LANSING, Mich. -- Michigan's attorney general is suing to shut down dual oil pipelines in the Great Lakes.

Democrat Dana Nessel filed suit Thursday. It was the same day she also sought to dismiss pipeline operator Enbridge's request for a ruling on the legality of a deal it struck last year with former Republican Gov. Rick Snyder to put replacement pipes in a tunnel beneath the Straits of Mackinac.

Nessel says the Line 5 pipes pose an "unacceptable risk" to the Great Lakes and she moved after it became clear talks between Enbridge and Democratic Gov. Gretchen Whitmer stalled.

The pipelines are part of Enbridge's Line 5, which carries 23 million gallons (87 million litres) of crude oil and natural gas liquids daily between Superior, Wisconsin, and Sarnia, Ontario.