Craig Barrow challenged an environmental permit allowing the City of Guyton to build and operate a wastewater land-application system near his farm and wetlands. An administrative law judge affirmed the permit, and the superior court entered judgment upholding the agency decision. The Georgia Court of Appeals held that the administrative decision rested on a plainly erroneous interpretation of Georgia’s antidegradation rule and the statutory requirement that a wastewater discharge comply with water-quality standards. The agency and the City offered an alternative factual theory about whether the spray-irrigation system would discharge harmful pollutants, but the administrative law judge had not decided the permit on that basis, so the appellate court would not affirm on an unruled ground. The court reversed the superior court’s judgment and remanded for proceedings consistent with the correct interpretation of the environmental law.