CALGARY -- The CEO of Enbridge Inc. says the company's Line 3 and Line 5 pipelines in the United States are "absolutely critical" as each faces ongoing hurdles thrown up by environmental, political and other opponents.

During the Calgary-based energy infrastructure company's annual general meeting on Wednesday, Al Monaco said Enbridge must continue to fight for those pipelines for its benefit as well as the benefit of the shippers who move products on them and the consumers who need those products.

Enbridge's Line 5 is facing a looming May 12 shutdown ordered by Michigan Gov. Gretchen Whitmer last fall after accusing the company of violating terms of a 1953 deal that allowed the line to traverse the bottom of the Straits of Mackinac, which connects Lake Michigan and Lake Huron.

The 68-year-old conduit has never leaked and Enbridge has said it will ignore the order because the state doesn't have the authority to shut down the pipeline.

Meanwhile, the $9.3-billion Line 3 pipeline replacement project is under construction with a completion target of late this year, despite ongoing protests and court challenges.

In response to an investor's question of how much Enbridge spends to defend itself from legal challenges, Monaco said "a lot," but added that such costs are part of the business now.

"The infrastructure assets we own as a company and the ones we're developing and replacing, like this, and modernizing, I think are absolutely critical to the energy future no matter what the degree of change in the energy landscape is," he said.

"But I have to say, this is really part of the business today. We expect to have legal challenges and, frankly, it's the management team's job to manage those."

This report by The Canadian Press was first published May 5, 2021.