The battle over developing vast, untapped oil sands deposits in the United States is heating up. Soon, the U.S. Bureau of Land Management will give private firms the opportunity to bid on the chance to dig up oil-soaked sandstone beneath 8.5 square kilometers of Asphalt Ridge, a sagebrush-speckled outcrop near the town of Vernal, Utah. If successful, the first oil sands lease on federal land will open a new frontier for U.S. energy firms, easing access to Utah formations believed to hold up to 19 billion barrels of oil. Environmental groups and conservation scientists, however, are opposing the move, arguing the Obama administration hasn't done enough to analyze the potential impacts on wildlife, air and water quality, and greenhouse gas emissions. The outcome of the battle could determine how far, and how fast, U.S. oil sands development proceeds.