If the proposal makes it through the approval process to President Obama's desk, says Tony Iallonardo, a spokesman for the National Wildlife Federation, Obama "really needs to deny the permit—from a financial basis. The costs from Hurricane Sandy are too high to continue to approve pipelines like this." While environmental groups, including NWF, say they may go to court if a final decision favors the pipeline, a presidential permit, unlike a decision from a federal agency, is not subject to judicial review.

Some opponents of Keystone fear that corrosive Canadian oil sands will weaken the pipeline and make spills more likely. However, a recent report from the U.S. Pipeline and Hazardous Materials Safety Administration on the July 1, 2011, rupture of an ExxonMobil pipeline in the Yellowstone River shows that the rupture was caused by external scouring and debris from record-high floods on the river and debris, not interior damage. The steel pipe, which occasionally carries oil sands from Alberta, showed only evidence of normal interior pitting.

The report, by the engineering firm of Kiefner & Associates Inc. of Worthington, Ohio, concluded that was no evidence that "internal or external corrosion, stress-corrosion cracking, pipe manufacturing defects or mechanical damage developed in service and contributed to the failure." The 12-in. pipe was installed in 1991 using an open trench method and buried 6 to 8 ft below the river bed. Subsequent flooding eroded the pipe's covering. Since the spill, the pipe has been reinstalled using horizontal drilling deep below the river, according to the report.

The report concludes that if ExxonMobil operators had acted more quickly to close valves, they would have reduced spillage by two-thirds.