Williams Partners L.P. is an energy infrastructure company. The Company has operations across the natural gas value chain from gathering, processing, and interstate transportation of natural gas and natural gas liquids to petchem production of ethylene, propylene, and other olefins. It operates through its Northeast G&P, Atlantic-Gulf, West, and Natural gas liquid (NGL) & Petchem Services segments. Under the Northeast G&P segment, it owns and operates fractionation facilities at Moundsville, de-ethanization and condensate facilities at its Oak Grove processing plant. The Atlantic Gulf segment includes the Company's interstate natural gas pipeline, Transcontinental Gas Pipe Line Company, LLC. The West segment includes its interstate natural gas pipeline, Northwest Pipeline, and natural gas gathering processing and treating operations. The NGL & Petchem Services segment included the Company's 88.5% interest in an olefins production facility in Geismar, Louisiana as of December 31, 2016.