Twenty-eight members of Congress signed a letter on Dec. 3 urging Secretary of State Hillary Clinton and the State Department to request a new Environmental Impact Study on the Keystone XL pipeline that would carry tar sands oil from Canada to Texas. The lawmakers note in the letter that the Environmental Protection Agency gave the current EIS its lowest possible rating. "Not only does tar sands oil have a higher life-cycle for greenhouse gas emissions, but it also has an environmentally destructive extraction process and environmentally precarious transportation system," the members write. The pipeline has been intently scrutinized in Nebraska, where it would run through the Sandhills and over the Ogallala Aquifer, the state's largest source of drinking and irrigation water. None of Nebraska's three Congress members signed the letter.