Although their market volumes have been much less than in other regions, refineries in the Rocky Mountains have generally sold fuel at the lowest prices in the US due to their lower feedstock costs. If Canadian heavy oil continues to be priced at an attractive discount, refineries are expected to continue to take large volumes despite the light crude oil surplus in the region. PADD 5 (West Coast of the United States) is a large potential market for increasing Canadian oil sands output as production of oil from its historic sources in Alaska and California has declined steeply in recent decades, and it has no pipeline access to new US production in North Dakota or Texas. Imports from countries outside North America have been increasing in volume although most of it is significantly more expensive than Canadian or domestic American oil. Many of the refineries in California and Washington State are capable of processing heavy oil because much of the oil production in California is heavy, as is much imported oil. They have also noted that a mix of 55% North Dakota Bakken oil and 45% Western Canadian Select is a reasonable substitute for badly diminished supplies of Alaska North Slope oil. PADD V is physically disconnected from the pipeline systems of the rest of the United States, but the Trans Mountain Pipeline delivers oil of all types from Alberta across British Columbia to refineries in Washington, which in 2012 processed of imported oil, 60% of which came from Canada. If the Trans Mountain Expansion and Northern Gateway pipelines are completed, total capacity from Western Canada to the West Coast could exceed by 2018. California has no pipeline connections that could deliver oil from other producing states or Canada, and in 2012 imported of oil, only 5% of which came from Canada and two-thirds from Saudi Arabia. Canadian (and North Dakota) oil has been much cheaper than Arabian oil so potential exists for delivering oil sands production to California from the West Coasts of British Columbia and Washington by tanker. However, a big question mark hanging over the California refining market is the California Low Carbon Fuel Standard.