Enbridge Energy Partners, a U.S. division of the Canadian pipeline company, reported a leak from its Line 14 in Grand Marsh near central Wisconsin. Richard Adams, vice president of U.S. operations for Enbridge, said in a statement the oil was contained but the response was "a top priority" for the company.
Patricia Klinger, a spokeswoman for the Pipeline and Hazardous Materials Safety Administration, said two inspectors were on site along with members of the Environmental Protection Agency, reports Bloomberg News.
Line 14 has a capacity of 317,600 barrels of oil per day. Installed in 1998, it's part of the Lakehead oil pipeline system carrying so-called tar sands oil from Canada.
The rupture of Line 14 came two years and one day after Line 6B of the Lakehead system released around 20,000 barrels of Alberta crude into southern Michigan waterways.
The National Safety Transportation Boards said Enbridge knew there were problems on Line 6B five years before the Michigan release. Bloomberg reports the failed section of the 24-inch Line 14 is on its way to a metallurgical laboratory to assess what caused the release.
Enbridge said it wasn't able to provide an estimate on when Line 14 would return to service. The Lakehead system supplies regional refineries with about 70 percent of their crude oil.