A recent Sierra Club posting, "E. coli. It's what's for dinner?" has an excellent article on factory farming. http://www.sierraclub.org/factoryfarms/

This brings us back to the topic of how E. coli has gotten into our spinach, lettuce and who knows what will be next. This is a problem of a contaminated irrigation water and much more. The lawsuits should not be directed at the produce farmer but at the source of the uncontrolled contaminated water. Our drinking water, rivers and lakes are at risk for contamination from animal waste. Concentrated Animal Feeding Operations (CAFO) produce huge amounts of animal waste that is leaking into our water supply. The statistics are staggering; hog, cattle and chicken waste has polluted 35,000 miles of rivers in 22 states and contaminated groundwater in 17 states (source: Sierra Club). This cannot continue unchecked. These CAFOs must control their waste and be accountable. Visit the Sierra Club website to find out what you can do about this. http://www.sierraclub.org