MountainWest Pipelines Holding Company, through its subsidiaries, engages in the business of transporting and storing natural gas. Dominion Energy Quester Pipeline, LLC, a wholly owned subsidiary, and its subsidiaries and certain associated affiliates, including Overthrust Pipeline and White River Hub, operate 2,160-miles of highly contracted, FERC-regulated interstate natural gas pipelines providing transportation and underground storage services in Utah, Wyoming and Colorado.