U.S. pipeline agency to probe Enbridge oil spill in Wisconsin

WASHINGTON (Reuters) - The U.S. pipeline safety agency said on Saturday it is investigating an oil spill in Wisconsin on Enbridge Inc's network that forced the Canadian company to shut down part of the main pipeline system delivering Canadian crude to U.S. refiners.

The U.S. Transportation Department's Pipeline and Hazardous Materials Safety Administration "is investigating the cause of the Enbridge crude oil pipeline failure in Wisconsin," spokesman Damon Hill said in an email, adding that an inspector "has been dispatched to the failure location."

The spill reported on Friday comes almost two years to the day after a major spill in Michigan on a different part of Enbridge's network.

On Friday, Enbridge shut down Line 14 after a leak that it estimated at around 1,200 barrels of oil. The 318,000 barrel per day (bpd) line, part of the Lakehead system, carries light crude oil to Chicago-area refineries.

The cause of Friday's spill was undetermined and Enbridge Energy Partners said it had no estimate on when flows would resume. Line 14 is one of four lines that ship mainly Canadian crude via Lakehead, a 2.5 million bpd network that is the principle route for Canadian exports.

The news will not help Enbridge build public trust in its network, which has come under scrutiny following several high-profile incidents, including a spill in Alberta last month and the massive leak in Michigan two years ago.

Just weeks ago, the U.S. National Transportation Safety Board delivered a scathing report of Enbridge's handling of the July 2010 rupture of its Line 6B near Marshall, Michigan, which led to more than 20,000 barrels of crude leaking into the Kalamazoo River.

U.S. pipeline regulators fined it $3.7 million for the spill, their largest ever penalty.

The incidents have caused furor just as the company seeks approval for its C$6 billion Northern Gateway pipeline to Canada's West Coast from Alberta amid staunch opposition from environmental groups and native communities that warn against oil spills on land and in coastal waters.

(Reporting by Timothy Gardner in Washington and Jeffrey Jones in Calgary; Editing by Vicki Allen)