The significance of the U.S. Environmental Protection Agency's critique of the State Dept.'s draft supplemental environmental impact statement for the Keystone XL pipeline is, apparently, in the eye of the beholder.

Proponents of TransCanada's $5.3-billion project say EPA's April 22 letter to the State Dept. is nothing more than a call for tweaking the environmental document to address some lingering issues. However, opponents say EPA's comments pose important questions.

Sabrina Fang, an American Petroleum Institute spokeswoman, says the project "is safe and will create tens of thousands of well-paying jobs. Nothing in the EPA letter undermines the validity of that conclusion." But Rachel Wolf—a spokeswoman for the All Risk, No Reward Coalition, which comprises anti-Keystone environmental groups—says it notes "very serious concerns" about the pipeline's climate-change impact, potential for spills and route through an important aquifer.

EPA Assistant Administrator Cynthia Giles said in the letter that although the review concludes Alberta's oil sands will be developed whether or not the pipeline is built, the final State Dept. EIS should "provide a more careful review of the market analysis and rail transport options" to determine whether that analysis is accurate.

TransCanada is anxious to see the project move forward. Alexander Pourbaix, the company's president of energy and oil pipelines, told energy analysts on April 26 that TransCanada needs U.S. approval by July 1—or soon after that—for the pipeline to begin commercial operation in the second half of 2015.

A decision by midyear is highly unlikely, says Anthony Swift, an attorney with the Natural Resources Defense Council's international program. Given the environmental review timeline, he says, "it would be almost impossible to have a decision before the fall."

Swift notes that EPA gave the State Dept. draft a rating of EO-2, for "environmental objections/insufficient information." EPA gives fewer than one in 20 EIS reports ratings that low, he says.