section_path: Impact of pig husbandry/On the environment
section_name: On the environment
paragraph_text: On the environment
  
  As with the other forms of meat, producing pork is more energy-intensive than plant-based foods, and it is associated with more greenhouse gas emissions per calorie. However, emissions from pork are many times smaller than those of beef, veal and mutton, though larger than of chicken meat.
  
  Intensive pig production is also associated with water pollution concerns, as the swine waste is often stored above ground in so-called lagoons. These lagoons typically have high levels of nitrogen and phosphorus, and can contain toxic heavy metals like zinc and copper, microbial pathogens, or hold elevated concentrations of pharmaceuticals from subtherapeutic antibiotic use in swine. This wastewater from lagoons is liable to reach groundwater on farms, though there is little evidence for it reaching deeper into local drinking water supplies. However, lagoon spills, such as from heavy rains in the wake of a hurricane, can lead to fish kills and algal blooms in local rivers. In the United States, 35,000 mi (56,000 km) of river across over 20 states were estimated to have been contaminated by manure leakage as of 2015. There is also evidence that evaporation from lagoons can cause nitrogen and phosphorus to spread through the air as dry particles then reach other water basins when they fall out through dry deposition. This process then also contributes to water eutrophication.