GRAND MARSH, Wis. (Reuters) — Enbridge of Canada expects on Monday to begin replacing part of a pipeline that leaked more than 1,000 barrels of oil in a Wisconsin field, shutting down a crucial conduit from Canada.

The spill on Friday was the latest in a series of episodes that threaten to damage the reputation of Enbridge, a company that began its most ambitious expansion program ever just two months ago. It came almost two years to the day after a ruptured Enbridge line fouled part of the Kalamazoo River in Michigan.

Enbridge said on Sunday that it tentatively planned to install a new section of pipe on Monday, although it was still unable to say when its Line 14, which moves 318,000 barrels a day, would resume service or what had caused the spill, which blackened a small field but did not appear to cause major damage.

“The line has been uncovered to begin removing the failed section and send it to a metallurgical lab for examination,” said Damon Hill, a spokesman for the federal Pipeline and Hazardous Materials Safety Administration. An agency official said that all of the pooled oil had been cleaned up.

The line transports mainly light crude oil to Chicago-area refineries.

Although the spill appeared to be relatively small and quickly contained, it comes at an uneasy time for Enbridge, which experienced another leak in Alberta a month ago and endured a scathing report from United States safety regulators over its handling of the Michigan case in 2010.

“Enbridge is fast becoming to the Midwest what BP was to the Gulf of Mexico, posing troubling risks to the environment,” Representative Ed Markey of Massachusetts, the top Democrat on the Natural Resources Committee, said in a statement.

Canada is the largest source of foreign crude oil for the United States, supplying over 2.4 million barrels a day of the more than 8.3 million barrels imported by the nation on average in July. Enbridge’s lines, the world’s largest crude oil pipeline system, carry most of those shipments.

Just two months ago, Enbridge announced a multibillion-dollar series of projects aimed at moving western Canada and North Dakota oil to Eastern refineries and eliminating costly bottlenecks in the Midwest.

Line 14 is a 24-inch diameter pipe that was installed in 1998, making it a relatively new line. Enbridge said it had been inspected twice in the last five years.