Environmentalists are concerned that TransCanada could be granted the waiver without having to alter the thickness or strength of the steel used to construct the 36-inch diameter pipeline. They say that would be a mistake, because two of the Canadian company's other pipelines lauded as "world class" don’t have stellar safety records.

The U.S. segment of the first phase of the Keystone project has already leaked 14 times since it began pumping diluted bitumen in June 2010. Twelve of those spills were large enough to be reported to federal authorities, while two of them were reported to state officials. Also, a July explosion destroyed a 40-foot section of TransCanada's Bison natural gas pipeline near Gillette, Wyo. That pipeline opened in January.

Those incidents are red flags, Swift said, when the same company is planning to route the Keystone XL under numerous rivers and a resource as bountiful as the Ogallala Aquifer. It provides drinking and irrigation water for millions of Great Plains' residents.

"A lot of arguments being put out there are preventing policy makers from seeing risks that this pipeline presents," Swift said. "We simply can't afford to be playing this game when considering a pipeline through our richest water source."