TRAVERSE CITY (AP) — Michigan officials demanded an extensive set of records Monday from Enbridge Inc. in an investigation of the company’s oil pipeline that runs beneath a channel linking two of the Great Lakes.

In a letter to the Canadian company, the state Department of Natural Resources requested documents dating back to 1953, when two 20-inch pipelines were placed across the bottom of the Straits of Mackinac.

They are part of Line 5, which carries crude oil and natural gas liquids used in propane from Superior, Wisconsin, to Sarnia, Ontario. The straits connect Lakes Huron and Michigan.

Gov. Gretchen Whitmer last June ordered a review of Enbridge’s compliance with an easement that set conditions for the company to place the pipelines on the Great Lakes bottomlands.

The Democratic governor, who has echoed environmentalists’ concerns that the pipes are unsafe and could leak, said violations of the easement could justify an order to shut down the line.

“The documents requested today from Enbridge will provide important information in the department’s continuing review” of the company’s performance, said Ed Golder, spokesman for the natural resources department.

The Canadian company, based in Calgary, Alberta, issued a statement saying it had received the information request. Spokesman Michael Barnes said the company had no comment on how it would respond.

The underwater pipeline segment “has been operating safely and reliably since it was constructed more than 60 years ago,” Enbridge said.

In the letter, natural resources director Daniel Eichinger asked Enbridge to provide all company letters, emails, reports and other materials involving any spills or leaks from Line 5.