A single leaking tank car on a Canadian Pacific oil train left a sheen of crude oil Monday along 70 miles of track between Red Wing and Winona, Minn., state and railroad officials said.

An estimated 12,000 gallons of oil, or less than half the tank car’s contents, leaked out before the malfunctioning valve was discovered by rail workers late Monday morning north of Winona, said Cathy Rofshus, spokeswoman for the Minnesota Pollution Control Agency in Rochester.

On two railroad bridges, the leaking oil dripped through the ties into the Cannon and Zumbro rivers and left a light sheen, Rofshus said.

Much of the leaking oil landed on ballast rock, she said. The tracks run parallel to the Mississippi River, which was not affected.

“It looks like it is pretty much contained to the railroad bed,” she said. “It seems like it didn’t penetrate very far down. We are not going at this point to require removal of 70 miles of rock.”

One concern is that as snow melts, traces of oil might flow into waterways, Rofshus said. Canadian Pacific will need to monitor that risk and address potential problems, she added.

Ed Greenberg said Canadian Pacific’s environmental experts will work with state investigators and determine whether environmental remediation is needed.

Railroads now carry more than 10 percent of U.S. crude oil, with much of it loaded in North Dakota, which lacks sufficient pipelines to transport oil to distant refineries. Canadian Pacific, whose U.S. headquarters is in Minneapolis, and BNSF Railway Co. regularly transport crude oil through Minnesota.

Recent oil-train accidents, including a July 2013 crash that killed 47 people in Quebec and a Dec. 30 accident that triggered a partial evacuation of Casselton, N.D., have led to calls by safety experts and public officials to improve rail safety.


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