Mark Devries ... a documentary filmmaker who flew spy drones over North Carolina pig farms, claims to have captured video footage showing oceans of untreated animal waste ... oozing into the green Carolina countryside, in some cases close to residential areas. [Devries] shot the drone footage as part of a two-year investigation into the public-health consequences of waste management on farms operated by Smithfield Foods Inc. -- the largest pork producer in the country. Devries said he first became aware of the toxic cesspools" after speaking with neighbors who live near Smithfield facilities. "I was shocked," Devries said. "Pig manure is fairly similar to human waste, so it would be similar to having a pit of untreated human sewage the size of several football fields out in the open -- and in many cases, right in the vicinity of people's homes." A spokeswoman for Smithfield Foods said [that] state and federal regulators "sign off" on the company's treatment systems. The meat-packing giant is no stranger to criticism from environmentalists and animal-rights groups. Its "sea of waste" once earned it one of the largest fines ever from the Environmental Protection Agency, Rolling Stone reported in 2006. The project is likely to further spur the debate over "ag-gag" laws, which make it illegal to conduct undercover investigations at agricultural facilities. Although ag-gag is often framed as an animal-rights issue, such laws also meet with fierce opposition and legal challenges from free-speech advocates. "The issue that it brings up is a much broader issue of laws criminalizing information gathering by the press," Devries said.