Generally, a facility where large numbers of farm animals are confined, fed, and raised, such as dairy and beef cattle feedlots, hog production facilities, and closed poultry houses. The EPA has developed a specific regulatory definition of CAFO for the purposes of enforcing the Clean Water Act (P.L. 92-500, 33 U.S.C. 1251-1387). The Act requires individual places that are potential sources of water pollution to obtain point source discharge permits that specify the allowable levels of effluent from each of these places. The regulations define animal feeding operations as those confining livestock or poultry for 45 days or more in a 12-month period in a facility that has no vegetative ground cover. Such places are further considered concentrated, and therefore required to have an EPA permit, if they exceed a size threshold or meet other criteria specified in the EPA regulations. The thresholds are 700 mature dairy cattle, 1,000 beef cattle, 125,000 chickens, 55,000 turkeys, 2,500 swine, or 10,000 sheep. In some regions, CAFO-size farms are called megafarms, confinements, or advanced farms.