Canada’s Enbridge Inc. was assailed on Capitol Hill on yesterday for America’s lesser-known oil spill, one that spewed almost a million gallons of crude into a rural Michigan river this summer and proved a “stab in the heart” for the surrounding community.

“This spill went undetected, or unresponded to, for a very long period of time,” James Oberstar, chairman of the House of Representatives’ transportation and infrastructure committee, told Enbridge CEO Patrick Daniel. “Why did it take so long to shut off that pipeline?”

Daniel didn’t directly answer the question, failing to explain why it took several hours in the early morning hours of July 26 to permanently shut off the pipeline despite a series of alarms going off in the company’s Edmonton command centre.