Enbridge said Tuesday it would defy Michigan's demand to shut down an oil pipeline that runs through a channel linking two of the Great Lakes.

The Calgary-based company shut down both legs of the pipeline in June after noticing a disturbance to an underwater anchor supporting the eastern line.

Oilsands companies are restoring thousands of barrels of daily production to take advantage of higher oil prices as relaxed pandemic measures allow North American consumers to get back on the road.

The U.S. Army Corps of Engineers says it's preparing to decide whether to let Alberta-based Enbridge install supports for its underwater oil pipeline in Michigan's Straits of Mackinac.

The Calgary-based company said the opening between the pipe and the bottom of the Straits of Mackinac poses "no safety or integrity risk,'' an assessment that state regulators said they couldn't immediately confirm.

 A Native American tribe in Wisconsin is suing Enbridge Inc in a bid to shut down an aging oil pipeline that runs across its tribal land, the latest in a string of challenges against the Canadian company's pipelines in the U.S. Midwest.

Enbridge insists the Line 5 dual pipes, which have been in place since 1953, are in sound condition and could operate indefinitely.

Michigan Gov. Rick Snyder said Monday he had "significant'' concerns after Enbridge, the company that operates twin oil pipelines in a Great Lakes waterway, told state officials it had found additional gaps in pipeline coating.

Hundreds of kilometres of Lake Michigan and Lake Huron shoreline are at risk of contamination if an Enbridge pipeline that runs between them ruptures, according to a study released Thursday.