The National Resources Defense Council says the U.S. State Department is not looking closely enough at the environmental impacts of TransCanada's proposed Keystone XL pipeline project.

A U.S. State Department report says the pipeline poses no major risk, saying there is no evidence the pipeline would significantly affect the six U.S. states it would pass through.

But opponents say it's an environmental disaster waiting to happen — and they point to several recent pipeline spills as proof.

Susan Casey-Lefkowitz with the National Resource Defense Council said the study is missing some critical elements, including an in-depth review of pipeline safety issues, added pollution in refinery communities and a special assessment of the impact on wildlife.

"Once again, the State Department has failed to do its homework, and they’re leaving the American public to suffer the consequences," she said.

“It is utterly beyond me how the administration can claim the pipeline will have 'no significant impacts' if they haven’t bothered to do in-depth studies around the issues of contention. The public has made their concerns clear and the administration seems to have ignored them. If permitted, the proposed Keystone XL tar sands pipeline will be a dirty legacy that will haunt [the Obama administration] for years to come."

Casey-Lefkowitz said there is no evidence of the in-depth studies required for such a project.

"Despite assurances, this review seems to be far from a 'thorough and objective' assessment of critical health and safety issues that landowners and community members will be dealing with should this project be built," she said.

"An administration committed to fighting climate change and building a clean energy economy in the United States must be more stringent in evaluating the vast impacts of this dirty and unnecessary project."

She urged the U.S. government to proceed with public meeting and further assessments before determining whether to proceed.

"Keystone XL is rife with issues that exacerbate climate change and environmental injustices — two things that were supposed to be a focus for the administration, but have been glossed over," Casey-Lefkowitz said. "Especially given that there is no need for this pipeline in the United States, it is not worth the many environmental and safety risks."

With the approval completed, the U.S. government now has 90 days to decide if the project, which would stretch from Alberta to the U.S. Gulf Coast, is in the public interest.

The project still needs the approval of U.S. President Obama, who has promised to make a decision by the end of the year.

Calgary-based energy giant TransCanada says it iready to begin construction early next year if Obama gives the green light.

With files from The Canadian Press