Animal waste contains several potential water pollutants. It releases basic plant nutrients like phosphorus and nitrogen. Too much of these in surface waters can lead to algal blooms, oxygen depletion, and fish kills. Researchers have linked high nutrient levels with outbreaks of dangerous microbes, like Pfiesteria. Manure may also directly contribute fecal coliform bacteria and pathogens like Cryptosporidium.
Some manure also contains traces of hormones, heavy metals, or antibiotics.
Animal waste problems are not limited to water. Odors concern farm neighbors. Bulk manure storage can produce gases like ammonia and hydrogen sulfide at levels that may pose health risks for workers. In recent years, economic conditions have favored development of larger-scale animal operations 5 . Large operations have the potential to create large problems.