Farm Runoff Causes the Bulk of Water Quality Source Water Overloaded with Nutrients Threatens Tap Nitrate .10 Disinfection Cyanobacteria and Cyanotoxins .10 The Health Risks - Why It Nitrate - Deadly for Infants Dangerous for Adults .11 Disinfection Byproducts - Cancer Asthma and Cyanobacteria and Cyanotoxins - No Legal Nutrient Overload is Nutrient Pollution in Streams .14 Nutrient Pollution in Lakes .15 Nitrogen Pollution in Groundwater .17 Agricultural Contaminants in Source Water and Tap Nitrate in Tap Domestic Wells are Especially Vulnerable .22 Disinfection Byproducts - Making a Bad Situation Worse .25 Disinfection Byproducts are Too Often Found in Tap Cyanobacterial Blooms are a Worsening Cyanobacteria in Iowa National Lake Survey Findings of Cyanobacteria in Illinois Minnesota and Wisconsin ENVIRONMENTAL WORKING GROUP April 2012 2 Cyanobacteria in Illinois Lakes .34 Cyanobacteria in Minnesota Cyanobacteria in Wisconsin The High Cost of Cleaning Up Source Iowa Water Utility Survey Treating Source Water Contaminated with Agricultural Chemicals .36 Case Studies .38 Nitrate The Cost of Cyanotoxins .41 Conclusion .43 Source Water and the Farm

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