Massive salt formations and their proximity to pipeline systems and power plants make Arizona attractive for natural gas storage. Caverns dissolved in subsurface salt are used to store LPG at Ferrellgas Partners LP facility near Holbrook and the AmeriGas Partners LP facility near Glendale. Three other companies are investigating the feasibility of storing natural gas in Arizona salt: Copper Eagle Gas Storage LLC, Desert Crossing Gas Storage and Transportation System LLC, and Aquila Inc. The most extensive salt deposits are in the Colorado Plateau Province. Marine and nonmarine salt deposits are present in Arizona.