Environmental Damage
You may be wondering how a farm can damage the environment. The answer is simple: manure. According to StopFactoryFarms.org,
The EPA has estimated that all confined animals generate 3 times more raw waste than is generated by humans in the U.S.
All this waste produced by the animals has to end up somewhere but where? On a typical farm it would be used as manure, but on a factory farm there is far too much of it to do that, so it is stored in a "lagoon," then sprayed over the surrounding lands without being sanitized first. The lagoons the manure is stored in are sealed to prevent leakage into the groundwater, but leakage still occurs. During storms, there can also be overflow into lakes and rivers nearby, contaminating everything.
The EPA has also estimated that 20% of all man-made methane production is a result of the livestock on factory farms. Animals are fed low quality food that they are unable to digest, which contributes to high methane emissions. The breaking down of organic compounds in manure contributes to air pollution as well.