A United States State Department study released late Friday afternoon found “no significant impacts to most resources” along the route of a proposed pipeline extension from Canada to Oklahoma, defying environmentalists’ warnings that building the pipeline will degrade underwater water supplies.

The report leaves President Barack Obama, who delayed approval of the pipeline’s construction more than a year ago, with little reason to further obstruct the project.

A previous State Department study, released in August 2011, similarly anticipated minimal environmental impact from building the pipeline.

The $7 billion Keystone XL Pipeline is supposed to carry the equivalent of more than 700,000 barrels of oil per day from the tar fields of Alberta to refineries and ports along the Gulf of Mexico.

Labor unions favor approval of building the pipeline because it will create American construction jobs. Environmentalists, another key constituency for the Democratic president, argue that it would further increase Canadian oil sand production which is more polluting than conventional oil extraction.

Without addressing such emissions overtly, the State Department recognizes in its latest report that Canada will tap into its lucrative oil sands “with or without the proposed project.” It adds that “approval or denial of the proposed project is unlikely to have a substantial impact on the rate of development in the oil sands or on the amount of heavy crude oil refined in the Gulf Coast area.”

Alberta’s daily oil production of 1.5 million barrels of oil is expected to more than double in the next fifteen years. If the Keystone XL Pipeline isn’t build, Canada will likely export more oil to countries like China independently.

Opposition Republicans, who favor the pipeline’s construction, were quick to chastise the president for postponing approval for so long. “Today’s report again makes clear there is no reason for this critical pipeline to be blocked one more day,” said John Boehner, the Republican leader in the House of Representatives, in a statement.

After four years of needless delays, it is time for President Obama to stand up for middle-class jobs and energy security and approve the Keystone Pipeline.