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People in Michigan are naturally concerned about the thousands of miles of pipelines crisscrossing the state. After all, Michigan suffered through the worst inland oil spill in U.S. history. 

And there's one pipeline in particular that people are quite concerned about: Enbridge's Line 5 moves more than 500,000 barrels of oil and other liquid petroleum products (like propane) a day under Lake Michigan at the Straits of Mackinac.

As one expert told me, this is "beyond a sensitive area" to oil spills.

The company, of course, tells us the pipeline is safe, but when I tried to get that independently verified last fall, I quickly discovered the company holds on tight to information about the condition of Line 5 under the Straits.

This week, the state of Michigan released a much-anticipated report from its pipeline task force, but information about the condition of Line 5 was not in it.

Here's the basic question people want answered:

What is the status of the pipeline Enbridge owns that runs under the Straits of Mackinac?

If you go to the people who you think might have the answer to that question — the state, the federal government — they all basically say the same thing, "go back to the company and ask them."

Enbridge tells everyone that the 62-year-old pipeline is safe. And they could be right. The experts I spoke with said that as long as the pipeline has been maintained well, the steel could still be in good shape.

But, of course, verification from the company is not the same as independent verification.

In order to know whether the company is right, we need to see specific test results.

Pipeline safety threats

The liquid petroleum pipelines running over land are different from the pipelines running under Lake Michigan. When Enbridge's Line 5 pipeline crosses from land into water, it splits into two pipelines.

The pipelines are smaller in diameter, they are made of thicker steel and they don't have the horizontal seams that a lot of other pipelines have that can lead to cracking.

The pipelines are smaller in diameter, they are made of thicker steel and they don't have the horizontal seams that a lot of other pipelines have that can lead to cracking.

They were built well, but that doesn't mean the underwater pipelines don't face threats.

The specific threat the pipelines under the Straits face is corrosion: corrosion from both inside and outside the pipelines.

What is the condition of the steel?

Pipeline safety expert Richard Kuprewicz, president of Accufacts Inc., says people need to ask for specific information from a tool, or a set of tools, the company uses.

"They should be able to answer your question," he says. "You know, 'How are you dealing with potential corrosion threats under the Straits?' And they'll tell you they're probably running a high resolution magnetic flux corrosion tool. And they should be able to tell you what that tool is, who makes it, and what are they finding."

These tools are known in the industry as "smart pigs."

Kuprewicz says the smart pigs used to find corrosion are pretty accurate.

We know Enbridge uses these tools, but, so far, they're not willing to share specific information about what the tools are finding.

I asked the company for that information about corrosion in Line 5. They didn't give it to me.

I sent a Freedom of Information Act request to Pipeline and Hazardous Materials Safety Administration, the federal agency that oversees pipeline safety, and they basically told me they don't have that data (see image right).

State did see some raw data

The state was given access to some data from the corrosion tool. 

Enbridge shared it with them last year after state officials sent them a list of questions about the Line 5 pipelines.

But officials told me they had to log into a website to look at that data, and when I asked if they could share it with me, I was told that Enbridge prevented them from doing so.

So I asked if they had examined the data.

They said they had not gone through the data at that time.

Nine months later

Fast forward to today, and the release of the Michigan Petroleum Pipeline Task Force Report, and the true status of the pipelines is still unknown.

After the release of the report this week, I asked again whether the state had interpreted the inline corrosion tool data.

Dan Wyant, the director of the Michigan Department of Environmental Quality, said they hadn't yet.

"Yeah, as I understand the question, you're asking did we evaluate the pipe that exists and have the technical ability to suggest the long-term viability of the pipe. And we want to do more on that," Wyant said.

Wyant said they need experts to help them do that.

Getting the experts to help them do that is part of the 13 recommendations from the pipeline task force.

The task force is also asking for more information from Enbridge in order to come to a real understanding of the health of the pipelines.

From the report:

While Enbridge has publicly listed the numbers and types of pipeline inspections that it or its contractors have performed, it has not fully disclosed the actual results of most of the inspections or the limitations of the test methods used. By not providing the State with actual copies of test results and other State-requested documents, based upon assertions of confidentiality, Enbridge has limited opportunities for independent expert review.

In a footnote, the state's pipeline task force calls into question Enbridge's claim of confidentiality:

The Task Force recognizes, of course, that public access to certain documents recognized as Critical Energy Infrastructure Information under federal law is legitimately restricted in order to protect infrastructure from sabotage or other security threats. But the Task Force disagrees that disclosing the content of test results on pipelines whose location and design have already been publicly disclosed by Enbridge itself would somehow compromise the security of the pipelines.

So, we're not any closer to understanding the true condition of these pipelines under the Straits of Mackinac.

The company still holds all the cards and we haven't seen the information to verify what they tell us yet.