RALEIGH, N.C. (AP) — Several hog farms in North Carolina were properly allowed to collect energy from the animals’ waste, a state appeals court said Tuesday, ruling that their permit applications were scrutinized appropriately before their approval.

A three-judge panel on the Court of Appeals ruled unanimously in favor of the state Department of Environmental Quality and for Murphy-Brown LLC, which sought the permits for four farms they own and operate in Duplin and Sampson counties. Murphy-Brown wanted to construct anaerobic waste digestion systems that would cover portions of open-air lagoons containing waste, which would let them capture methane and other biogas.

Two environmental groups had challenged the approved permits, arguing that state law requires stricter pollution limits.

The groups, Environmental Justice Community Action Network and Cape Fear River Watch, said the permits would lead to more pollution and harm water that their members rely on. They told the appeals judges that DEQ failed to consider some environmental standards set in state law. One that they cited declares “all permit decisions shall require that the practicable waste treatment and disposal alternative with the least adverse impact on the environment be utilized.”

The groups unsuccessfully appealed DEQ’s authorizations in 2021 for the waste management systems to both an administrative law judge and a Superior Court judge.

Writing for the panel, Judge Jefferson Griffin said that DEQ wasn’t required to consider the standards described by the permit opponents to the proposed animal waste management systems. State law provides a less burdensome regulatory process, combined with its own requirements for best management practices and performance standards, for these operations, he wrote.

The ruling is tempered because DEQ later granted general permits for three of the four farms that supersede the previous permits and that still allowed anaerobic digesters to be constructed. The environmental groups have filed separate, pending challenges to those new permits, the opinion said.

A state law that took effect in October also attempts to clarify that animal waste management systems must obtain a permit process that is distinct from the process for permits for other sources of water pollution, according to the opinion.