I have been struck by the number of ads lately in the Star Tribune in elsewhere that promote both the unique relationship between the U.S. and its neighbor to the north, and our use of the oil that comes from Canada.
It's all part of dueling campaigns underway about the promise and perils of dirty oil.

This week it was all ramped up a notch by a little oil spill in North Dakota.

An open pit mine for oil sands near Fort McMurray in Alberta, Canada.


From a 2007 event: Enbridge workers vacuum up crude oil Thursday near Clearbrook, Minn. at the site where a pipeline caught fire a day earlier killing two Enbridge employees.


TransCanada Corp., the pipeline company that moves oil across the United States, said on Monday that its Keystone
pipeline system spilled about 500 barrels of oil at a pump station 40 miles southwest of Milnor, N.D. The timing for
TransCanada isn't great -- it's getting heightened scrutiny from Washington over plans to expand the pipeline.

According to the Wall Street Journal, the spill occurred early Saturday morning, resulting from a valve failure at a pump station. It was contained on TransCanada's property, and most of it has been cleaned up, company spokesman Terry Cunha said on Monday.

The pipeline currently carries up to 591,000 barrels a day of heavy oil from oil-sands developments in northern Alberta, in Canada's west, to Cushing, Okla., a key U.S. oil-storage crossroads, and refineries in Illinois. TransCanada is seeking approval from the U.S. State Department to expand the Keystone system to 1.1 million barrels a day and to extend it from Cushing to refineries on the U.S. Gulf coast. A decision is expected this year.

And this is where the dueling campaigns come into play. Environmentalists are fighting the expansion plans,and are
using the possibility of oil spills along the line as a primary strategy to galvanize public concern. TransCanada said the spill was caused by the latest in a series of pump-station equipment failures, according to the WSJ. That's true of all 10 spills along the Keystone system that have occurred since it opened last June. All the spills were contained on TransCanada property.Saturday's spill of 500 barrels was the largest so far.

Minnesota is especially vulnerable. The Canadian company Enbridge Inc. completed two new pipelines in 2010. One,
known as the Alberta Clipper, carries tar sands oil to Superior, Wis., where it links with another pipeline and refineries in Chicago. The second runs parallel to it, but carries a highly toxic petroleum product back to Alberta, where it is used as a thinner for the viscous crude.

Canadian oil sands are already a primary source of gasoline and other fuels for Minnesota, and are expected to
become America's top source of imported oil this year, roughly equaling the combined imports from Saudi Arabia and
Kuwait.