The U.S. State Department's new report on the Keystone XL oil pipeline is making the project's opponents uneasy, by acknowledging that whether or not the pipeline is built, heavy crude will still be extracted from Canada's oil sands. It also points out that refineries on the Gulf Coast will keep refining heavy crude from somewhere -- some of it shipped from Canada and some from Venezuela and Mexico.

That's not exactly surprising. There was little reason to expect that, in drafting a second environmental impact report on the pipeline, the State Department would suddenly come up with reasons to deny a permit that weren't in the report that came out a year and a half ago.

The pipeline is still not the environmental disaster that some of its opponents have portrayed it to be. As Bloomberg View has noted more than once, it would do little to increase greenhouse-gas emissions in North America.

One thing that is different about this report is a new focus on oil from the Bakken region in North Dakota and Montana. Originally, the pipeline was to carry just 700,000 barrels a day of heavy crude from the oil sands in Alberta, Canada. Now, its capacity is said to be 830,000 barrels a day, 100,000 of which are set aside for light Bakken crude.

That is, American oil.

Bakken production is now over 500,000 barrels a day and rising, and most of this is being sent to refineries by truck and rail. By handling some of it, Keystone would be knit into the U.S. domestic oil-supply network, making it even more important to the U.S. economy and energy security.

As the State Department report notes, U.S. refiners see "economic advantages" to processing Canadian and North Dakotan crude, "which are both growing in supply and may be less expensive to transport to the refinery than imported crude oils that are shipped by tanker."

It bears repeating that Obama has never expressed any real opposition to Keystone -- only to its original route though the Nebraska Sand Hills. Once there's been time for public comment on today's environmental impact report, Obama should allow TransCanada to go ahead and build the pipeline.

(Mary Duenwald is a member of the Bloomberg View editorial board.)