http://www.drmcdougall.com/misc/2006nl/dec/truth.htm

In the United States livestock is responsible for 55 percent of the erosion and sediment, 37 percent of the pesticide use, 50 percent of the antibiotic use, and a third of the load of nitrogen and phosphorus put into freshwater sources.

Widespread overgrazing disturbs water cycles, reducing replenishment of above and below ground water resources. Significant amounts of water are withdrawn for the production of feed.

Livestock’s very presence in vast tracts of land and its demand for feed crops also contribute to loss of other plants and animals; livestock is identified as a culprit in 15 out of 24 important ecosystems that are assessed as in decline. The loss of species is estimated to be running 50 to 500 times higher than background rates found in the fossil record.