A Practice Note discussing key environmental laws and regulations for upstream and midstream oil and gas operations. This Note addresses: regulation of oil and gas wastes under the Resource Conservation and Recovery Act (RCRA); air permitting requirements under the Clean Air Act (CAA); Underground Injection Control (UIC) Class II injection and disposal well permits; Clean Water Act (CWA) requirements including National Pollutant Discharge Elimination System (NPDES) permits, Section 404 permits, Section 401 certifications, and Spill Prevention, Control, and Countermeasure (SPCC) plans; environmental impacts review under the National Environmental Policy Act (NEPA); the Endangered Species Act (ESA) and Migratory Bird Treaty Act (MBTA); regulation of hydraulic fracturing; Naturally Occurring Radioactive Materials (NORM); and special environmental requirements for operations on federal lands.